[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>

diff --git a/drivers/net/wireless/airo.c b/drivers/net/wireless/airo.c
index 16befbcea58cb71ed901c4826456c32e36e17034..e088ceefb4a35468918fe059e129ab497fbc2ac4 100644 (file)
--- 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);