[PATCH -mm][AIO] AIO completion signal notification fixes and cleanups

Sébastien Dugué
2007-02-06T09:24:13Z

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@bull.net>

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@bull.net>

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 */