On Fri, 2015-07-31 at 15:04 +0530, Viresh Kumar wrote:
On 31-07-15, 17:32, yalin wang wrote:
On Jul 31, 2015, at 16:56, Kirill A. Shutemov kirill@shutemov.name wrote:
On Fri, Jul 31, 2015 at 02:08:34PM +0530, Viresh Kumar wrote:
IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag and there is no need to do that again from its callers. Drop it.
Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com
search in code, there are lots of using like this , does need add this check into checkpatch ?
cc'd Joe for that. :)
# grep -r 'likely.*IS_ERR' . ./include/linux/blk-cgroup.h: if (unlikely(IS_ERR(blkg))) ./fs/nfs/objlayout/objio_osd.c: if (unlikely(IS_ERR(od))) { ./fs/cifs/readdir.c: if (unlikely(IS_ERR(dentry))) ./fs/ext4/extents.c: if (unlikely(IS_ERR(bh))) { ./fs/ext4/extents.c: if (unlikely(IS_ERR(path1))) { ./fs/ext4/extents.c: if (unlikely(IS_ERR(path2))) {
Btw, my series has fixed all of them :)
If it's all fixed, then it's unlikely to be needed in checkpatch.
But given the unlikely was added when using gcc3.4, I wonder if it's still appropriate to use unlikely in IS_ERR at all.
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commit b5acea523151452c37cd428437e7576a291dd146 Author: Andrew Morton akpm@osdl.org Date: Sun Aug 22 23:04:49 2004 -0700
[PATCH] mark IS_ERR as unlikely()
It seems fair to assume that it is always unlikely that IS_ERR will return true.
This patch changes the gcc-3.4-generated kernel text by ~500 bytes (less) so it's fair to assume that the compiler is indeed propagating unlikeliness out of inline functions.