drivers/net/sunqe.h


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/* $Id: sunqe.h,v 1.13 2000/02/09 11:15:42 davem Exp $
 * sunqe.h: Definitions for the Sun QuadEthernet driver.
 *
 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
 */

#ifndef _SUNQE_H
#define _SUNQE_H

/* QEC global registers. */
#define GLOB_CTRL	0x00UL		/* Control			*/
#define GLOB_STAT	0x04UL		/* Status			*/
#define GLOB_PSIZE	0x08UL		/* Packet Size			*/
#define GLOB_MSIZE	0x0cUL		/* Local-memory Size		*/
#define GLOB_RSIZE	0x10UL		/* Receive partition size	*/
#define GLOB_TSIZE	0x14UL		/* Transmit partition size	*/
#define GLOB_REG_SIZE	0x18UL

#define GLOB_CTRL_MMODE       0x40000000 /* MACE qec mode            */
#define GLOB_CTRL_BMODE       0x10000000 /* BigMAC qec mode          */
#define GLOB_CTRL_EPAR        0x00000020 /* Enable parity            */
#define GLOB_CTRL_ACNTRL      0x00000018 /* SBUS arbitration control */
#define GLOB_CTRL_B64         0x00000004 /* 64 byte dvma bursts      */
#define GLOB_CTRL_B32         0x00000002 /* 32 byte dvma bursts      */
#define GLOB_CTRL_B16         0x00000000 /* 16 byte dvma bursts      */
#define GLOB_CTRL_RESET       0x00000001 /* Reset the QEC            */

#define GLOB_STAT_TX          0x00000008 /* BigMAC Transmit IRQ      */
#define GLOB_STAT_RX          0x00000004 /* BigMAC Receive IRQ       */
#define GLOB_STAT_BM          0x00000002 /* BigMAC Global IRQ        */
#define GLOB_STAT_ER          0x00000001 /* BigMAC Error IRQ         */

#define GLOB_PSIZE_2048       0x00       /* 2k packet size           */
#define GLOB_PSIZE_4096       0x01       /* 4k packet size           */
#define GLOB_PSIZE_6144       0x10       /* 6k packet size           */
#define GLOB_PSIZE_8192       0x11       /* 8k packet size           */

/* In MACE mode, there are four qe channels.  Each channel has it's own
 * status bits in the QEC status register.  This macro picks out the
 * ones you want.
 */
#define GLOB_STAT_PER_QE(status, channel) (((status) >> ((channel) * 4)) & 0xf)

/* The following registers are for per-qe channel information/status. */
#define CREG_CTRL	0x00UL	/* Control                   */
#define CREG_STAT	0x04UL	/* Status                    */
#define CREG_RXDS	0x08UL	/* RX descriptor ring ptr    */
#define CREG_TXDS	0x0cUL	/* TX descriptor ring ptr    */
#define CREG_RIMASK	0x10UL	/* RX Interrupt Mask         */
#define CREG_TIMASK	0x14UL	/* TX Interrupt Mask         */
#define CREG_QMASK	0x18UL	/* QEC Error Interrupt Mask  */
#define CREG_MMASK	0x1cUL	/* MACE Error Interrupt Mask */
#define CREG_RXWBUFPTR	0x20UL	/* Local memory rx write ptr */
#define CREG_RXRBUFPTR	0x24UL	/* Local memory rx read ptr  */
#define CREG_TXWBUFPTR	0x28UL	/* Local memory tx write ptr */
#define CREG_TXRBUFPTR	0x2cUL	/* Local memory tx read ptr  */
#define CREG_CCNT	0x30UL	/* Collision Counter         */
#define CREG_PIPG	0x34UL	/* Inter-Frame Gap           */
#define CREG_REG_SIZE	0x38UL

#define CREG_CTRL_RXOFF       0x00000004  /* Disable this qe's receiver*/
#define CREG_CTRL_RESET       0x00000002  /* Reset this qe channel     */
#define CREG_CTRL_TWAKEUP     0x00000001  /* Transmitter Wakeup, 'go'. */

#define CREG_STAT_EDEFER      0x10000000  /* Excessive Defers          */
#define CREG_STAT_CLOSS       0x08000000  /* Carrier Loss              */
#define CREG_STAT_ERETRIES    0x04000000  /* More than 16 retries      */
#define CREG_STAT_LCOLL       0x02000000  /* Late TX Collision         */
#define CREG_STAT_FUFLOW      0x01000000  /* FIFO Underflow            */
#define CREG_STAT_JERROR      0x00800000  /* Jabber Error              */
#define CREG_STAT_BERROR      0x00400000  /* Babble Error              */
#define CREG_STAT_TXIRQ       0x00200000  /* Transmit Interrupt        */
#define CREG_STAT_CCOFLOW     0x00100000  /* TX Coll-counter Overflow  */
#define CREG_STAT_TXDERROR    0x00080000  /* TX Descriptor is bogus    */
#define CREG_STAT_TXLERR      0x00040000  /* Late Transmit Error       */
#define CREG_STAT_TXPERR      0x00020000  /* Transmit Parity Error     */
#define CREG_STAT_TXSERR      0x00010000  /* Transmit SBUS error ack   */
#define CREG_STAT_RCCOFLOW    0x00001000  /* RX Coll-counter Overflow  */
#define CREG_STAT_RUOFLOW     0x00000800  /* Runt Counter Overflow     */
#define CREG_STAT_MCOFLOW     0x00000400  /* Missed Counter Overflow   */
#define CREG_STAT_RXFOFLOW    0x00000200  /* RX FIFO Overflow          */
#define CREG_STAT_RLCOLL      0x00000100  /* RX Late Collision         */
#define CREG_STAT_FCOFLOW     0x00000080  /* Frame Counter Overflow    */
#define CREG_STAT_CECOFLOW    0x00000040  /* CRC Error-counter Overflow*/
#define CREG_STAT_RXIRQ       0x00000020  /* Receive Interrupt         */
#define CREG_STAT_RXDROP      0x00000010  /* Dropped a RX'd packet     */
#define CREG_STAT_RXSMALL     0x00000008  /* Receive buffer too small  */
#define CREG_STAT_RXLERR      0x00000004  /* Receive Late Error        */
#define CREG_STAT_RXPERR      0x00000002  /* Receive Parity Error      */
#define CREG_STAT_RXSERR      0x00000001  /* Receive SBUS Error ACK    */

#define CREG_STAT_ERRORS      (CREG_STAT_EDEFER|CREG_STAT_CLOSS|CREG_STAT_ERETRIES|     \
			       CREG_STAT_LCOLL|CREG_STAT_FUFLOW|CREG_STAT_JERROR|       \
			       CREG_STAT_BERROR|CREG_STAT_CCOFLOW|CREG_STAT_TXDERROR|   \
			       CREG_STAT_TXLERR|CREG_STAT_TXPERR|CREG_STAT_TXSERR|      \
			       CREG_STAT_RCCOFLOW|CREG_STAT_RUOFLOW|CREG_STAT_MCOFLOW| \
			       CREG_STAT_RXFOFLOW|CREG_STAT_RLCOLL|CREG_STAT_FCOFLOW|   \
			       CREG_STAT_CECOFLOW|CREG_STAT_RXDROP|CREG_STAT_RXSMALL|   \
			       CREG_STAT_RXLERR|CREG_STAT_RXPERR|CREG_STAT_RXSERR)

