Commit b244358e authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

slab: separate struct freelist_tid from kmem_cache_cpu 



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.

Reviewed-by: default avatarHarry Yoo <harry.yoo@oracle.com>
Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
parent c99f969d

mm/slub.c

+15 −11
Original line number Diff line number Diff line
@@ -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);

}



/*