Char: cyclades, remove bottom half processing

The work done in bottom half doesn't cost much cpu time (e.g.  tty_hangup
itself schedules its own bottom half), it's possible to do the work in isr
directly and save hence some .text.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 20 insertions, 106 deletions

diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index 9e0adfe27c12..817fef3071af 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -897,71 +897,6 @@ static inline int serial_paranoia_check(struct cyclades_port *info,
         return 0;
 }                               /* serial_paranoia_check */
 
-/*
- * This routine is used by the interrupt handler to schedule
- * processing in the software interrupt portion of the driver
- * (also known as the "bottom half").  This can be called any
- * number of times for any channel without harm.
- */
-static inline void cy_sched_event(struct cyclades_port *info, int event)
-{
-        info->event |= 1 << event; /* remember what kind of event and who */
-        schedule_work(&info->tqueue);
-}                               /* cy_sched_event */
-
-/*
- * This routine is used to handle the "bottom half" processing for the
- * serial driver, known also the "software interrupt" processing.
- * This processing is done at the kernel interrupt level, after the
- * cy#/_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
- * is where time-consuming activities which can not be done in the
- * interrupt driver proper are done; the interrupt driver schedules
- * them using cy_sched_event(), and they get done here.
- *
- * This is done through one level of indirection--the task queue.
- * When a hardware interrupt service routine wants service by the
- * driver's bottom half, it enqueues the appropriate tq_struct (one
- * per port) to the keventd work queue and sets a request flag
- * that the work queue be processed.
- *
- * Although this may seem unwieldy, it gives the system a way to
- * pass an argument (in this case the pointer to the cyclades_port
- * structure) to the bottom half of the driver.  Previous kernels
- * had to poll every port to see if that port needed servicing.
- */
-static void
-do_softint(struct work_struct *work)
-{
-        struct cyclades_port *info =
-                container_of(work, struct cyclades_port, tqueue);
-        struct tty_struct    *tty;
-
-        tty = info->tty;
-        if (!tty)
-                return;
-
-        if (test_and_clear_bit(Cy_EVENT_HANGUP, &info->event)) {
-                tty_hangup(info->tty);
-                wake_up_interruptible(&info->open_wait);
-                        info->flags &= ~ASYNC_NORMAL_ACTIVE;
-        }
-        if (test_and_clear_bit(Cy_EVENT_OPEN_WAKEUP, &info->event))
-                wake_up_interruptible(&info->open_wait);
-#ifdef CONFIG_CYZ_INTR
-        if (test_and_clear_bit(Cy_EVENT_Z_RX_FULL, &info->event) &&
-                        !timer_pending(&cyz_rx_full_timer[info->line]))
-                mod_timer(&cyz_rx_full_timer[info->line], jiffies + 1);
-#endif
-        if (test_and_clear_bit(Cy_EVENT_DELTA_WAKEUP, &info->event))
-                wake_up_interruptible(&info->delta_msr_wait);
-        tty_wakeup(tty);
-#ifdef Z_WAKE
-        if (test_and_clear_bit(Cy_EVENT_SHUTDOWN_WAKEUP, &info->event))
-                complete(&info->shutdown_wait);
-#endif
-} /* do_softint */
-
-
 /***********************************************************/
 /********* Start of block of Cyclom-Y specific code ********/
 
@@ -1243,7 +1178,7 @@ static void cyy_intr_chip(struct cyclades_card *cinfo, int chip,
                         cy_writeb(base_addr + (CySRER << index),
                                   readb(base_addr + (CySRER << index)) &
                                   ~CyTxRdy);
-                        goto txdone;
+                        goto txend;
                 }
 
                 /* load the on-chip space for outbound data */
@@ -1334,9 +1269,7 @@ static void cyy_intr_chip(struct cyclades_card *cinfo, int chip,
                 }
 
 txdone:
-                if (info->xmit_cnt < WAKEUP_CHARS) {
-                        cy_sched_event(info, Cy_EVENT_WRITE_WAKEUP);
-                }
+                tty_wakeup(info->tty);
 txend:
                 /* end of service */
                 cy_writeb(base_addr + (CyTIR << index), (save_xir & 0x3f));
@@ -1369,17 +1302,16 @@ txend:
                                 if (mdm_change & CyRI)
                                         info->icount.rng++;
 
-                                cy_sched_event(info, Cy_EVENT_DELTA_WAKEUP);
+                                wake_up_interruptible(&info->delta_msr_wait);
                         }
 