#define CREG_QMASK_COFLOW     0x00100000  /* CollCntr overflow         */
#define CREG_QMASK_TXDERROR   0x00080000  /* TXD error                 */
#define CREG_QMASK_TXLERR     0x00040000  /* TX late error             */
#define CREG_QMASK_TXPERR     0x00020000  /* TX parity error           */
#define CREG_QMASK_TXSERR     0x00010000  /* TX sbus error ack         */
#define CREG_QMASK_RXDROP     0x00000010  /* RX drop                   */
#define CREG_QMASK_RXBERROR   0x00000008  /* RX buffer error           */
#define CREG_QMASK_RXLEERR    0x00000004  /* RX late error             */
#define CREG_QMASK_RXPERR     0x00000002  /* RX parity error           */
#define CREG_QMASK_RXSERR     0x00000001  /* RX sbus error ack         */

#define CREG_MMASK_EDEFER     0x10000000  /* Excess defer              */
#define CREG_MMASK_CLOSS      0x08000000  /* Carrier loss              */
#define CREG_MMASK_ERETRY     0x04000000  /* Excess retry              */
#define CREG_MMASK_LCOLL      0x02000000  /* Late collision error      */
#define CREG_MMASK_UFLOW      0x01000000  /* Underflow                 */
#define CREG_MMASK_JABBER     0x00800000  /* Jabber error              */
#define CREG_MMASK_BABBLE     0x00400000  /* Babble error              */
#define CREG_MMASK_OFLOW      0x00000800  /* Overflow                  */
#define CREG_MMASK_RXCOLL     0x00000400  /* RX Coll-Cntr overflow     */
#define CREG_MMASK_RPKT       0x00000200  /* Runt pkt overflow         */
#define CREG_MMASK_MPKT       0x00000100  /* Missed pkt overflow       */

#define CREG_PIPG_TENAB       0x00000020  /* Enable Throttle           */
#define CREG_PIPG_MMODE       0x00000010  /* Manual Mode               */
#define CREG_PIPG_WMASK       0x0000000f  /* SBUS Wait Mask            */

/* Per-channel AMD 79C940 MACE registers. */
#define MREGS_RXFIFO	0x00UL	/* Receive FIFO                   */
#define MREGS_TXFIFO	0x01UL	/* Transmit FIFO                  */
#define MREGS_TXFCNTL	0x02UL	/* Transmit Frame Control         */
#define MREGS_TXFSTAT	0x03UL	/* Transmit Frame Status          */
#define MREGS_TXRCNT	0x04UL	/* Transmit Retry Count           */
#define MREGS_RXFCNTL	0x05UL	/* Receive Frame Control          */
#define MREGS_RXFSTAT	0x06UL	/* Receive Frame Status           */
#define MREGS_FFCNT	0x07UL	/* FIFO Frame Count               */
#define MREGS_IREG	0x08UL	/* Interrupt Register             */
#define MREGS_IMASK	0x09UL	/* Interrupt Mask                 */
#define MREGS_POLL	0x0aUL	/* POLL Register                  */
#define MREGS_BCONFIG	0x0bUL	/* BIU Config                     */
#define MREGS_FCONFIG	0x0cUL	/* FIFO Config                    */
#define MREGS_MCONFIG	0x0dUL	/* MAC Config                     */
#define MREGS_PLSCONFIG	0x0eUL	/* PLS Config                     */
#define MREGS_PHYCONFIG	0x0fUL	/* PHY Config                     */
#define MREGS_CHIPID1	0x10UL	/* Chip-ID, low bits              */
#define MREGS_CHIPID2	0x11UL	/* Chip-ID, high bits             */
#define MREGS_IACONFIG	0x12UL	/* Internal Address Config        */
	/* 0x13UL, reserved */
#define MREGS_FILTER	0x14UL	/* Logical Address Filter         */
#define MREGS_ETHADDR	0x15UL	/* Our Ethernet Address           */
	/* 0x16UL, reserved */
	/* 0x17UL, reserved */
#define MREGS_MPCNT	0x18UL	/* Missed Packet Count            */
	/* 0x19UL, reserved */
#define MREGS_RPCNT	0x1aUL	/* Runt Packet Count              */
#define MREGS_RCCNT	0x1bUL	/* RX Collision Count             */
	/* 0x1cUL, reserved */
#define MREGS_UTEST	0x1dUL	/* User Test                      */
#define MREGS_RTEST1	0x1eUL	/* Reserved Test 1                */
#define MREGS_RTEST2	0x1fUL	/* Reserved Test 2                */
#define MREGS_REG_SIZE	0x20UL

#define MREGS_TXFCNTL_DRETRY        0x80 /* Retry disable                  */
#define MREGS_TXFCNTL_DFCS          0x08 /* Disable TX FCS                 */
#define MREGS_TXFCNTL_AUTOPAD       0x01 /* TX auto pad                    */

#define MREGS_TXFSTAT_VALID         0x80 /* TX valid                       */
#define MREGS_TXFSTAT_UNDERFLOW     0x40 /* TX underflow                   */
#define MREGS_TXFSTAT_LCOLL         0x20 /* TX late collision              */
#define MREGS_TXFSTAT_MRETRY        0x10 /* TX > 1 retries                 */
#define MREGS_TXFSTAT_ORETRY        0x08 /* TX 1 retry                     */
#define MREGS_TXFSTAT_PDEFER        0x04 /* TX pkt deferred                */
#define MREGS_TXFSTAT_CLOSS         0x02 /* TX carrier lost                */
#define MREGS_TXFSTAT_RERROR        0x01 /* TX retry error                 */

#define MREGS_TXRCNT_EDEFER         0x80 /* TX Excess defers               */
#define MREGS_TXRCNT_CMASK          0x0f /* TX retry count                 */

#define MREGS_RXFCNTL_LOWLAT        0x08 /* RX low latency                 */
#define MREGS_RXFCNTL_AREJECT       0x04 /* RX addr match rej              */
#define MREGS_RXFCNTL_AUTOSTRIP     0x01 /* RX auto strip                  */

#define MREGS_RXFSTAT_OVERFLOW      0x80 /* RX overflow                    */
#define MREGS_RXFSTAT_LCOLL         0x40 /* RX late collision              */
#define MREGS_RXFSTAT_FERROR        0x20 /* RX framing error               */
#define MREGS_RXFSTAT_FCSERROR      0x10 /* RX FCS error                   */
#define MREGS_RXFSTAT_RBCNT         0x0f /* RX msg byte count              */

#define MREGS_FFCNT_RX              0xf0 /* RX FIFO frame cnt              */
#define MREGS_FFCNT_TX              0x0f /* TX FIFO frame cnt              */

#define MREGS_IREG_JABBER           0x80 /* IRQ Jabber error               */
#define MREGS_IREG_BABBLE           0x40 /* IRQ Babble error               */
#define MREGS_IREG_COLL             0x20 /* IRQ Collision error            */
#define MREGS_IREG_RCCO             0x10 /* IRQ Collision cnt overflow     */
#define MREGS_IREG_RPKTCO           0x08 /* IRQ Runt packet count overflow */
#define MREGS_IREG_MPKTCO           0x04 /* IRQ missed packet cnt overflow */
#define MREGS_IREG_RXIRQ            0x02 /* IRQ RX'd a packet              */
#define MREGS_IREG_TXIRQ            0x01 /* IRQ TX'd a packet              */

