2023-12-21 09:10:58

by Dmitry Antipov

[permalink] [raw]
Subject: [PATCH] watch_queue: fix kcalloc() arguments order

When compiling with gcc version 14.0.0 20231220 (experimental)
and W=1, I've noticed the following warning:

kernel/watch_queue.c: In function 'watch_queue_set_size':
kernel/watch_queue.c:273:32: warning: 'kcalloc' sizes specified with 'sizeof'
in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
273 | pages = kcalloc(sizeof(struct page *), nr_pages, GFP_KERNEL);
| ^~~~~~

Since 'n' and 'size' arguments of 'kcalloc()' are multiplied to
calculate the final size, their actual order doesn't affect the
result and so this is not a bug. But it's still worth to fix it.

Signed-off-by: Dmitry Antipov <[email protected]>
---
kernel/watch_queue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c
index 778b4056700f..03b90d7d2175 100644
--- a/kernel/watch_queue.c
+++ b/kernel/watch_queue.c
@@ -270,7 +270,7 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes)
goto error;

ret = -ENOMEM;
- pages = kcalloc(sizeof(struct page *), nr_pages, GFP_KERNEL);
+ pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
if (!pages)
goto error;

--
2.43.0



2023-12-21 12:13:53

by Christian Brauner

[permalink] [raw]
Subject: Re: [PATCH] watch_queue: fix kcalloc() arguments order

On Thu, 21 Dec 2023 12:01:21 +0300, Dmitry Antipov wrote:
> When compiling with gcc version 14.0.0 20231220 (experimental)
> and W=1, I've noticed the following warning:
>
> kernel/watch_queue.c: In function 'watch_queue_set_size':
> kernel/watch_queue.c:273:32: warning: 'kcalloc' sizes specified with 'sizeof'
> in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
> 273 | pages = kcalloc(sizeof(struct page *), nr_pages, GFP_KERNEL);
> | ^~~~~~
>
> [...]

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.misc

[1/1] watch_queue: fix kcalloc() arguments order
https://git.kernel.org/vfs/vfs/c/770bedae3662