* [PATCH] ethtool: fix inverted memchr_inv condition in ethnl_bitmap32_not_zero()
@ 2026-05-08 8:02 Chenguang Zhao
2026-05-08 9:13 ` Breno Leitao
0 siblings, 1 reply; 2+ messages in thread
From: Chenguang Zhao @ 2026-05-08 8:02 UTC (permalink / raw)
To: Andrew Lunn, Jakub Kicinski, David S. Miller, Eric Dumazet,
Paolo Abeni
Cc: Chenguang Zhao, Simon Horman, Maxime Chevallier, netdev
memchr_inv() returns non-NULL when a byte differs from the given value.
Return true in that case, not when the scanned words are all zero.
Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
---
net/ethtool/bitset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
index 8bb98d3ea3db..56b0c4867ed2 100644
--- a/net/ethtool/bitset.c
+++ b/net/ethtool/bitset.c
@@ -105,7 +105,7 @@ static bool ethnl_bitmap32_not_zero(const u32 *map, unsigned int start,
start_word++;
}
- if (!memchr_inv(map + start_word, '\0',
+ if (memchr_inv(map + start_word, '\0',
(end_word - start_word) * sizeof(u32)))
return true;
if (end % 32 == 0)
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ethtool: fix inverted memchr_inv condition in ethnl_bitmap32_not_zero()
2026-05-08 8:02 [PATCH] ethtool: fix inverted memchr_inv condition in ethnl_bitmap32_not_zero() Chenguang Zhao
@ 2026-05-08 9:13 ` Breno Leitao
0 siblings, 0 replies; 2+ messages in thread
From: Breno Leitao @ 2026-05-08 9:13 UTC (permalink / raw)
To: Chenguang Zhao
Cc: Andrew Lunn, Jakub Kicinski, David S. Miller, Eric Dumazet,
Paolo Abeni, Simon Horman, Maxime Chevallier, netdev
On Fri, May 08, 2026 at 04:02:11PM +0800, Chenguang Zhao wrote:
> memchr_inv() returns non-NULL when a byte differs from the given value.
> Return true in that case, not when the scanned words are all zero.
>
> Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn>
There is no Fixes: tag. It seems the buggy check was introduced in
commit 10b518d4e6dd ("ethtool: netlink bitset handling").
> ---
> net/ethtool/bitset.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ethtool/bitset.c b/net/ethtool/bitset.c
> index 8bb98d3ea3db..56b0c4867ed2 100644
> --- a/net/ethtool/bitset.c
> +++ b/net/ethtool/bitset.c
> @@ -105,7 +105,7 @@ static bool ethnl_bitmap32_not_zero(const u32 *map, unsigned int start,
> start_word++;
> }
>
> - if (!memchr_inv(map + start_word, '\0',
> + if (memchr_inv(map + start_word, '\0',
> (end_word - start_word) * sizeof(u32)))
> return true;
> if (end % 32 == 0)
The fix itself looks correct, but is the rest of
ethnl_bitmap32_not_zero() consistent with the documented "true if there
is a non-zero bit in [start, end)" semantics?
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-05-08 8:02 [PATCH] ethtool: fix inverted memchr_inv condition in ethnl_bitmap32_not_zero() Chenguang Zhao
2026-05-08 9:13 ` Breno Leitao
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