#define MREGS_IMASK_BABBLE          0x40 /* IMASK Babble errors            */
#define MREGS_IMASK_COLL            0x20 /* IMASK Collision errors         */
#define MREGS_IMASK_MPKTCO          0x04 /* IMASK Missed pkt cnt overflow  */
#define MREGS_IMASK_RXIRQ           0x02 /* IMASK RX interrupts            */
#define MREGS_IMASK_TXIRQ           0x01 /* IMASK TX interrupts            */

#define MREGS_POLL_TXVALID          0x80 /* TX is valid                    */
#define MREGS_POLL_TDTR             0x40 /* TX data transfer request       */
#define MREGS_POLL_RDTR             0x20 /* RX data transfer request       */

#define MREGS_BCONFIG_BSWAP         0x40 /* Byte Swap                      */
#define MREGS_BCONFIG_4TS           0x00 /* 4byte transmit start point     */
#define MREGS_BCONFIG_16TS          0x10 /* 16byte transmit start point    */
#define MREGS_BCONFIG_64TS          0x20 /* 64byte transmit start point    */
#define MREGS_BCONFIG_112TS         0x30 /* 112byte transmit start point   */
#define MREGS_BCONFIG_RESET         0x01 /* SW-Reset the MACE              */

#define MREGS_FCONFIG_TXF8          0x00 /* TX fifo 8 write cycles         */
#define MREGS_FCONFIG_TXF32         0x80 /* TX fifo 32 write cycles        */
#define MREGS_FCONFIG_TXF16         0x40 /* TX fifo 16 write cycles        */
#define MREGS_FCONFIG_RXF64         0x20 /* RX fifo 64 write cycles        */
#define MREGS_FCONFIG_RXF32         0x10 /* RX fifo 32 write cycles        */
#define MREGS_FCONFIG_RXF16         0x00 /* RX fifo 16 write cycles        */
#define MREGS_FCONFIG_TFWU          0x08 /* TX fifo watermark update       */
#define MREGS_FCONFIG_RFWU          0x04 /* RX fifo watermark update       */
#define MREGS_FCONFIG_TBENAB        0x02 /* TX burst enable                */
#define MREGS_FCONFIG_RBENAB        0x01 /* RX burst enable                */

#define MREGS_MCONFIG_PROMISC       0x80 /* Promiscuous mode enable        */
#define MREGS_MCONFIG_TPDDISAB      0x40 /* TX 2part deferral enable       */
#define MREGS_MCONFIG_MBAENAB       0x20 /* Modified backoff enable        */
#define MREGS_MCONFIG_RPADISAB      0x08 /* RX physical addr disable       */
#define MREGS_MCONFIG_RBDISAB       0x04 /* RX broadcast disable           */
#define MREGS_MCONFIG_TXENAB        0x02 /* Enable transmitter             */
#define MREGS_MCONFIG_RXENAB        0x01 /* Enable receiver                */

#define MREGS_PLSCONFIG_TXMS        0x08 /* TX mode select                 */
#define MREGS_PLSCONFIG_GPSI        0x06 /* Use GPSI connector             */
#define MREGS_PLSCONFIG_DAI         0x04 /* Use DAI connector              */
#define MREGS_PLSCONFIG_TP          0x02 /* Use TwistedPair connector      */
#define MREGS_PLSCONFIG_AUI         0x00 /* Use AUI connector              */
#define MREGS_PLSCONFIG_IOENAB      0x01 /* PLS I/O enable                 */

#define MREGS_PHYCONFIG_LSTAT       0x80 /* Link status                    */
#define MREGS_PHYCONFIG_LTESTDIS    0x40 /* Disable link test logic        */
#define MREGS_PHYCONFIG_RXPOLARITY  0x20 /* RX polarity                    */
#define MREGS_PHYCONFIG_APCDISAB    0x10 /* AutoPolarityCorrect disab      */
#define MREGS_PHYCONFIG_LTENAB      0x08 /* Select low threshold           */
#define MREGS_PHYCONFIG_AUTO        0x04 /* Connector port auto-sel        */
#define MREGS_PHYCONFIG_RWU         0x02 /* Remote WakeUp                  */
#define MREGS_PHYCONFIG_AW          0x01 /* Auto Wakeup                    */

#define MREGS_IACONFIG_ACHNGE       0x80 /* Do address change              */
#define MREGS_IACONFIG_PARESET      0x04 /* Physical address reset         */
#define MREGS_IACONFIG_LARESET      0x02 /* Logical address reset          */

#define MREGS_UTEST_RTRENAB         0x80 /* Enable resv test register      */
#define MREGS_UTEST_RTRDISAB        0x40 /* Disab resv test register       */
#define MREGS_UTEST_RPACCEPT        0x20 /* Accept runt packets            */
#define MREGS_UTEST_FCOLL           0x10 /* Force collision status         */
#define MREGS_UTEST_FCSENAB         0x08 /* Enable FCS on RX               */
#define MREGS_UTEST_INTLOOPM        0x06 /* Intern lpback w/MENDEC         */
#define MREGS_UTEST_INTLOOP         0x04 /* Intern lpback                  */
#define MREGS_UTEST_EXTLOOP         0x02 /* Extern lpback                  */
#define MREGS_UTEST_NOLOOP          0x00 /* No loopback                    */

struct qe_rxd {
	u32 rx_flags;
	u32 rx_addr;
};

#define RXD_OWN      0x80000000 /* Ownership.      */
#define RXD_UPDATE   0x10000000 /* Being Updated?  */
#define RXD_LENGTH   0x000007ff /* Packet Length.  */

struct qe_txd {
	u32 tx_flags;
	u32 tx_addr;
};

#define TXD_OWN      0x80000000 /* Ownership.      */
#define TXD_SOP      0x40000000 /* Start Of Packet */
#define TXD_EOP      0x20000000 /* End Of Packet   */
#define TXD_UPDATE   0x10000000 /* Being Updated?  */
#define TXD_LENGTH   0x000007ff /* Packet Length.  */

#define TX_RING_MAXSIZE   256
#define RX_RING_MAXSIZE   256

#define TX_RING_SIZE      16
#define RX_RING_SIZE      16

#define NEXT_RX(num)       (((num) + 1) & (RX_RING_MAXSIZE - 1))
#define NEXT_TX(num)       (((num) + 1) & (TX_RING_MAXSIZE - 1))
#define PREV_RX(num)       (((num) - 1) & (RX_RING_MAXSIZE - 1))
#define PREV_TX(num)       (((num) - 1) & (TX_RING_MAXSIZE - 1))

#define TX_BUFFS_AVAIL(qp)                                    \
        (((qp)->tx_old <= (qp)->tx_new) ?                     \
	  (qp)->tx_old + (TX_RING_SIZE - 1) - (qp)->tx_new :  \
			    (qp)->tx_old - (qp)->tx_new - 1)

struct qe_init_block {
	struct qe_rxd qe_rxd[RX_RING_MAXSIZE];
	struct qe_txd qe_txd[TX_RING_MAXSIZE];
};

#define qib_offset(mem, elem) \
((__u32)((unsigned long)(&(((struct qe_init_block *)0)->mem[elem]))))

struct sunqe;

struct sunqec {
	void __iomem		*gregs;		/* QEC Global Registers         */
	struct sunqe		*qes[4];	/* Each child MACE              */
	unsigned int            qec_bursts;	/* Support burst sizes          */
	struct sbus_dev		*qec_sdev;	/* QEC's SBUS device            */
	struct sunqec		*next_module;	/* List of all QECs in system   */
};

