Commit c65e726a authored by Ben Walker's avatar Ben Walker Committed by Daniel Verkamp
Browse files

nvme: Limit max completions in a single poll 



For a single poll of the completion queue, if the user
submits I/O from within their completion callback and their
completion callback is particularly slow to execute, the loop
could potentially continue forever. To support this, we
need to limit the number of completions we'll process
in one batch.

Change-Id: If6bae47e52b36347dbe5622ace68c866ee88a0b2
Signed-off-by: default avatarBen Walker <benjamin.walker@intel.com>
parent 20c19967

lib/nvme/nvme_qpair.c

+6 −5
Original line number Diff line number Diff line
@@ -454,13 +454,14 @@ spdk_nvme_qpair_process_completions(struct spdk_nvme_qpair *qpair, uint32_t max_ 
		return 0;

	}



	if (max_completions == 0) {

	if (max_completions == 0 || (max_completions > (qpair->num_entries - 1U))) {



		/*

		 * max_completions == 0 means unlimited; set it to the max uint32_t value

		 *  to avoid a special case in the loop.  The maximum possible queue size is

		 *  only 64K, so num_completions will never reach this value.

		 * max_completions == 0 means unlimited, but complete at most one

		 * queue depth batch of I/O at a time so that the completion

		 * queue doorbells don't wrap around.

		 */

		max_completions = UINT32_MAX;

		max_completions = qpair->num_entries - 1;

	}



	while (1) {