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| author | Zhen Lei <thunder.leizhen@huawei.com> | 2020-08-07 09:22:59 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-07 21:33:26 +0300 |
| commit | 7bba8f0ea428f8a904c022b86e584009a2f87357 (patch) | |
| tree | d39baaa8f1c88c4a2ba6bd51761a3acd693e743a /mm/mmap.c | |
| parent | 2a681cfa5bb41e78e7bfafbb748b581374ce9b1d (diff) | |
| download | linux-7bba8f0ea428f8a904c022b86e584009a2f87357.tar.xz | |
mm/mmap: optimize a branch judgment in ksys_mmap_pgoff()
Look at the pseudo code below. It's very clear that, the judgement
"!is_file_hugepages(file)" at 3) is duplicated to the one at 1), we can
use "else if" to avoid it. And the assignment "retval = -EINVAL" at 2) is
only needed by the branch 3), because "retval" will be overwritten at 4).
No functional change, but it can reduce the code size. Maybe more clearer?
Before:
text data bss dec hex filename
28733 1590 1 30324 7674 mm/mmap.o
After:
text data bss dec hex filename
28701 1590 1 30292 7654 mm/mmap.o
====pseudo code====:
if (!(flags & MAP_ANONYMOUS)) {
...
1) if (is_file_hugepages(file))
len = ALIGN(len, huge_page_size(hstate_file(file)));
2) retval = -EINVAL;
3) if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
goto out_fput;
} else if (flags & MAP_HUGETLB) {
...
}
...
4) retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
out_fput:
...
return retval;
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200705080112.1405-1-thunder.leizhen@huawei.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index dcdab2675a21..853ae3aebc3d 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1562,11 +1562,12 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, file = fget(fd); if (!file) return -EBADF; - if (is_file_hugepages(file)) + if (is_file_hugepages(file)) { len = ALIGN(len, huge_page_size(hstate_file(file))); - retval = -EINVAL; - if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) + } else if (unlikely(flags & MAP_HUGETLB)) { + retval = -EINVAL; goto out_fput; + } } else if (flags & MAP_HUGETLB) { struct user_struct *user = NULL; struct hstate *hs; |