[PATCH v2 2/6] mm/slub: move struct track init out of set_track()

From: Vlastimil Babka
Date: Wed Mar 02 2022 - 12:32:22 EST


set_track() either zeroes out the struct track or fills it, depending on
the addr parameter. This is unnecessary as there's only one place that
calls it for the initialization - init_tracking(). We can simply do the
zeroing there, with a single memset() that covers both TRACK_ALLOC and
TRACK_FREE as they are adjacent.

Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-and-tested-by: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
---
mm/slub.c | 32 +++++++++++++++-----------------
1 file changed, 15 insertions(+), 17 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 261474092e43..1fc451f4fe62 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -729,34 +729,32 @@ static void set_track(struct kmem_cache *s, void *object,
{
struct track *p = get_track(s, object, alloc);

- if (addr) {
#ifdef CONFIG_STACKTRACE
- unsigned int nr_entries;
+ unsigned int nr_entries;

- metadata_access_enable();
- nr_entries = stack_trace_save(kasan_reset_tag(p->addrs),
- TRACK_ADDRS_COUNT, 3);
- metadata_access_disable();
+ metadata_access_enable();
+ nr_entries = stack_trace_save(kasan_reset_tag(p->addrs),
+ TRACK_ADDRS_COUNT, 3);
+ metadata_access_disable();

- if (nr_entries < TRACK_ADDRS_COUNT)
- p->addrs[nr_entries] = 0;
+ if (nr_entries < TRACK_ADDRS_COUNT)
+ p->addrs[nr_entries] = 0;
#endif
- p->addr = addr;
- p->cpu = smp_processor_id();
- p->pid = current->pid;
- p->when = jiffies;
- } else {
- memset(p, 0, sizeof(struct track));
- }
+ p->addr = addr;
+ p->cpu = smp_processor_id();
+ p->pid = current->pid;
+ p->when = jiffies;
}

static void init_tracking(struct kmem_cache *s, void *object)
{
+ struct track *p;
+
if (!(s->flags & SLAB_STORE_USER))
return;

- set_track(s, object, TRACK_FREE, 0UL);
- set_track(s, object, TRACK_ALLOC, 0UL);
+ p = get_track(s, object, TRACK_ALLOC);
+ memset(p, 0, 2*sizeof(struct track));
}

static void print_track(const char *s, struct track *t, unsigned long pr_time)
--
2.35.1