[Scst-devel] [PATCH] scst_fileio thread/module shutdown

[Arne R. <arn...@xi...>]

Use a completion instead of waiting an arbitrary amount of time (1s) to
make sure the threads are really gone.

Only mildly tested, but I didn't run into any troubles. Mostly because
the threads usually exited quite early, i.e. the while(atomic_read())
loop wasn't even entered.

Any feedback is welcome.

Signed-off-by: Arne Redlich <arn...@xi...>

Index: src/dev_handlers/scst_fileio.c
===================================================================
RCS file: /cvsroot/scst/src/dev_handlers/scst_fileio.c,v
retrieving revision 1.29
diff -a -u -p -r1.29 scst_fileio.c
--- src/dev_handlers/scst_fileio.c	10 Jun 2006 16:05:28 -0000	1.29
+++ src/dev_handlers/scst_fileio.c	2 Jul 2006 18:58:54 -0000
@@ -110,6 +110,7 @@ struct scst_fileio_tgt_dev {
 	atomic_t threads_count;
 	struct semaphore shutdown_mutex;
 	struct list_head ftgt_list_entry;
+	struct completion done;
 };
 
 static int fileio_attach(struct scst_device *dev);
@@ -582,6 +583,7 @@ static int fileio_cmd_thread(void *arg)
 		up(&ftgt_dev->shutdown_mutex);
 	}
 
+	complete(&ftgt_dev->done);
 	TRACE_EXIT();
 	return 0;
 }
@@ -610,6 +612,7 @@ static int fileio_attach_tgt(struct scst
 	init_waitqueue_head(&ftgt_dev->fdev_waitQ);
 	atomic_set(&ftgt_dev->threads_count, 0);
 	init_MUTEX_LOCKED(&ftgt_dev->shutdown_mutex);
+	init_completion(&ftgt_dev->done);
 
 	ftgt_dev->fd = fileio_open(virt_dev);
 	if (IS_ERR(ftgt_dev->fd)) {
@@ -668,6 +671,9 @@ static void fileio_detach_tgt(struct scs
 	wake_up_all(&ftgt_dev->fdev_waitQ);
 	down(&ftgt_dev->shutdown_mutex);
 
+	while (atomic_read(&ftgt_dev->threads_count))
+		wait_for_completion(&ftgt_dev->done);
+
 	filp_close(ftgt_dev->fd, NULL);
 
 	if (ftgt_dev->iv != NULL) {
@@ -3007,17 +3013,6 @@ static void __exit exit_scst_fileio_driv
 {
 	exit_scst_fileio(&disk_devtype_fileio, &disk_fileio_dev_list);
 	exit_scst_fileio(&cdrom_devtype_fileio, &cdrom_fileio_dev_list);
-
-	/* 
-	 * Wait for one sec. to allow the thread(s) actually exit,
-	 * otherwise we can get Oops. Any better way?
-	 */
-	{
-		unsigned long t = jiffies;
-		TRACE_DBG("%s", "Waiting 1 sec...");
-		while ((jiffies - t) < HZ)
-			schedule();
-	}
 }
 
 module_init(init_scst_fileio_driver);