From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm, slub: introduce kmem_cache_debug_flags() There are few places that call kmem_cache_debug(s) (which tests if any of debug flags are enabled for a cache) immediately followed by a test for a specific flag. The compiler can probably eliminate the extra check, but we can make the code nicer by introducing kmem_cache_debug_flags() that works like kmem_cache_debug() (including the static key check) but tests for specific flag(s). The next patches will add more users. [vbabka@xxxxxxx: change return from int to bool, per Kees. Add VM_WARN_ON_ONCE() for invalid flags, per Roman] Link: http://lkml.kernel.org/r/949b90ed-e0f0-07d7-4d21-e30ec0958a7c@xxxxxxx Link: http://lkml.kernel.org/r/20200610163135.17364-8-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Acked-by: Christoph Lameter <cl@xxxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Vijayanand Jitta <vjitta@xxxxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) --- a/mm/slub.c~mm-slub-introduce-kmem_cache_debug_flags +++ a/mm/slub.c @@ -122,18 +122,29 @@ DEFINE_STATIC_KEY_FALSE(slub_debug_enabl #endif #endif -static inline int kmem_cache_debug(struct kmem_cache *s) +/* + * Returns true if any of the specified slub_debug flags is enabled for the + * cache. Use only for flags parsed by setup_slub_debug() as it also enables + * the static key. + */ +static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t flags) { + VM_WARN_ON_ONCE(!(flags & SLAB_DEBUG_FLAGS)); #ifdef CONFIG_SLUB_DEBUG if (static_branch_unlikely(&slub_debug_enabled)) - return s->flags & SLAB_DEBUG_FLAGS; + return s->flags & flags; #endif - return 0; + return false; +} + +static inline bool kmem_cache_debug(struct kmem_cache *s) +{ + return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS); } void *fixup_red_left(struct kmem_cache *s, void *p) { - if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) + if (kmem_cache_debug_flags(s, SLAB_RED_ZONE)) p += s->red_left_pad; return p; @@ -4060,7 +4071,7 @@ void __check_heap_object(const void *ptr offset = (ptr - page_address(page)) % s->size; /* Adjust for redzone and reject if within the redzone. */ - if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) { + if (kmem_cache_debug_flags(s, SLAB_RED_ZONE)) { if (offset < s->red_left_pad) usercopy_abort("SLUB object in left red zone", s->name, to_user, offset, n); _
