| Message ID | 20221008020312.1932347-1-aahringo@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: slab: comment __GFP_ZERO case for kmem_cache_alloc | expand |
On Fri, Oct 07, 2022 at 10:03:12PM -0400, Alexander Aring wrote: > This patch will add a comment for the __GFP_ZERO flag case for > kmem_cache_alloc(). As the current comment mentioned that the flags only > matters if the cache has no available objects it's different for the > __GFP_ZERO flag which will ensure that the returned object is always > zeroed in any case. > > I have the feeling I run into this question already two times if the > user need to zero the object or not, but the user does not need to zero > the object afterwards. However another use of __GFP_ZERO and only zero > the object if the cache has no available objects would also make no > sense. > > Signed-off-by: Alexander Aring <aahringo@redhat.com> > --- > mm/slab.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/slab.c b/mm/slab.c > index 10e96137b44f..7a84c2aae85a 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -3482,7 +3482,8 @@ void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, > * @flags: See kmalloc(). > * > * Allocate an object from this cache. The flags are only relevant > - * if the cache has no available objects. > + * if the cache has no available objects. Except flag __GFP_ZERO which > + * will zero the returned object. > * > * Return: pointer to the new object or %NULL in case of error > */ > -- > 2.31.1 > Acked-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Thanks!
On Fri, 7 Oct 2022, Alexander Aring wrote: > diff --git a/mm/slab.c b/mm/slab.c > index 10e96137b44f..7a84c2aae85a 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -3482,7 +3482,8 @@ void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, > * @flags: See kmalloc(). > * > * Allocate an object from this cache. The flags are only relevant > - * if the cache has no available objects. > + * if the cache has no available objects. Except flag __GFP_ZERO which > + * will zero the returned object. Minor nit: it's probably better to do "... has no available objects, except flag ..." and not seperate sentences. After that is done, feel free to add Acked-by: David Rientjes <rientjes@google.com>
diff --git a/mm/slab.c b/mm/slab.c index 10e96137b44f..7a84c2aae85a 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3482,7 +3482,8 @@ void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, * @flags: See kmalloc(). * * Allocate an object from this cache. The flags are only relevant - * if the cache has no available objects. + * if the cache has no available objects. Except flag __GFP_ZERO which + * will zero the returned object. * * Return: pointer to the new object or %NULL in case of error */
This patch will add a comment for the __GFP_ZERO flag case for kmem_cache_alloc(). As the current comment mentioned that the flags only matters if the cache has no available objects it's different for the __GFP_ZERO flag which will ensure that the returned object is always zeroed in any case. I have the feeling I run into this question already two times if the user need to zero the object or not, but the user does not need to zero the object afterwards. However another use of __GFP_ZERO and only zero the object if the cache has no available objects would also make no sense. Signed-off-by: Alexander Aring <aahringo@redhat.com> --- mm/slab.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)