Commit 894cbc31 authored by Alex Elder's avatar Alex Elder Committed by Greg Kroah-Hartman
Browse files

greybus: update operation result atomically 



An operation result can be set both in and out of interrupt context.
For example, a response message could be arriving at the same time a
timeout of the operation is getting processed.  We therefore need to
ensure the result is accessed atomically.

Protect updates to the errno field using the operations spinlock.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <greg@kroah.com>
parent aa3a4d12

drivers/staging/greybus/operation.c

+20 −6
Original line number Diff line number Diff line
@@ -82,18 +82,32 @@ static DEFINE_SPINLOCK(gb_operations_lock); 
 */

static bool gb_operation_result_set(struct gb_operation *operation, int result)

{

	int prev;



	/* Nobody should be setting -EBADR */

	if (WARN_ON(result == -EBADR))

		return false;



	/* Are we sending the request message? */

	if (result == -EINPROGRESS) {

		if (WARN_ON(operation->errno != -EBADR))

			return false;

	} else if (operation->errno != -EINPROGRESS) {

		return false;

		/* Yes, but verify the result has not already been set */

		spin_lock_irq(&gb_operations_lock);

		prev = operation->errno;

		if (prev == -EBADR)

			operation->errno = result;

		spin_unlock_irq(&gb_operations_lock);



		return !WARN_ON(prev != -EBADR);

	}



	/* Trying to set final status; only the first one succeeds */

	spin_lock_irq(&gb_operations_lock);

	prev = operation->errno;

	if (prev == -EINPROGRESS)

		operation->errno = result;

	spin_unlock_irq(&gb_operations_lock);



	return true;

	return prev == -EINPROGRESS;

}



int gb_operation_result(struct gb_operation *operation)