nvme: allow for deletion of I/O qpairs during their completion context

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ibc6566e9248cd7004aa5d4374f32b519062ed6d9

lib/nvme/nvme_ctrlr.c

@@ -205,6 +205,17 @@ spdk_nvme_ctrlr_free_io_qpair(struct spdk_nvme_qpair *qpair)
 
 	ctrlr = qpair->ctrlr;
 
+	if (qpair->in_completion_context) {
+		/*
+		 * There are many cases where it is convenient to delete an io qpair in the context
+		 *  of that qpair's completion routine.  To handle this properly, set a flag here
+		 *  so that the completion routine will perform an actual delete after the context
+		 *  unwinds.
+		 */
+		qpair->delete_after_completion_context = 1;
+		return 0;
+	}
+
 	nvme_robust_mutex_lock(&ctrlr->ctrlr_lock);
 
 	nvme_ctrlr_proc_remove_io_qpair(qpair);
@@ -947,6 +958,12 @@ nvme_ctrlr_cleanup_process(struct spdk_nvme_ctrlr_process *proc)
 	TAILQ_FOREACH_SAFE(qpair, &proc->allocated_io_qpairs, per_process_tailq, tmp_qpair) {
 		TAILQ_REMOVE(&proc->allocated_io_qpairs, qpair, per_process_tailq);
 
+		/*
+		 * The process may have been killed while some qpairs were in their
+		 *  completion context.  Clear that flag here to allow these IO
+		 *  qpairs to be deleted.
+		 */
+		qpair->in_completion_context = 0;
 		spdk_nvme_ctrlr_free_io_qpair(qpair);
 	}
 

lib/nvme/nvme_internal.h

@@ -250,6 +250,14 @@ struct spdk_nvme_qpair {
 
 	uint8_t				qprio;
 
+	/*
+	 * Members for handling IO qpair deletion inside of a completion context.
+	 * These are specifically defined as single bits, so that they do not
+	 *  push this data structure out to another cacheline.
+	 */
+	uint8_t				in_completion_context : 1;
+	uint8_t				delete_after_completion_context: 1;
+
 	struct spdk_nvme_ctrlr		*ctrlr;
 
 	/* List entry for spdk_nvme_ctrlr::active_io_qpairs */

lib/nvme/nvme_qpair.c

@@ -338,12 +338,24 @@ nvme_qpair_manual_complete_request(struct spdk_nvme_qpair *qpair,
 int32_t
 spdk_nvme_qpair_process_completions(struct spdk_nvme_qpair *qpair, uint32_t max_completions)
 {
+	int32_t ret;
+
 	if (qpair->ctrlr->is_failed) {
 		nvme_qpair_fail(qpair);
 		return 0;
 	}
 
-	return nvme_transport_qpair_process_completions(qpair, max_completions);
+	qpair->in_completion_context = 1;
+	ret = nvme_transport_qpair_process_completions(qpair, max_completions);
+	qpair->in_completion_context = 0;
+	if (qpair->delete_after_completion_context) {
+		/*
+		 * A request to delete this qpair was made in the context of this completion
+		 *  routine - so it is safe to delete it now.
+		 */
+		spdk_nvme_ctrlr_free_io_qpair(qpair);
+	}
+	return ret;
 }
 
 int
@@ -354,6 +366,9 @@ nvme_qpair_init(struct spdk_nvme_qpair *qpair, uint16_t id,
 	qpair->id = id;
 	qpair->qprio = qprio;
 
+	qpair->in_completion_context = 0;
+	qpair->delete_after_completion_context = 0;
+
 	qpair->ctrlr = ctrlr;
 	qpair->trtype = ctrlr->trid.trtype;
 

test/lib/nvme/unit/nvme_qpair_c/nvme_qpair_ut.c

@@ -142,6 +142,12 @@ nvme_transport_qpair_process_completions(struct spdk_nvme_qpair *qpair, uint32_t
 	return 0;
 }
 
+int
+spdk_nvme_ctrlr_free_io_qpair(struct spdk_nvme_qpair *qpair)
+{
+	return 0;
+}
+
 static void
 prepare_submit_request_test(struct spdk_nvme_qpair *qpair,
 			    struct spdk_nvme_ctrlr *ctrlr)