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SUNRPC: Fix up task signalling

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The RPC_TASK_KILLED flag should really not be set from another context
because it can clobber data in the struct task when task->tk_flags is
changed non-atomically.
Let's therefore swap out RPC_TASK_KILLED with an atomic flag, and add
a function to set that flag and safely wake up the task.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust
2019-04-07 13:58:44 -04:00
committed by Anna Schumaker
parent 085b775580
commit ae67bd3821
7 changed files with 40 additions and 26 deletions
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28
net/sunrpc/sched.c
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@@ -759,8 +759,7 @@ static void
rpc_reset_task_statistics(struct rpc_task *task)
{
task->tk_timeouts = 0;
task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_KILLED|RPC_TASK_SENT);
task->tk_flags &= ~(RPC_CALL_MAJORSEEN|RPC_TASK_SENT);
rpc_init_task_statistics(task);
}
@@ -773,7 +772,6 @@ void rpc_exit_task(struct rpc_task *task)
if (task->tk_ops->rpc_call_done != NULL) {
task->tk_ops->rpc_call_done(task, task->tk_calldata);
if (task->tk_action != NULL) {
WARN_ON(RPC_ASSASSINATED(task));
/* Always release the RPC slot and buffer memory */
xprt_release(task);
rpc_reset_task_statistics(task);
@@ -781,6 +779,19 @@ void rpc_exit_task(struct rpc_task *task)
}
}
void rpc_signal_task(struct rpc_task *task)
{
struct rpc_wait_queue *queue;
if (!RPC_IS_ACTIVATED(task))
return;
set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
smp_mb__after_atomic();
queue = READ_ONCE(task->tk_waitqueue);
if (queue)
rpc_wake_up_queued_task_set_status(queue, task, -ERESTARTSYS);
}
void rpc_exit(struct rpc_task *task, int status)
{
task->tk_status = status;
@@ -836,6 +847,13 @@ static void __rpc_execute(struct rpc_task *task)
*/
if (!RPC_IS_QUEUED(task))
continue;
/*
* Signalled tasks should exit rather than sleep.
*/
if (RPC_SIGNALLED(task))
rpc_exit(task, -ERESTARTSYS);
/*
* The queue->lock protects against races with
* rpc_make_runnable().
@@ -861,7 +879,7 @@ static void __rpc_execute(struct rpc_task *task)
status = out_of_line_wait_on_bit(&task->tk_runstate,
RPC_TASK_QUEUED, rpc_wait_bit_killable,
TASK_KILLABLE);
if (status == -ERESTARTSYS) {
if (status < 0) {
/*
* When a sync task receives a signal, it exits with
* -ERESTARTSYS. In order to catch any callbacks that
@@ -869,7 +887,7 @@ static void __rpc_execute(struct rpc_task *task)
* break the loop here, but go around once more.
*/
dprintk("RPC: %5u got signal\n", task->tk_pid);
task->tk_flags |= RPC_TASK_KILLED;
set_bit(RPC_TASK_SIGNALLED, &task->tk_runstate);
rpc_exit(task, -ERESTARTSYS);
}
dprintk("RPC: %5u sync task resuming\n", task->tk_pid);