#define PKT_BUF_SZ	1664
#define RXD_PKT_SZ	1664

struct sunqe_buffers {
	u8	tx_buf[TX_RING_SIZE][PKT_BUF_SZ];
	u8	__pad[2];
	u8	rx_buf[RX_RING_SIZE][PKT_BUF_SZ];
};

#define qebuf_offset(mem, elem) \
((__u32)((unsigned long)(&(((struct sunqe_buffers *)0)->mem[elem][0]))))

struct sunqe {
	void __iomem			*qcregs;		/* QEC per-channel Registers   */
	void __iomem			*mregs;		/* Per-channel MACE Registers  */
	struct qe_init_block      	*qe_block;	/* RX and TX descriptors       */
	__u32                      	qblock_dvma;	/* RX and TX descriptors       */
	spinlock_t			lock;		/* Protects txfull state       */
	int                        	rx_new, rx_old;	/* RX ring extents	       */
	int			   	tx_new, tx_old;	/* TX ring extents	       */
	struct sunqe_buffers		*buffers;	/* CPU visible address.        */
	__u32				buffers_dvma;	/* DVMA visible address.       */
	struct sunqec			*parent;
	u8				mconfig;	/* Base MACE mconfig value     */
	struct sbus_dev			*qe_sdev;	/* QE's SBUS device struct     */
	struct net_device		*dev;		/* QE's netdevice struct       */
	int				channel;	/* Who am I?                   */
};

#endif /* !(_SUNQE_H) */
/*
 *  linux/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
 *
 *  2003-06-02  Jim Houston - Concurrent Computer Corp.
 *		Changes to use preallocated sigqueue structures
 *		to allow signals to be sent reliably.
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/binfmts.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/ptrace.h>
#include <linux/signal.h>
#include <linux/capability.h>
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
#include <linux/nsproxy.h>

#include <asm/param.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/siginfo.h>
#include "audit.h"	/* audit_signal_info() */

/*
 * SLAB caches for signal bits.
 */

static struct kmem_cache *sigqueue_cachep;

/*
 * In POSIX a signal is sent either to a specific thread (Linux task)
 * or to the process as a whole (Linux thread group).  How the signal
 * is sent determines whether it's to one thread or the whole group,
 * which determines which signal mask(s) are involved in blocking it
 * from being delivered until later.  When the signal is delivered,
 * either it's caught or ignored by a user handler or it has a default
 * effect that applies to the whole thread group (POSIX process).
 *
 * The possible effects an unblocked signal set to SIG_DFL can have are:
 *   ignore	- Nothing Happens
 *   terminate	- kill the process, i.e. all threads in the group,
 * 		  similar to exit_group.  The group leader (only) reports
 *		  WIFSIGNALED status to its parent.
 *   coredump	- write a core dump file describing all threads using
 *		  the same mm and then kill all those threads
 *   stop 	- stop all the threads in the group, i.e. TASK_STOPPED state
 *
 * SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
 * Other signals when not blocked and set to SIG_DFL behaves as follows.
 * The job control signals also have other special effects.
 *
 *	+--------------------+------------------+
 *	|  POSIX signal      |  default action  |
 *	+--------------------+------------------+
 *	|  SIGHUP            |  terminate	|
 *	|  SIGINT            |	terminate	|
 *	|  SIGQUIT           |	coredump 	|
 *	|  SIGILL            |	coredump 	|
 *	|  SIGTRAP           |	coredump 	|
 *	|  SIGABRT/SIGIOT    |	coredump 	|
 *	|  SIGBUS            |	coredump 	|
 *	|  SIGFPE            |	coredump 	|
 *	|  SIGKILL           |	terminate(+)	|
 *	|  SIGUSR1           |	terminate	|
 *	|  SIGSEGV           |	coredump 	|
 *	|  SIGUSR2           |	terminate	|
 *	|  SIGPIPE           |	terminate	|
 *	|  SIGALRM           |	terminate	|
 *	|  SIGTERM           |	terminate	|
 *	|  SIGCHLD           |	ignore   	|
 *	|  SIGCONT           |	ignore(*)	|
 *	|  SIGSTOP           |	stop(*)(+)  	|
 *	|  SIGTSTP           |	stop(*)  	|
 *	|  SIGTTIN           |	stop(*)  	|
 *	|  SIGTTOU           |	stop(*)  	|
 *	|  SIGURG            |	ignore   	|
 *	|  SIGXCPU           |	coredump 	|
 *	|  SIGXFSZ           |	coredump 	|
 *	|  SIGVTALRM         |	terminate	|
 *	|  SIGPROF           |	terminate	|
 *	|  SIGPOLL/SIGIO     |	terminate	|
 *	|  SIGSYS/SIGUNUSED  |	coredump 	|
 *	|  SIGSTKFLT         |	terminate	|
 *	|  SIGWINCH          |	ignore   	|
 *	|  SIGPWR            |	terminate	|
 *	|  SIGRTMIN-SIGRTMAX |	terminate       |
 *	+--------------------+------------------+
 *	|  non-POSIX signal  |  default action  |
 *	+--------------------+------------------+
 *	|  SIGEMT            |  coredump	|
 *	+--------------------+------------------+
 *
 * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
 * (*) Special job control effects:
 * When SIGCONT is sent, it resumes the process (all threads in the group)
 * from TASK_STOPPED state and also clears any pending/queued stop signals
 * (any of those marked with "stop(*)").  This happens regardless of blocking,
 * catching, or ignoring SIGCONT.  When any stop signal is sent, it clears
 * any pending/queued SIGCONT signals; this happens regardless of blocking,
 * catching, or ignored the stop signal, though (except for SIGSTOP) the
 * default action of stopping the process may happen later or never.
 */

#ifdef SIGEMT
#define M_SIGEMT	M(SIGEMT)
#else
#define M_SIGEMT	0
#endif

#if SIGRTMIN > BITS_PER_LONG
#define M(sig) (1ULL << ((sig)-1))
#else
#define M(sig) (1UL << ((sig)-1))
#endif
#define T(sig, mask) (M(sig) & (mask))

#define SIG_KERNEL_ONLY_MASK (\
	M(SIGKILL)   |  M(SIGSTOP)                                   )

#define SIG_KERNEL_STOP_MASK (\
	M(SIGSTOP)   |  M(SIGTSTP)   |  M(SIGTTIN)   |  M(SIGTTOU)   )

#define SIG_KERNEL_COREDUMP_MASK (\
        M(SIGQUIT)   |  M(SIGILL)    |  M(SIGTRAP)   |  M(SIGABRT)   | \
        M(SIGFPE)    |  M(SIGSEGV)   |  M(SIGBUS)    |  M(SIGSYS)    | \
        M(SIGXCPU)   |  M(SIGXFSZ)   |  M_SIGEMT                     )

#define SIG_KERNEL_IGNORE_MASK (\
        M(SIGCONT)   |  M(SIGCHLD)   |  M(SIGWINCH)  |  M(SIGURG)    )

#define sig_kernel_only(sig) \
		(((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_ONLY_MASK))
#define sig_kernel_coredump(sig) \
		(((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_COREDUMP_MASK))
#define sig_kernel_ignore(sig) \
		(((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_IGNORE_MASK))
#define sig_kernel_stop(sig) \
		(((sig) < SIGRTMIN)  && T(sig, SIG_KERNEL_STOP_MASK))

#define sig_needs_tasklist(sig)	((sig) == SIGCONT)

