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greybus: fix a timeout race 

Whenever we send a request message we start a timer to ensure the
we don't wait too long for the matching response to arrive.
Currently we set up the timeout *after* sending the message, but
that is subject to a race--the response could arrive (and the
timeout prematurely disabled) before the timeout is even set up.

Set up the timeout before sending the message.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
This commit is contained in:
Alex Elder 2014-11-20 15:37:06 -06:00 committed by Greg Kroah-Hartman
parent 5e68995784
commit e8b48d1586
1 changed files with 10 additions and 3 deletions
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13
drivers/staging/greybus/operation.c
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@ -447,13 +447,20 @@ int gb_operation_request_send(struct gb_operation *operation,
*/
operation->callback = callback;
gb_pending_operation_insert(operation);
/*
* We impose a time limit for requests to complete. We need
* to set the timer before we send the request though, so we
* don't lose a race with the receipt of the resposne.
*/
timeout = msecs_to_jiffies(OPERATION_TIMEOUT_DEFAULT);
schedule_delayed_work(&operation->timeout_work, timeout);
/* All set, send the request */
ret = gb_message_send(&operation->request, GFP_KERNEL);
if (ret)
return ret;
/* We impose a time limit for requests to complete. */
timeout = msecs_to_jiffies(OPERATION_TIMEOUT_DEFAULT);
schedule_delayed_work(&operation->timeout_work, timeout);
if (!callback)
ret = gb_operation_wait(operation);