diff options
| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-01-07 14:30:46 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-17 08:46:08 -0800 |
| commit | 5758b7dc3cc847cf0c3b3f4df9e3acb44aaffd0e (patch) | |
| tree | af7c4375854c95d5aaba8c907a683cbb4a30f074 /net/sunrpc | |
| parent | 0649c30fca0f15d0aae670b6e4cfa9e5776e6117 (diff) | |
| download | lwn-5758b7dc3cc847cf0c3b3f4df9e3acb44aaffd0e.tar.gz lwn-5758b7dc3cc847cf0c3b3f4df9e3acb44aaffd0e.zip | |
SUNRPC: Ensure we release the socket write lock if the rpc_task exits early
commit 87ed50036b866db2ec2ba16b2a7aec4a2b0b7c39 upstream.
If the rpc_task exits while holding the socket write lock before it has
allocated an rpc slot, then the usual mechanism for releasing the write
lock in xprt_release() is defeated.
The problem occurs if the call to xprt_lock_write() initially fails, so
that the rpc_task is put on the xprt->sending wait queue. If the task
exits after being assigned the lock by __xprt_lock_write_func, but
before it has retried the call to xprt_lock_and_alloc_slot(), then
it calls xprt_release() while holding the write lock, but will
immediately exit due to the test for task->tk_rqstp != NULL.
Reported-by: Chris Perl <chris.perl@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/sched.c | 3 | ||||
| -rw-r--r-- | net/sunrpc/xprt.c | 12 |
2 files changed, 11 insertions, 4 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 6dba49cf52b1..7865b44515ec 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -957,8 +957,7 @@ static void rpc_async_release(struct work_struct *work) static void rpc_release_resources_task(struct rpc_task *task) { - if (task->tk_rqstp) - xprt_release(task); + xprt_release(task); if (task->tk_msg.rpc_cred) { put_rpccred(task->tk_msg.rpc_cred); task->tk_msg.rpc_cred = NULL; diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index bd462a532acf..33811db8788a 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1136,10 +1136,18 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt) void xprt_release(struct rpc_task *task) { struct rpc_xprt *xprt; - struct rpc_rqst *req; + struct rpc_rqst *req = task->tk_rqstp; - if (!(req = task->tk_rqstp)) + if (req == NULL) { + if (task->tk_client) { + rcu_read_lock(); + xprt = rcu_dereference(task->tk_client->cl_xprt); + if (xprt->snd_task == task) + xprt_release_write(xprt, task); + rcu_read_unlock(); + } return; + } xprt = req->rq_xprt; if (task->tk_ops->rpc_count_stats != NULL) |