#define sig_user_defined(t, signr) \
	(((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_DFL) &&	\
	 ((t)->sighand->action[(signr)-1].sa.sa_handler != SIG_IGN))

#define sig_fatal(t, signr) \
	(!T(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
	 (t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)

static int sig_ignored(struct task_struct *t, int sig)
{
	void __user * handler;

	/*
	 * Tracers always want to know about signals..
	 */
	if (t->ptrace & PT_PTRACED)
		return 0;

	/*
	 * Blocked signals are never ignored, since the
	 * signal handler may change by the time it is
	 * unblocked.
	 */
	if (sigismember(&t->blocked, sig))
		return 0;

	/* Is it explicitly or implicitly ignored? */
	handler = t->sighand->action[sig-1].sa.sa_handler;
	return   handler == SIG_IGN ||
		(handler == SIG_DFL && sig_kernel_ignore(sig));
}

/*
 * Re-calculate pending state from the set of locally pending
 * signals, globally pending signals, and blocked signals.
 */
static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
{
	unsigned long ready;
	long i;

	switch (_NSIG_WORDS) {
	default:
		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
			ready |= signal->sig[i] &~ blocked->sig[i];
		break;

	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
		ready |= signal->sig[2] &~ blocked->sig[2];
		ready |= signal->sig[1] &~ blocked->sig[1];
		ready |= signal->sig[0] &~ blocked->sig[0];
		break;

	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
		ready |= signal->sig[0] &~ blocked->sig[0];
		break;

	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
	}
	return ready !=	0;
}

#define PENDING(p,b) has_pending_signals(&(p)->signal, (b))

fastcall void recalc_sigpending_tsk(struct task_struct *t)
{
	if (t->signal->group_stop_count > 0 ||
	    (freezing(t)) ||
	    PENDING(&t->pending, &t->blocked) ||
	    PENDING(&t->signal->shared_pending, &t->blocked))
		set_tsk_thread_flag(t, TIF_SIGPENDING);
	else
		clear_tsk_thread_flag(t, TIF_SIGPENDING);
}

void recalc_sigpending(void)
{
	recalc_sigpending_tsk(current);
}

/* Given the mask, find the first available signal that should be serviced. */

static int
next_signal(struct sigpending *pending, sigset_t *mask)
{
	unsigned long i, *s, *m, x;
	int sig = 0;
	
	s = pending->signal.sig;
	m = mask->sig;
	switch (_NSIG_WORDS) {
	default:
		for (i = 0; i < _NSIG_WORDS; ++i, ++s, ++m)
			if ((x = *s &~ *m) != 0) {
				sig = ffz(~x) + i*_NSIG_BPW + 1;
				break;
			}
		break;

	case 2: if ((x = s[0] &~ m[0]) != 0)
			sig = 1;
		else if ((x = s[1] &~ m[1]) != 0)
			sig = _NSIG_BPW + 1;
		else
			break;
		sig += ffz(~x);
		break;

	case 1: if ((x = *s &~ *m) != 0)
			sig = ffz(~x) + 1;
		break;
	}
	
	return sig;
}

static struct sigqueue *__sigqueue_alloc(struct task_struct *t, gfp_t flags,
					 int override_rlimit)
{
	struct sigqueue *q = NULL;
	struct user_struct *user;

	/*
	 * In order to avoid problems with "switch_user()", we want to make
	 * sure that the compiler doesn't re-load "t->user"
	 */
	user = t->user;
	barrier();
	atomic_inc(&user->sigpending);
	if (override_rlimit ||
	    atomic_read(&user->sigpending) <=
			t->signal->rlim[RLIMIT_SIGPENDING].rlim_cur)
		q = kmem_cache_alloc(sigqueue_cachep, flags);
	if (unlikely(q == NULL)) {
		atomic_dec(&user->sigpending);
	} else {
		INIT_LIST_HEAD(&q->list);
		q->flags = 0;
		q->user = get_uid(user);
	}
	return(q);
}

static void __sigqueue_free(struct sigqueue *q)
{
	if (q->flags & SIGQUEUE_PREALLOC)
		return;
	atomic_dec(&q->user->sigpending);
	free_uid(q->user);
	kmem_cache_free(sigqueue_cachep, q);
}

void flush_sigqueue(struct sigpending *queue)
{
	struct sigqueue *q;

	sigemptyset(&queue->signal);
	while (!list_empty(&queue->list)) {
		q = list_entry(queue->list.next, struct sigqueue , list);
		list_del_init(&q->list);
		__sigqueue_free(q);
	}
}

/*
 * Flush all pending signals for a task.
 */
void flush_signals(struct task_struct *t)
{
	unsigned long flags;

	spin_lock_irqsave(&t->sighand->siglock, flags);
	clear_tsk_thread_flag(t,TIF_SIGPENDING);
	flush_sigqueue(&t->pending);
	flush_sigqueue(&t->signal->shared_pending);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);
}

/*
 * Flush all handlers for a task.
 */

void
flush_signal_handlers(struct task_struct *t, int force_default)
{
	int i;
	struct k_sigaction *ka = &t->sighand->action[0];
	for (i = _NSIG ; i != 0 ; i--) {
		if (force_default || ka->sa.sa_handler != SIG_IGN)
			ka->sa.sa_handler = SIG_DFL;
		ka->sa.sa_flags = 0;
		sigemptyset(&ka->sa.sa_mask);
		ka++;
	}
}


/* Notify the system that a driver wants to block all signals for this
 * process, and wants to be notified if any signals at all were to be
 * sent/acted upon.  If the notifier routine returns non-zero, then the
 * signal will be acted upon after all.  If the notifier routine returns 0,
 * then then signal will be blocked.  Only one block per process is
 * allowed.  priv is a pointer to private data that the notifier routine
 * can use to determine if the signal should be blocked or not.  */

void
block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
{
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->notifier_mask = mask;
	current->notifier_data = priv;
	current->notifier = notifier;
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

/* Notify the system that blocking has ended. */

void
unblock_all_signals(void)
{
	unsigned long flags;

	spin_lock_irqsave(&current->sighand->siglock, flags);
	current->notifier = NULL;
	current->notifier_data = NULL;
	recalc_sigpending();
	spin_unlock_irqrestore(&current->sighand->siglock, flags);
}

static int collect_signal(int sig, struct sigpending *list, siginfo_t *info)
{
	struct sigqueue *q, *first = NULL;
	int still_pending = 0;

	if (unlikely(!sigismember(&list->signal, sig)))
		return 0;

	/*
	 * Collect the siginfo appropriate to this signal.  Check if
	 * there is another siginfo for the same signal.
	*/
	list_for_each_entry(q, &list->list, list) {
		if (q->info.si_signo == sig) {
			if (first) {
				still_pending = 1;
				break;
			}
			first = q;
		}
	}
	if (first) {
		list_del_init(&first->list);
		copy_siginfo(info, &first->info);
		__sigqueue_free(first);
		if (!still_pending)
			sigdelset(&list->signal, sig);
	} else {

