[PATCH] kthread: airo.c

The airo driver is currently caching a pid for later use, but with the
implementation of containers, pids themselves do not uniquely identify a
task.  The driver is also using kernel_thread() which is deprecated in
drivers.

This patch essentially replaces the kernel_thread() with kthread_create().
It also stores the task_struct of the airo_thread rather than its pid.
Since this introduces a second task_struct in struct airo_info, the patch
renames airo_info.task to airo_info.list_bss_task.

As an extension of these changes, the patch further:

	 - replaces kill_proc() with kthread_stop()
	 - replaces signal_pending() with kthread_should_stop()
	 - removes thread completion synchronisation which is handled by
	   kthread_stop().

[akpm@osdl.org: fix races]
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Javier Achirica <achirica@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 16 insertions, 24 deletions

diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 16befbcea58c..e088ceefb4a3 100644
--- a/drivers/net/wireless/airo.c
+++ b/drivers/net/wireless/airo.c
@@ -47,6 +47,7 @@
 #include <linux/pci.h>
 #include <asm/uaccess.h>
 #include <net/ieee80211.h>
+#include <linux/kthread.h>
 
 #include "airo.h"
 
@@ -1187,11 +1188,10 @@ struct airo_info {
                         int whichbap);
         unsigned short *flash;
         tdsRssiEntry *rssi;
-        struct task_struct *task;
+        struct task_struct *list_bss_task;
+        struct task_struct *airo_thread_task;
         struct semaphore sem;
-        pid_t thr_pid;
         wait_queue_head_t thr_wait;
-        struct completion thr_exited;
         unsigned long expires;
         struct {
                 struct sk_buff *skb;
@@ -1733,12 +1733,12 @@ static int readBSSListRid(struct airo_info *ai, int first,
                 cmd.cmd=CMD_LISTBSS;
                 if (down_interruptible(&ai->sem))
                         return -ERESTARTSYS;
+                ai->list_bss_task = current;
                 issuecommand(ai, &cmd, &rsp);
                 up(&ai->sem);
                 /* Let the command take effect */
-                ai->task = current;
-                ssleep(3);
-                ai->task = NULL;
+                schedule_timeout_uninterruptible(3 * HZ);
+                ai->list_bss_task = NULL;
         }
         rc = PC4500_readrid(ai, first ? ai->bssListFirst : ai->bssListNext,
                             list, ai->bssListRidLen, 1);
@@ -2400,8 +2400,7 @@ void stop_airo_card( struct net_device *dev, int freeres )
                 clear_bit(FLAG_REGISTERED, &ai->flags);
         }
         set_bit(JOB_DIE, &ai->jobs);
-        kill_proc(ai->thr_pid, SIGTERM, 1);
-        wait_for_completion(&ai->thr_exited);
+        kthread_stop(ai->airo_thread_task);
 
         /*
          * Clean out tx queue
@@ -2811,9 +2810,8 @@ static struct net_device *_init_airo_card( unsigned short irq, int port,
         ai->config.len = 0;
         ai->pci = pci;
         init_waitqueue_head (&ai->thr_wait);
-        init_completion (&ai->thr_exited);
-        ai->thr_pid = kernel_thread(airo_thread, dev, CLONE_FS | CLONE_FILES);
-        if (ai->thr_pid < 0)
+        ai->airo_thread_task = kthread_run(airo_thread, dev, dev->name);
+        if (IS_ERR(ai->airo_thread_task))
                 goto err_out_free;
         ai->tfm = NULL;
         rc = add_airo_dev( dev );
@@ -2930,8 +2928,7 @@ err_out_unlink:
         del_airo_dev(dev);
 err_out_thr:
         set_bit(JOB_DIE, &ai->jobs);
-        kill_proc(ai->thr_pid, SIGTERM, 1);
-        wait_for_completion(&ai->thr_exited);
+        kthread_stop(ai->airo_thread_task);
 err_out_free:
         free_netdev(dev);
         return NULL;
@@ -3063,13 +3060,7 @@ static int airo_thread(void *data) {
         struct airo_info *ai = dev->priv;
         int locked;
         
-        daemonize("%s", dev->name);
-        allow_signal(SIGTERM);
-
         while(1) {
-                if (signal_pending(current))
-                        flush_signals(current);
-
                 /* make swsusp happy with our thread */
                 try_to_freeze();
 
@@ -3097,7 +3088,7 @@ static int airo_thread(void *data) {
                                                 set_bit(JOB_AUTOWEP, &ai->jobs);
                                                 break;
                                         }
-                                        if (!signal_pending(current)) {
+                                        if (!kthread_should_stop()) {
                                                 unsigned long wake_at;
                                                 if (!ai->expires || !ai->scan_timeout) {
                                                         wake_at = max(ai->expires,
@@ -3109,7 +3100,7 @@ static int airo_thread(void *data) {
                                                 schedule_timeout(wake_at - jiffies);
                                                 continue;
                                         }
-                                } else if (!signal_pending(current)) {
+                                } else if (!kthread_should_stop()) {
                                         schedule();
                                         continue;
                                 }
@@ -3154,7 +3145,8 @@ static int airo_thread(void *data) {
                 else  /* Shouldn't get here, but we make sure to unlock */
                         up(&ai->sem);
         }
-        complete_and_exit (&ai->thr_exited, 0);
+
+        return 0;
 }
 
 static irqreturn_t airo_interrupt ( int irq, void* dev_id, struct pt_regs *regs) {
@@ -3235,8 +3227,8 @@ static irqreturn_t airo_interrupt ( int irq, void* dev_id, struct pt_regs *regs)
                         if(newStatus == ASSOCIATED || newStatus == REASSOCIATED) {
                                 if (auto_wep)
                                         apriv->expires = 0;
-                                if (apriv->task)
-                                        wake_up_process (apriv->task);
+                                if (apriv->list_bss_task)
+                                        wake_up_process(apriv->list_bss_task);
                                 set_bit(FLAG_UPDATE_UNI, &apriv->flags);
                                 set_bit(FLAG_UPDATE_MULTI, &apriv->flags);