Commit 943806ef authored by Jim Harris's avatar Jim Harris
Browse files

init: rewrite subsystem_sort 



Commit aaba5d introduced a build warning with some
compilers. While fixing it, I realized the function was
difficult to immediately understand. So in addition to fixing
the build warning, I also made the following changes:

* Improved names for local variables
* Use TAILQ_INIT for local TAILQ instead of TAILQ_HEAD_INITIALIZER.
* Add comments explaining more clearly what the nested loops are
  doing.
* Use TAILQ_SWAP instead of a FOREACH + REMOVE + INSERT.

Fixes: aaba5d ("subsystem: Gather list changed conditions.")
Fixes issue #2978.

Signed-off-by: default avatarJim Harris <james.r.harris@intel.com>
Change-Id: Ic8740b5706537938d62a0acfac62625b2424b85f
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/17496


Reviewed-by: default avatarBen Walker <benjamin.walker@intel.com>
Reviewed-by: default avatarMike Gerdts <mgerdts@nvidia.com>
Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: default avatarShuhei Matsumoto <smatsumoto@nvidia.com>
parent de2609a2

lib/init/subsystem.c

+26 −16
Original line number Diff line number Diff line
@@ -91,37 +91,47 @@ subsystem_get_next_depend(struct spdk_subsystem_depend *cur_depend) 
static void

subsystem_sort(void)

{

	bool depends_on, depends_on_sorted;

	bool has_dependency, all_dependencies_met;

	struct spdk_subsystem *subsystem, *subsystem_tmp;

	struct spdk_subsystem_depend *subsystem_dep;



	struct spdk_subsystem_list subsystems_list = TAILQ_HEAD_INITIALIZER(subsystems_list);



	struct spdk_subsystem_list sorted_list;



	TAILQ_INIT(&sorted_list);

	/* We will move subsystems from the original g_subsystems TAILQ to the temporary

	 * sorted_list one at a time. We can only move a subsystem if it either (a) has no

	 * dependencies, or (b) all of its dependencies have already been moved to the

	 * sorted_list.

	 *

	 * Once all of the subsystems have been moved to the temporary list, we will move

	 * the list as-is back to the original g_subsystems TAILQ - they will now be sorted

	 * in the order which they must be initialized.

	 */

	while (!TAILQ_EMPTY(&g_subsystems)) {

		TAILQ_FOREACH_SAFE(subsystem, &g_subsystems, tailq, subsystem_tmp) {

			depends_on = false;

			has_dependency = false;

			all_dependencies_met = true;

			TAILQ_FOREACH(subsystem_dep, &g_subsystems_deps, tailq) {

				if (strcmp(subsystem->name, subsystem_dep->name) == 0) {

					depends_on = true;

					depends_on_sorted = !!_subsystem_find(&subsystems_list, subsystem_dep->depends_on);

					if (depends_on_sorted) {

						continue;

					}

					has_dependency = true;

					if (!_subsystem_find(&sorted_list, subsystem_dep->depends_on)) {

						/* We found a dependency that isn't in the sorted_list yet.

						 * Clear the flag and break from the inner loop, we know

						 * we can't move this subsystem to the sorted_list yet.

						 */

						all_dependencies_met = false;

						break;

					}

				}

			}



			if (!depends_on || depends_on_sorted) {

			if (!has_dependency || all_dependencies_met) {

				TAILQ_REMOVE(&g_subsystems, subsystem, tailq);

				TAILQ_INSERT_TAIL(&subsystems_list, subsystem, tailq);

				TAILQ_INSERT_TAIL(&sorted_list, subsystem, tailq);

			}

		}

	}



	TAILQ_FOREACH_SAFE(subsystem, &subsystems_list, tailq, subsystem_tmp) {

		TAILQ_REMOVE(&subsystems_list, subsystem, tailq);

		TAILQ_INSERT_TAIL(&g_subsystems, subsystem, tailq);

	}

	TAILQ_SWAP(&sorted_list, &g_subsystems, spdk_subsystem, tailq);

}



void