		/* Ok, it wasn't in the queue.  This must be
		   a fast-pathed signal or we must have been
		   out of queue space.  So zero out the info.
		 */
		sigdelset(&list->signal, sig);
		info->si_signo = sig;
		info->si_errno = 0;
		info->si_code = 0;
		info->si_pid = 0;
		info->si_uid = 0;
	}
	return 1;
}

static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
			siginfo_t *info)
{
	int sig = next_signal(pending, mask);

	if (sig) {
		if (current->notifier) {
			if (sigismember(current->notifier_mask, sig)) {
				if (!(current->notifier)(current->notifier_data)) {
					clear_thread_flag(TIF_SIGPENDING);
					return 0;
				}
			}
		}

		if (!collect_signal(sig, pending, info))
			sig = 0;
	}

	return sig;
}

/*
 * Dequeue a signal and return the element to the caller, which is 
 * expected to free it.
 *
 * All callers have to hold the siglock.
 */
int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
{
	int signr = __dequeue_signal(&tsk->pending, mask, info);
	if (!signr)
		signr = __dequeue_signal(&tsk->signal->shared_pending,
					 mask, info);
	recalc_sigpending_tsk(tsk);
 	if (signr && unlikely(sig_kernel_stop(signr))) {
 		/*
 		 * Set a marker that we have dequeued a stop signal.  Our
 		 * caller might release the siglock and then the pending
 		 * stop signal it is about to process is no longer in the
 		 * pending bitmasks, but must still be cleared by a SIGCONT
 		 * (and overruled by a SIGKILL).  So those cases clear this
 		 * shared flag after we've set it.  Note that this flag may
 		 * remain set after the signal we return is ignored or
 		 * handled.  That doesn't matter because its only purpose
 		 * is to alert stop-signal processing code when another
 		 * processor has come along and cleared the flag.
 		 */
 		if (!(tsk->signal->flags & SIGNAL_GROUP_EXIT))
 			tsk->signal->flags |= SIGNAL_STOP_DEQUEUED;
 	}
	if ( signr &&
	     ((info->si_code & __SI_MASK) == __SI_TIMER) &&
	     info->si_sys_private){
		/*
		 * Release the siglock to ensure proper locking order
		 * of timer locks outside of siglocks.  Note, we leave
		 * irqs disabled here, since the posix-timers code is
		 * about to disable them again anyway.
		 */
		spin_unlock(&tsk->sighand->siglock);
		do_schedule_next_timer(info);
		spin_lock(&tsk->sighand->siglock);
	}
	return signr;
}

/*
 * Tell a process that it has a new active signal..
 *
 * NOTE! we rely on the previous spin_lock to
 * lock interrupts for us! We can only be called with
 * "siglock" held, and the local interrupt must
 * have been disabled when that got acquired!
 *
 * No need to set need_resched since signal event passing
 * goes through ->blocked
 */
void signal_wake_up(struct task_struct *t, int resume)
{
	unsigned int mask;

	set_tsk_thread_flag(t, TIF_SIGPENDING);

	/*
	 * For SIGKILL, we want to wake it up in the stopped/traced case.
	 * We don't check t->state here because there is a race with it
	 * executing another processor and just now entering stopped state.
	 * By using wake_up_state, we ensure the process will wake up and
	 * handle its death signal.
	 */
	mask = TASK_INTERRUPTIBLE;
	if (resume)
		mask |= TASK_STOPPED | TASK_TRACED;
	if (!wake_up_state(t, mask))
		kick_process(t);
}

/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 *
 * This version takes a sigset mask and looks at all signals,
 * not just those in the first mask word.
 */
static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
{
	struct sigqueue *q, *n;
	sigset_t m;

	sigandsets(&m, mask, &s->signal);
	if (sigisemptyset(&m))
		return 0;

	signandsets(&s->signal, &s->signal, mask);
	list_for_each_entry_safe(q, n, &s->list, list) {
		if (sigismember(mask, q->info.si_signo)) {
			list_del_init(&q->list);
			__sigqueue_free(q);
		}
	}
	return 1;
}
/*
 * Remove signals in mask from the pending set and queue.
 * Returns 1 if any signals were found.
 *
 * All callers must be holding the siglock.
 */
static int rm_from_queue(unsigned long mask, struct sigpending *s)
{
	struct sigqueue *q, *n;

	if (!sigtestsetmask(&s->signal, mask))
		return 0;

	sigdelsetmask(&s->signal, mask);
	list_for_each_entry_safe(q, n, &s->list, list) {
		if (q->info.si_signo < SIGRTMIN &&
		    (mask & sigmask(q->info.si_signo))) {
			list_del_init(&q->list);
			__sigqueue_free(q);
		}
	}
	return 1;
}

/*
 * Bad permissions for sending the signal
 */
static int check_kill_permission(int sig, struct siginfo *info,
				 struct task_struct *t)
{
	int error = -EINVAL;
	if (!valid_signal(sig))
		return error;
	error = -EPERM;
	if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
	    && ((sig != SIGCONT) ||
		(process_session(current) != process_session(t)))
	    && (current->euid ^ t->suid) && (current->euid ^ t->uid)
	    && (current->uid ^ t->suid) && (current->uid ^ t->uid)
	    && !capable(CAP_KILL))
		return error;

	error = security_task_kill(t, info, sig, 0);
	if (!error)
		audit_signal_info(sig, t); /* Let audit system see the signal */
	return error;
}

/* forward decl */
static void do_notify_parent_cldstop(struct task_struct *tsk, int why);

/*
 * Handle magic process-wide effects of stop/continue signals.
 * Unlike the signal actions, these happen immediately at signal-generation
 * time regardless of blocking, ignoring, or handling.  This does the
 * actual continuing for SIGCONT, but not the actual stopping for stop
 * signals.  The process stop is done as a signal action for SIG_DFL.
 */
static void handle_stop_signal(int sig, struct task_struct *p)
{
	struct task_struct *t;

	if (p->signal->flags & SIGNAL_GROUP_EXIT)
		/*
		 * The process is in the middle of dying already.
		 */
		return;

	if (sig_kernel_stop(sig)) {
		/*
		 * This is a stop signal.  Remove SIGCONT from all queues.
		 */
		rm_from_queue(sigmask(SIGCONT), &p->signal->shared_pending);
		t = p;
		do {
			rm_from_queue(sigmask(SIGCONT), &t->pending);
			t = next_thread(t);
		} while (t != p);
	} else if (sig == SIGCONT) {
		/*
		 * Remove all stop signals from all queues,
		 * and wake all threads.
		 */
		if (unlikely(p->signal->group_stop_count > 0)) {
			/*
			 * There was a group stop in progress.  We'll
			 * pretend it finished before we got here.  We are
			 * obliged to report it to the parent: if the
			 * SIGSTOP happened "after" this SIGCONT, then it
			 * would have cleared this pending SIGCONT.  If it
			 * happened "before" this SIGCONT, then the parent
			 * got the SIGCHLD about the stop finishing before
			 * the continue happened.  We do the notification
			 * now, and it's as if the stop had finished and
			 * the SIGCHLD was pending on entry to this kill.
			 */
			p->signal->group_stop_count = 0;
			p->signal->flags = SIGNAL_STOP_CONTINUED;
			spin_unlock(&p->sighand->siglock);
			do_notify_parent_cldstop(p, CLD_STOPPED);
			spin_lock(&p->sighand->siglock);
		}
		rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
		t = p;
		do {
			unsigned int state;
			rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
			
