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| author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2011-07-07 01:58:23 +0200 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2011-07-08 02:45:37 +0200 |
| commit | b55c59892e1f3b6c7d4b9ccffb4263e1486fb990 (patch) | |
| tree | 1fbcb0cd1febf70dc6ae6ded0e3b98ae738c1ef8 /net/sunrpc/sched.c | |
| parent | pnfs: write: Set mds_offset in the generic layer - it is needed by all LDs (diff) | |
| download | linux-b55c59892e1f3b6c7d4b9ccffb4263e1486fb990.tar.xz linux-b55c59892e1f3b6c7d4b9ccffb4263e1486fb990.zip | |
SUNRPC: Fix a race between work-queue and rpc_killall_tasks
Since rpc_killall_tasks may modify the rpc_task's tk_action field
without any locking, we need to be careful when dereferencing it.
Reported-by: Ben Greear <greearb@candelatech.com>
Tested-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@kernel.org
Diffstat (limited to 'net/sunrpc/sched.c')
| -rw-r--r-- | net/sunrpc/sched.c | 27 |
1 files changed, 11 insertions, 16 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index a27406b1654f..4814e246a874 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -616,30 +616,25 @@ static void __rpc_execute(struct rpc_task *task) BUG_ON(RPC_IS_QUEUED(task)); for (;;) { + void (*do_action)(struct rpc_task *); /* - * Execute any pending callback. + * Execute any pending callback first. */ - if (task->tk_callback) { - void (*save_callback)(struct rpc_task *); - - /* - * We set tk_callback to NULL before calling it, - * in case it sets the tk_callback field itself: - */ - save_callback = task->tk_callback; - task->tk_callback = NULL; - save_callback(task); - } else { + do_action = task->tk_callback; + task->tk_callback = NULL; + if (do_action == NULL) { /* * Perform the next FSM step. - * tk_action may be NULL when the task has been killed - * by someone else. + * tk_action may be NULL if the task has been killed. + * In particular, note that rpc_killall_tasks may + * do this at any time, so beware when dereferencing. */ - if (task->tk_action == NULL) + do_action = task->tk_action; + if (do_action == NULL) break; - task->tk_action(task); } + do_action(task); /* * Lockless check for whether task is sleeping or not. |