| Message ID | 1614243581-50870-1-git-send-email-yang.lee@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | direct-io: Using kmem_cache_zalloc() instead of kmem_cache_alloc() and memset() | expand |
Y, Yang, Yang Li <yang.lee@linux.alibaba.com> writes: > Fix the following coccicheck warning: > ./fs/direct-io.c:1155:7-23: WARNING: kmem_cache_zalloc should be used > for dio, instead of kmem_cache_alloc/memset > > Reported-by: Abaci Robot <abaci@linux.alibaba.com> > Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> > --- > fs/direct-io.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index 0957e1b..6ec2935 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -1152,7 +1152,7 @@ static inline int drop_refcount(struct dio *dio) > if (iov_iter_rw(iter) == READ && !count) > return 0; > > - dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); > + dio = kmem_cache_zalloc(dio_cache, GFP_KERNEL); > if (!dio) > return -ENOMEM; > /* > @@ -1160,8 +1160,6 @@ static inline int drop_refcount(struct dio *dio) > * performance regression in a database benchmark. So, we take > * care to only zero out what's needed. > */ > - memset(dio, 0, offsetof(struct dio, pages)); > - You must have missed the comment just above this memset: /* * Believe it or not, zeroing out the page array caused a .5% * performance regression in a database benchmark. So, we take * care to only zero out what's needed. */ That's referring to this part of the dio struct: /* * pages[] (and any fields placed after it) are not zeroed out at * allocation time. Don't add new fields after pages[] unless you * wish that they not be zeroed. */ union { struct page *pages[DIO_PAGES]; /* page buffer */ struct work_struct complete_work;/* deferred AIO completion */ }; } ____cacheline_aligned_in_smp; Nacked-by: Jeff Moyer <jmoyer@redhat.com>
diff --git a/fs/direct-io.c b/fs/direct-io.c index 0957e1b..6ec2935 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -1152,7 +1152,7 @@ static inline int drop_refcount(struct dio *dio) if (iov_iter_rw(iter) == READ && !count) return 0; - dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); + dio = kmem_cache_zalloc(dio_cache, GFP_KERNEL); if (!dio) return -ENOMEM; /* @@ -1160,8 +1160,6 @@ static inline int drop_refcount(struct dio *dio) * performance regression in a database benchmark. So, we take * care to only zero out what's needed. */ - memset(dio, 0, offsetof(struct dio, pages)); - dio->flags = flags; if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) { /* will be released by direct_io_worker */
Fix the following coccicheck warning: ./fs/direct-io.c:1155:7-23: WARNING: kmem_cache_zalloc should be used for dio, instead of kmem_cache_alloc/memset Reported-by: Abaci Robot <abaci@linux.alibaba.com> Signed-off-by: Yang Li <yang.lee@linux.alibaba.com> --- fs/direct-io.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)