			/*
			 * If there is a handler for SIGCONT, we must make
			 * sure that no thread returns to user mode before
			 * we post the signal, in case it was the only
			 * thread eligible to run the signal handler--then
			 * it must not do anything between resuming and
			 * running the handler.  With the TIF_SIGPENDING
			 * flag set, the thread will pause and acquire the
			 * siglock that we hold now and until we've queued
			 * the pending signal. 
			 *
			 * Wake up the stopped thread _after_ setting
			 * TIF_SIGPENDING
			 */
			state = TASK_STOPPED;
			if (sig_user_defined(t, SIGCONT) && !sigismember(&t->blocked, SIGCONT)) {
				set_tsk_thread_flag(t, TIF_SIGPENDING);
				state |= TASK_INTERRUPTIBLE;
			}
			wake_up_state(t, state);

			t = next_thread(t);
		} while (t != p);

		if (p->signal->flags & SIGNAL_STOP_STOPPED) {
			/*
			 * We were in fact stopped, and are now continued.
			 * Notify the parent with CLD_CONTINUED.
			 */
			p->signal->flags = SIGNAL_STOP_CONTINUED;
			p->signal->group_exit_code = 0;
			spin_unlock(&p->sighand->siglock);
			do_notify_parent_cldstop(p, CLD_CONTINUED);
			spin_lock(&p->sighand->siglock);
		} else {
			/*
			 * We are not stopped, but there could be a stop
			 * signal in the middle of being processed after
			 * being removed from the queue.  Clear that too.
			 */
			p->signal->flags = 0;
		}
	} else if (sig == SIGKILL) {
		/*
		 * Make sure that any pending stop signal already dequeued
		 * is undone by the wakeup for SIGKILL.
		 */
		p->signal->flags = 0;
	}
}

static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
			struct sigpending *signals)
{
	struct sigqueue * q = NULL;
	int ret = 0;

	/*
	 * fast-pathed signals for kernel-internal things like SIGSTOP
	 * or SIGKILL.
	 */
	if (info == SEND_SIG_FORCED)
		goto out_set;

	/* Real-time signals must be queued if sent by sigqueue, or
	   some other real-time mechanism.  It is implementation
	   defined whether kill() does so.  We attempt to do so, on
	   the principle of least surprise, but since kill is not
	   allowed to fail with EAGAIN when low on memory we just
	   make sure at least one signal gets delivered and don't
	   pass on the info struct.  */

	q = __sigqueue_alloc(t, GFP_ATOMIC, (sig < SIGRTMIN &&
					     (is_si_special(info) ||
					      info->si_code >= 0)));
	if (q) {
		list_add_tail(&q->list, &signals->list);
		switch ((unsigned long) info) {
		case (unsigned long) SEND_SIG_NOINFO:
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_USER;
			q->info.si_pid = current->pid;
			q->info.si_uid = current->uid;
			break;
		case (unsigned long) SEND_SIG_PRIV:
			q->info.si_signo = sig;
			q->info.si_errno = 0;
			q->info.si_code = SI_KERNEL;
			q->info.si_pid = 0;
			q->info.si_uid = 0;
			break;
		default:
			copy_siginfo(&q->info, info);
			break;
		}
	} else if (!is_si_special(info)) {
		if (sig >= SIGRTMIN && info->si_code != SI_USER)
		/*
		 * Queue overflow, abort.  We may abort if the signal was rt
		 * and sent by user using something other than kill().
		 */
			return -EAGAIN;
	}

out_set:
	sigaddset(&signals->signal, sig);
	return ret;
}

#define LEGACY_QUEUE(sigptr, sig) \
	(((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))


static int
specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	int ret = 0;

	BUG_ON(!irqs_disabled());
	assert_spin_locked(&t->sighand->siglock);

	/* Short-circuit ignored signals.  */
	if (sig_ignored(t, sig))
		goto out;

	/* Support queueing exactly one non-rt signal, so that we
	   can get more detailed information about the cause of
	   the signal. */
	if (LEGACY_QUEUE(&t->pending, sig))
		goto out;

	ret = send_signal(sig, info, t, &t->pending);
	if (!ret && !sigismember(&t->blocked, sig))
		signal_wake_up(t, sig == SIGKILL);
out:
	return ret;
}

/*
 * Force a signal that the process can't ignore: if necessary
 * we unblock the signal and change any SIG_IGN to SIG_DFL.
 *
 * Note: If we unblock the signal, we always reset it to SIG_DFL,
 * since we do not want to have a signal handler that was blocked
 * be invoked when user space had explicitly blocked it.
 *
 * We don't want to have recursive SIGSEGV's etc, for example.
 */
int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{
	unsigned long int flags;
	int ret, blocked, ignored;
	struct k_sigaction *action;

	spin_lock_irqsave(&t->sighand->siglock, flags);
	action = &t->sighand->action[sig-1];
	ignored = action->sa.sa_handler == SIG_IGN;
	blocked = sigismember(&t->blocked, sig);
	if (blocked || ignored) {
		action->sa.sa_handler = SIG_DFL;
		if (blocked) {
			sigdelset(&t->blocked, sig);
			recalc_sigpending_tsk(t);
		}
	}
	ret = specific_send_sig_info(sig, info, t);
	spin_unlock_irqrestore(&t->sighand->siglock, flags);

	return ret;
}

void
force_sig_specific(int sig, struct task_struct *t)
{
	force_sig_info(sig, SEND_SIG_FORCED, t);
}

/*
 * Test if P wants to take SIG.  After we've checked all threads with this,
 * it's equivalent to finding no threads not blocking SIG.  Any threads not
 * blocking SIG were ruled out because they are not running and already
 * have pending signals.  Such threads will dequeue from the shared queue
 * as soon as they're available, so putting the signal on the shared queue
 * will be equivalent to sending it to one such thread.
 */
static inline int wants_signal(int sig, struct task_struct *p)
{
	if (sigismember(&p->blocked, sig))
		return 0;
	if (p->flags & PF_EXITING)
		return 0;
	if (sig == SIGKILL)
		return 1;
	if (p->state & (TASK_STOPPED | TASK_TRACED))
		return 0;
	return task_curr(p) || !signal_pending(p);
}

static void
__group_complete_signal(int sig, struct task_struct *p)
{
	struct task_struct *t;

	/*
	 * Now find a thread we can wake up to take the signal off the queue.
	 *
	 * If the main thread wants the signal, it gets first crack.
	 * Probably the least surprising to the average bear.
	 */
	if (wants_signal(sig, p))
		t = p;
	else if (thread_group_empty(p))
		/*
		 * There is just one thread and it does not need to be woken.
		 * It will dequeue unblocked signals before it runs again.
		 */
		return;
	else {
		/*
		 * Otherwise try to find a suitable thread.
		 */
		t = p->signal->curr_target;
		if (t == NULL)
			/* restart balancing at this thread */
			t = p->signal->curr_target = p;

		while (!wants_signal(sig, t)) {
			t = next_thread(t);
			if (t == p->signal->curr_target)
				/*
				 * No thread needs to be woken.
				 * Any eligible threads will see
				 * the signal in the queue soon.
				 */
				return;
		}
		p->signal->curr_target = t;
	}

	/*
	 * Found a killable thread.  If the signal will be fatal,
	 * then start taking the whole group down immediately.
	 */
	if (sig_fatal(p, sig) && !(p->signal->flags & SIGNAL_GROUP_EXIT) &&
	    !sigismember(&t->real_blocked, sig) &&
	    (sig == SIGKILL || !(t->ptrace & PT_PTRACED))) {
		/*
		 * This signal will be fatal to the whole group.
		 */
		if (!sig_kernel_coredump(sig)) {
			/*
			 * Start a group exit and wake everybody up.
			 * This way we don't have other threads
			 * running and doing things after a slower
			 * thread has the fatal signal pending.
			 */
			p->signal->flags = SIGNAL_GROUP_EXIT;
			p->signal->group_exit_code = sig;
			p->signal->group_stop_count = 0;
			t = p;
			do {
				sigaddset(&t->pending.signal, SIGKILL);
				signal_wake_up(t, 1);
				t = next_thread(t);
			} while (t != p);
			return;
		}

