diff options
| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2013-01-04 12:23:21 -0500 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2013-01-16 01:13:19 +0000 |
| commit | c45475d04b2fc3edb8a3197ac78987afb2ca42e5 (patch) | |
| tree | bb06ca7d482200f51ba165ca20f125a08e91bd9e | |
| parent | 66ebe467a6dbbd0b3917ef6ad1bd4930f9b8185d (diff) | |
SUNRPC: Ensure that we free the rpc_task after cleanups are done
commit c6567ed1402c55e19b012e66a8398baec2a726f3 upstream.
This patch ensures that we free the rpc_task after the cleanup callbacks
are done in order to avoid a deadlock problem that can be triggered if
the callback needs to wait for another workqueue item to complete.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Weston Andros Adamson <dros@netapp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | net/sunrpc/sched.c | 27 |
1 files changed, 23 insertions, 4 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index c90b83252ec..56c3f855f4e 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -880,16 +880,35 @@ struct rpc_task *rpc_new_task(const struct rpc_task_setup *setup_data) return task; } +/* + * rpc_free_task - release rpc task and perform cleanups + * + * Note that we free up the rpc_task _after_ rpc_release_calldata() + * in order to work around a workqueue dependency issue. + * + * Tejun Heo states: + * "Workqueue currently considers two work items to be the same if they're + * on the same address and won't execute them concurrently - ie. it + * makes a work item which is queued again while being executed wait + * for the previous execution to complete. + * + * If a work function frees the work item, and then waits for an event + * which should be performed by another work item and *that* work item + * recycles the freed work item, it can create a false dependency loop. + * There really is no reliable way to detect this short of verifying + * every memory free." + * + */ static void rpc_free_task(struct rpc_task *task) { - const struct rpc_call_ops *tk_ops = task->tk_ops; - void *calldata = task->tk_calldata; + unsigned short tk_flags = task->tk_flags; + + rpc_release_calldata(task->tk_ops, task->tk_calldata); - if (task->tk_flags & RPC_TASK_DYNAMIC) { + if (tk_flags & RPC_TASK_DYNAMIC) { dprintk("RPC: %5u freeing task\n", task->tk_pid); mempool_free(task, rpc_task_mempool); } - rpc_release_calldata(tk_ops, calldata); } static void rpc_async_release(struct work_struct *work) |