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init: rewrite subsystem_sort

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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: Jim Harris <james.r.harris@intel.com>
Change-Id: Ic8740b5706537938d62a0acfac62625b2424b85f
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/17496
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Mike Gerdts <mgerdts@nvidia.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Shuhei Matsumoto <smatsumoto@nvidia.com>
This commit is contained in:
Jim Harris 2023-04-11 12:16:55 -07:00 committed by David Ko
parent 30d24bae73
commit 9c10093483
1 changed files with 25 additions and 15 deletions
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40
lib/init/subsystem.c
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@ -91,37 +91,47 @@ subsystem_get_next_depend(struct spdk_subsystem_depend *cur_depend)
static void static void
subsystem_sort(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 *subsystem, *subsystem_tmp;
struct spdk_subsystem_depend *subsystem_dep; struct spdk_subsystem_depend *subsystem_dep;
struct spdk_subsystem_list sorted_list;
struct spdk_subsystem_list subsystems_list = TAILQ_HEAD_INITIALIZER(subsystems_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)) { while (!TAILQ_EMPTY(&g_subsystems)) {
TAILQ_FOREACH_SAFE(subsystem, &g_subsystems, tailq, subsystem_tmp) { 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) { TAILQ_FOREACH(subsystem_dep, &g_subsystems_deps, tailq) {
if (strcmp(subsystem->name, subsystem_dep->name) == 0) { if (strcmp(subsystem->name, subsystem_dep->name) == 0) {
depends_on = true; has_dependency = true;
depends_on_sorted = !!_subsystem_find(&subsystems_list, subsystem_dep->depends_on); if (!_subsystem_find(&sorted_list, subsystem_dep->depends_on)) {
if (depends_on_sorted) { /* We found a dependency that isn't in the sorted_list yet.
continue; * 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;
} }
break;
} }
} }
if (!depends_on || depends_on_sorted) { if (!has_dependency || all_dependencies_met) {
TAILQ_REMOVE(&g_subsystems, subsystem, tailq); 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_SWAP(&sorted_list, &g_subsystems, spdk_subsystem, tailq);
TAILQ_REMOVE(&subsystems_list, subsystem, tailq);
TAILQ_INSERT_TAIL(&g_subsystems, subsystem, tailq);
}
} }
void void