[PATCH v4a 01/38] SUNRPC/xprt: Use del_timer_sync() instead of del_singleshot_timer_sync()

Steven Rostedt
2022-11-05T06:03:06Z

From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

Back on June 22, 2005, it was decided to use del_singleshot_timer_sync()
because it wouldn't loop like del_timer_sync(), and since the timer that
was being removed was not about to be rearmed, it was considered an
efficiency to use del_singleshot_timer_sync() over del_timer_sync().

But on June 23, 2005, commit 55c888d6d09a0 ("timers fixes/improvements")
happened, which converted del_singleshot_timer_sync() into:

#define del_singleshot_timer_sync(t) del_timer_sync(t)

Making the to equivalent.

Now work is being done to add a "shutdown" state to timers where a timer
must be in that state in order to be freed to prevent use-after-free bugs
caused by timers being re-armed just before being freed, the
del_singleshot_timer_sync() is now being converted into something that
will set the timer to the shutdown state. This means that once
del_singleshot_timer_sync() is called, the timer can no longer be
re-armed.

As the timer here will be re-armed, it can not use del_singleshot_timer_sync().
But as the reason it was used in the first place no longer exists, just
use del_timer_sync().

Link: https://lore.kernel.org/lkml/20221028145005.28bc324d@gandalf.local.home/

Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-nfs@vger.kernel.org
Cc: netdev@vger.kernel.org
Fixes: 0f9dc2b16884b ("RPC: Clean up socket autodisconnect")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
net/sunrpc/xprt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 656cec208371..ab453ede54f0 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1164,7 +1164,7 @@ xprt_request_enqueue_receive(struct rpc_task *task)
spin_unlock(&xprt->queue_lock);

/* Turn off autodisconnect */
- del_singleshot_timer_sync(&xprt->timer);
+ del_timer_sync(&xprt->timer);
return 0;
}

--
2.35.1