[PATCH -mm][AIO] AIO completion signal notification fixes andcleanups

[Sébastien Dugué]

  Andrew, here is another incremental patch which does a bit of cleanup
as well as fixing a possible release on a task ref that was not taken.

  Thanks,

  Sébastien.


From: Sébastien Dugué <sebastien.dugue@xxxxxxxx>

	AIO completion signal notification misc fixes and cleanups

  This patches cleans up the notification path and fixes a possible
release on a task ref that was not taken in aio_setup_sigevent().


 aio.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

Signed-off-by: Sébastien Dugué <sebastien.dugue@xxxxxxxx>


Index: linux-2.6.20-rc6-mm3/fs/aio.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/fs/aio.c	2007-02-05 16:53:43.000000000 +0100
+++ linux-2.6.20-rc6-mm3/fs/aio.c	2007-02-06 09:33:55.000000000 +0100
@@ -469,8 +469,7 @@ static inline void really_put_req(struct
 		kfree(req->ki_iovec);
 
 	/* Release task ref */
-	if (req->ki_notify.notify == SIGEV_THREAD_ID ||
-	    req->ki_notify.notify == SIGEV_SIGNAL)
+	if (req->ki_notify.notify != SIGEV_NONE)
 		put_task_struct(req->ki_notify.target);
 
 	kmem_cache_free(kiocb_cachep, req);
@@ -970,8 +969,14 @@ static long aio_setup_sigevent(struct ai
 	rcu_read_lock();
 	target = sigevent_find_task(&event);
 
-	if (unlikely(!target))
+	if (unlikely(!target)) {
+		/*
+		 * Revert notify to SIGEV_NONE so that really_put_req()
+		 * knows that no ref has been taken on a task.
+		 */
+		notify->notify = SIGEV_NONE;
 		goto out_unlock;
+	}
 
 	/*
 	 * At this point, we know that notify is either SIGEV_SIGNAL or
@@ -996,7 +1001,7 @@ static long aio_setup_sigevent(struct ai
 	return 0;
 
 out_unlock:
-	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 	return -EINVAL;
 }
 
@@ -1763,7 +1768,7 @@ int fastcall io_submit_one(struct kioctx
 					 (struct sigevent __user *)(unsigned long)
 					 iocb->aio_sigeventp);
 		if (ret)
-			goto out_put_req;
+			goto out_sigqfree;
 	}
 
 	/* Attach this iocb to its lio */
-
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