                         if ((mdm_change & CyDCD) &&
                                         (info->flags & ASYNC_CHECK_CD)) {
-                                if (mdm_status & CyDCD) {
-                                        cy_sched_event(info,
-                                                        Cy_EVENT_OPEN_WAKEUP);
-                                } else {
-                                        cy_sched_event(info, Cy_EVENT_HANGUP);
+                                if (!(mdm_status & CyDCD)) {
+                                        tty_hangup(info->tty);
+                                        info->flags &= ~ASYNC_NORMAL_ACTIVE;
                                 }
+                                wake_up_interruptible(&info->open_wait);
                         }
                         if ((mdm_change & CyCTS) &&
                                         (info->flags & ASYNC_CTS_FLOW)) {
@@ -1394,8 +1326,7 @@ txend:
                                                                 (CySRER <<
                                                                         index))|
                                                         CyTxRdy);
-                                                cy_sched_event(info,
-                                                        Cy_EVENT_WRITE_WAKEUP);
+                                                tty_wakeup(info->tty);
                                         }
                                 } else {
                                         if (!(mdm_status & CyCTS)) {
@@ -1633,9 +1564,11 @@ cyz_handle_rx(struct cyclades_port *info, struct CH_CTRL __iomem *ch_ctrl,
                                 char_count = rx_put - rx_get;
                         else
                                 char_count = rx_put - rx_get + rx_bufsize;
-                        if (char_count >= (int)readl(&buf_ctrl->rx_threshold)) {
-                                cy_sched_event(info, Cy_EVENT_Z_RX_FULL);
-                        }
+                        if (char_count >= (int)readl(&buf_ctrl->rx_threshold) &&
+                                        !timer_pending(&cyz_rx_full_timer[
+                                                        info->line]))
+                                mod_timer(&cyz_rx_full_timer[info->line],
+                                                jiffies + 1);
 #endif
                         info->idle_stats.recv_idle = jiffies;
                         tty_schedule_flip(tty);
@@ -1717,9 +1650,7 @@ cyz_handle_tx(struct cyclades_port *info, struct CH_CTRL __iomem *ch_ctrl,
                 }
 #endif
 ztxdone:
-                if (info->xmit_cnt < WAKEUP_CHARS) {
-                        cy_sched_event(info, Cy_EVENT_WRITE_WAKEUP);
-                }
+                tty_wakeup(tty);
                 /* Update tx_put */
                 cy_writel(&buf_ctrl->tx_put, tx_put);
         }
@@ -1781,10 +1712,11 @@ static void cyz_handle_cmd(struct cyclades_card *cinfo)
                                 if ((fw_ver > 241 ? ((u_long) param) :
                                                 readl(&ch_ctrl->rs_status)) &
                                                 C_RS_DCD) {
-                                        cy_sched_event(info,
-                                                        Cy_EVENT_OPEN_WAKEUP);
+                                        wake_up_interruptible(&info->open_wait);
                                 } else {
-                                        cy_sched_event(info, Cy_EVENT_HANGUP);
+                                        tty_hangup(info->tty);
+                                        wake_up_interruptible(&info->open_wait);
+                                        info->flags &= ~ASYNC_NORMAL_ACTIVE;
                                 }
                         }
                         break;
@@ -1802,7 +1734,7 @@ static void cyz_handle_cmd(struct cyclades_card *cinfo)
                         break;
 #ifdef Z_WAKE
                 case C_CM_IOCTLW:
-                        cy_sched_event(info, Cy_EVENT_SHUTDOWN_WAKEUP);
+                        complete(&info->shutdown_wait);
                         break;
 #endif
 #ifdef CONFIG_CYZ_INTR
@@ -1834,7 +1766,7 @@ static void cyz_handle_cmd(struct cyclades_card *cinfo)
                         break;
                 }
                 if (delta_count)
-                        cy_sched_event(info, Cy_EVENT_DELTA_WAKEUP);
+                        wake_up_interruptible(&info->delta_msr_wait);
                 if (special_count)
                         tty_schedule_flip(tty);
         }
@@ -2812,7 +2744,6 @@ static void cy_close(struct tty_struct *tty, struct file *filp)
         spin_lock_irqsave(&card->card_lock, flags);
 
         tty->closing = 0;
-        info->event = 0;
         info->tty = NULL;
         if (info->blocked_open) {
                 spin_unlock_irqrestore(&card->card_lock, flags);
@@ -4444,7 +4375,6 @@ static void cy_hangup(struct tty_struct *tty)
 
         cy_flush_buffer(tty);
         shutdown(info);
-        info->event = 0;
         info->count = 0;
 #ifdef CY_DEBUG_COUNT
         printk(KERN_DEBUG "cyc:cy_hangup (%d): setting count to 0\n",
@@ -4502,7 +4432,6 @@ static int __devinit cy_init_card(struct cyclades_card *cinfo)
                 info->closing_wait = CLOSING_WAIT_DELAY;
                 info->close_delay = 5 * HZ / 10;
 
-                INIT_WORK(&info->tqueue, do_softint);
                 init_waitqueue_head(&info->open_wait);
                 init_waitqueue_head(&info->close_wait);
                 init_completion(&info->shutdown_wait);
diff --git a/include/linux/cyclades.h b/include/linux/cyclades.h
index 72aa00cc4b2d..06b272590776 100644
--- a/include/linux/cyclades.h
+++ b/include/linux/cyclades.h
@@ -569,7 +569,6 @@ struct cyclades_port {
         int                     x_char; /* to be pushed out ASAP */
         int                     close_delay;
         unsigned short          closing_wait;
-        unsigned long           event;
         int                     count;  /* # of fd on device */
         int                     breakon;
         int                     breakoff;
@@ -584,7 +583,6 @@ struct cyclades_port {
         struct cyclades_monitor mon;
         struct cyclades_idle_stats      idle_stats;
         struct cyclades_icount  icount;
-        struct work_struct      tqueue;
         wait_queue_head_t       open_wait;
         wait_queue_head_t       close_wait;
         struct completion       shutdown_wait;
@@ -592,19 +590,6 @@ struct cyclades_port {
         int throttle;
 };
 
-/*
- * Events are used to schedule things to happen at timer-interrupt
- * time, instead of at cy interrupt time.
- */
-#define Cy_EVENT_READ_PROCESS           0
-#define Cy_EVENT_WRITE_WAKEUP           1
-#define Cy_EVENT_HANGUP                 2
-#define Cy_EVENT_BREAK                  3
-#define Cy_EVENT_OPEN_WAKEUP            4
-#define Cy_EVENT_SHUTDOWN_WAKEUP        5
-#define Cy_EVENT_DELTA_WAKEUP           6
-#define Cy_EVENT_Z_RX_FULL              7
-
 #define CLOSING_WAIT_DELAY      30*HZ
 #define CY_CLOSING_WAIT_NONE    65535
 #define CY_CLOSING_WAIT_INF     0