In kmem_cache_cpu we currently have a union of the freelist+tid pair
with freelist_aba_t, relying implicitly on the type compatibility with the
freelist+counters pair used in freelist_aba_t.
To allow further changes to freelist_aba_t, we can instead define a
separate struct freelist_tid (instead of a typedef, per the coding
style) for kmem_cache_cpu, as that affects only a single helper
__update_cpu_freelist_fast().
We can add the resulting struct freelist_tid to kmem_cache_cpu as
unnamed field thanks to -fms-extensions, so that freelist and tid fields
can still be accessed directly.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/slub.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 074abe8e79f8..5f6408c9e0fd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -411,18 +411,22 @@ enum stat_item {
};
#ifndef CONFIG_SLUB_TINY
-/*
- * When changing the layout, make sure freelist and tid are still compatible
- * with this_cpu_cmpxchg_double() alignment requirements.
- */
-struct kmem_cache_cpu {
+struct freelist_tid {
union {
struct {
- void **freelist; /* Pointer to next available object */
+ void *freelist; /* Pointer to next available object */
unsigned long tid; /* Globally unique transaction id */
};
- freelist_aba_t freelist_tid;
+ freelist_full_t freelist_tid;
};
+};
+
+/*
+ * When changing the layout, make sure freelist and tid are still compatible
+ * with this_cpu_cmpxchg_double() alignment requirements.
+ */
+struct kmem_cache_cpu {
+ struct freelist_tid;
struct slab *slab; /* The slab from which we are allocating */
#ifdef CONFIG_SLUB_CPU_PARTIAL
struct slab *partial; /* Partially allocated slabs */
@@ -4367,11 +4371,11 @@ __update_cpu_freelist_fast(struct kmem_cache *s,
void *freelist_old, void *freelist_new,
unsigned long tid)
{
- freelist_aba_t old = { .freelist = freelist_old, .counter = tid };
- freelist_aba_t new = { .freelist = freelist_new, .counter = next_tid(tid) };
+ struct freelist_tid old = { .freelist = freelist_old, .tid = tid };
+ struct freelist_tid new = { .freelist = freelist_new, .tid = next_tid(tid) };
- return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid.full,
- &old.full, new.full);
+ return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid,
+ &old.freelist_tid, new.freelist_tid);
}
/*
--
2.51.1