		/*
		 * There will be a core dump.  We make all threads other
		 * than the chosen one go into a group stop so that nothing
		 * happens until it gets scheduled, takes the signal off
		 * the shared queue, and does the core dump.  This is a
		 * little more complicated than strictly necessary, but it
		 * keeps the signal state that winds up in the core dump
		 * unchanged from the death state, e.g. which thread had
		 * the core-dump signal unblocked.
		 */
		rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
		rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending);
		p->signal->group_stop_count = 0;
		p->signal->group_exit_task = t;
		t = p;
		do {
			p->signal->group_stop_count++;
			signal_wake_up(t, 0);
			t = next_thread(t);
		} while (t != p);
		wake_up_process(p->signal->group_exit_task);
		return;
	}

	/*
	 * The signal is already in the shared-pending queue.
	 * Tell the chosen thread to wake up and dequeue it.
	 */
	signal_wake_up(t, sig == SIGKILL);
	return;
}

int
__group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
	int ret = 0;

	assert_spin_locked(&p->sighand->siglock);
	handle_stop_signal(sig, p);

	/* Short-circuit ignored signals.  */
	if (sig_ignored(p, sig))
		return ret;

	if (LEGACY_QUEUE(&p->signal->shared_pending, sig))
		/* This is a non-RT signal and we already have one queued.  */
		return ret;

	/*
	 * Put this signal on the shared-pending queue, or fail with EAGAIN.
	 * We always use the shared queue for process-wide signals,
	 * to avoid several races.
	 */
	ret = send_signal(sig, info, p, &p->signal->shared_pending);
	if (unlikely(ret))
		return ret;

	__group_complete_signal(sig, p);
	return 0;
}

/*
 * Nuke all other threads in the group.
 */
void zap_other_threads(struct task_struct *p)
{
	struct task_struct *t;

	p->signal->flags = SIGNAL_GROUP_EXIT;
	p->signal->group_stop_count = 0;

	if (thread_group_empty(p))
		return;

	for (t = next_thread(p); t != p; t = next_thread(t)) {
		/*
		 * Don't bother with already dead threads
		 */
		if (t->exit_state)
			continue;

		/*
		 * We don't want to notify the parent, since we are
		 * killed as part of a thread group due to another
		 * thread doing an execve() or similar. So set the
		 * exit signal to -1 to allow immediate reaping of
		 * the process.  But don't detach the thread group
		 * leader.
		 */
		if (t != p->group_leader)
			t->exit_signal = -1;

		/* SIGKILL will be handled before any pending SIGSTOP */
		sigaddset(&t->pending.signal, SIGKILL);
		signal_wake_up(t, 1);
	}
}

/*
 * Must be called under rcu_read_lock() or with tasklist_lock read-held.
 */
struct sighand_struct *lock_task_sighand(struct task_struct *tsk, unsigned long *flags)
{
	struct sighand_struct *sighand;

	for (;;) {
		sighand = rcu_dereference(tsk->sighand);
		if (unlikely(sighand == NULL))
			break;

		spin_lock_irqsave(&sighand->siglock, *flags);
		if (likely(sighand == tsk->sighand))
			break;
		spin_unlock_irqrestore(&sighand->siglock, *flags);
	}

	return sighand;
}

int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
{
	unsigned long flags;
	int ret;

	ret = check_kill_permission(sig, info, p);

	if (!ret && sig) {
		ret = -ESRCH;
		if (lock_task_sighand(p, &flags)) {
			ret = __group_send_sig_info(sig, info, p);
			unlock_task_sighand(p, &flags);
		}
	}

	return ret;
}

/*
 * kill_pgrp_info() sends a signal to a process group: this is what the tty
 * control characters do (^C, ^Z etc)
 */

int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
{
	struct task_struct *p = NULL;
	int retval, success;

	success = 0;
	retval = -ESRCH;
	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
		int err = group_send_sig_info(sig, info, p);
		success |= !err;
		retval = err;
	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
	return success ? 0 : retval;
}

int kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
{
	int retval;

	read_lock(&tasklist_lock);
	retval = __kill_pgrp_info(sig, info, pgrp);
	read_unlock(&tasklist_lock);

	return retval;
}

int __kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
{
	if (pgrp <= 0)
		return -EINVAL;

	return __kill_pgrp_info(sig, info, find_pid(pgrp));
}

int
kill_pg_info(int sig, struct siginfo *info, pid_t pgrp)
{
	int retval;

	read_lock(&tasklist_lock);
	retval = __kill_pg_info(sig, info, pgrp);
	read_unlock(&tasklist_lock);

	return retval;
}

int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
{
	int error;
	int acquired_tasklist_lock = 0;
	struct task_struct *p;

	rcu_read_lock();
	if (unlikely(sig_needs_tasklist(sig))) {
		read_lock(&tasklist_lock);
		acquired_tasklist_lock = 1;
	}
	p = pid_task(pid, PIDTYPE_PID);
	error = -ESRCH;
	if (p)
		error = group_send_sig_info(sig, info, p);
	if (unlikely(acquired_tasklist_lock))
		read_unlock(&tasklist_lock);
	rcu_read_unlock();
	return error;
}

static int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
{
	int error;
	rcu_read_lock();
	error = kill_pid_info(sig, info, find_pid(pid));
	rcu_read_unlock();
	return error;
}

/* like kill_pid_info(), but doesn't use uid/euid of "current" */
int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
		      uid_t uid, uid_t euid, u32 secid)
{
	int ret = -EINVAL;
	struct task_struct *p;

	if (!valid_signal(sig))
		return ret;

	read_lock(&tasklist_lock);
	p = pid_task(pid, PIDTYPE_PID);
	if (!p) {
		ret = -ESRCH;
		goto out_unlock;
	}
	if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
	    && (euid != p->suid) && (euid != p->uid)
	    && (uid != p->suid) && (uid != p->uid)) {
		ret = -EPERM;
		goto out_unlock;
	}
	ret = security_task_kill(p, info, sig, secid);
	if (ret)
		goto out_unlock;
	if (sig && p->sighand) {
		unsigned long flags;
		spin_lock_irqsave(&p->sighand->siglock, flags);
		ret = __group_send_sig_info(sig, info, p);
		spin_unlock_irqrestore(&p->sighand->siglock, flags);
	}
out_unlock:
	read_unlock(&tasklist_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);

/*
 * kill_something_info() interprets pid in interesting ways just like kill(2).
 *
 * POSIX specifies that kill(-1,sig) is unspecified, but what we have
 * is probably wrong.  Should make it like BSD or SYSV.
 */

static int kill_something_info(int sig, struct siginfo *info, int pid)
{
	if (!pid) {
		return kill_pg_info(sig, info, process_group(current));
	} else if (pid == -1) {
		int retval = 0, count = 0;
		struct task_struct * p;

		read_lock(&tasklist_lock);
		for_each_process(p) {
			if (p->pid > 1 && p->tgid != current->tgid) {
				int err = group_send_sig_info(sig, info, p);
				++count;
				if (err != -EPERM)
					retval = err;
			}
		}
		read_unlock(&tasklist_lock);
		return count ? retval : -ESRCH;