0 files changed, 0 insertions, 0 deletions

path: root/drivers/mtd/ubi/cdev.c

/*
 *  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/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/signalfd.h>
#include <linux/ratelimit.h>
#include <linux/tracehook.h>
#include <linux/capability.h>
#include <linux/freezer.h>
#include <linux/pid_namespace.h>
#include <linux/nsproxy.h>
#define CREATE_TRACE_POINTS
#include <trace/events/signal.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;

int print_fatal_signals __read_mostly;

static void __user *sig_handler(struct task_struct *t, int sig)
{
	return t->sighand->action[sig - 1].sa.sa_handler;
}

static int sig_handler_ignored(void __user *handler, int sig)
{
	/* Is it explicitly or implicitly ignored? */
	return handler == SIG_IGN ||
		(handler == SIG_DFL && sig_kernel_ignore(sig));
}

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

	handler = sig_handler(t, sig);

	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
			handler == SIG_DFL && !from_ancestor_ns)
		return 1;

	return sig_handler_ignored(handler, sig);
}

static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
{
	/*
	 * Blocked signals are never ignored, since the
	 * signal handler may change by the time it is
	 * unblocked.
	 */
	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
		return 0;

	if (!sig_task_ignored(t, sig, from_ancestor_ns))
		return 0;

	/*
	 * Tracers may want to know about even ignored signals.
	 */
	return !tracehook_consider_ignored_signal(t, 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))

static int recalc_sigpending_tsk(struct task_struct *t)
{
	if (t->signal->group_stop_count > 0 ||
	    PENDING(&t->pending, &t->blocked) ||
	    PENDING(&t->signal->shared_pending, &t->blocked)) {
		set_tsk_thread_flag(t, TIF_SIGPENDING);
		return 1;
	}
	/*
	 * We must never clear the flag in another thread, or in current
	 * when it's possible the current syscall is returning -ERESTART*.
	 * So we don't clear it here, and only callers who know they should do.
	 */
	return 0;
}

/*
 * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
 * This is superfluous when called on current, the wakeup is a harmless no-op.
 */
void recalc_sigpending_and_wake(struct task_struct *t)
{
	if (recalc_sigpending_tsk(t))
		signal_wake_up(t, 0);
}

void recalc_sigpending(void)
{
	if (unlikely(tracehook_force_sigpending()))
		set_thread_flag(TIF_SIGPENDING);
	else if (!recalc_sigpending_tsk(current) && !freezing(current))
		clear_thread_flag(TIF_SIGPENDING);

}

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

#define SYNCHRONOUS_MASK \
	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
	 sigmask(SIGTRAP) | sigmask(SIGFPE))

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;

	/*
	 * Handle the first word specially: it contains the
	 * synchronous signals that need to be dequeued first.
	 */
	x = *s &~ *m;
	if (x) {
		if (x & SYNCHRONOUS_MASK)
			x &= SYNCHRONOUS_MASK;
		sig = ffz(~x) + 1;
		return sig;
	}

	switch (_NSIG_WORDS) {
	default:
		for (i = 1; i < _NSIG_WORDS; ++i) {
			x = *++s &~ *++m;
			if (!x)
				continue;
			sig = ffz(~x) + i*_NSIG_BPW + 1;
			break;
		}
		break;

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

	case 1:
		/* Nothing to do */
		break;
	}

	return sig;
}

static inline void print_dropped_signal(int sig)
{
	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);

	if (!print_fatal_signals)
		return;

	if (!__ratelimit(&ratelimit_state))
		return;

	printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
				current->comm, current->pid, sig);
}

/*
 * allocate a new signal queue record
 * - this may be called without locks if and only if t == current, otherwise an
 *   appopriate lock must be held to stop the target task from exiting
 */
static struct sigqueue *
__sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
{
	struct sigqueue *q = NULL;
	struct user_struct *user;

	/*
	 * Protect access to @t credentials. This can go away when all
	 * callers hold rcu read lock.
	 */
	rcu_read_lock();
	user = get_uid(__task_cred(t)->user);
	atomic_inc(&user->sigpending);
	rcu_read_unlock();

	if (override_rlimit ||
	    atomic_read(&user->sigpending) <=
			task_rlimit(t, RLIMIT_SIGPENDING)) {
		q = kmem_cache_alloc(sigqueue_cachep, flags);
	} else {
		print_dropped_signal(sig);
	}

	if (unlikely(q == NULL)) {
		atomic_dec(&user->sigpending);
		free_uid(user);
	} else {
		INIT_LIST_HEAD(&q->list);
		q->flags = 0;
		q->user = 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)
{
	clear_tsk_thread_flag(t, TIF_SIGPENDING);
	flush_sigqueue(&t->pending);
	flush_sigqueue(&t->signal->shared_pending);
}

void flush_signals(struct task_struct *t)
{
	unsigned long flags;

	spin_lock_irqsave(&t->sighand->siglock, flags);