Re: [PATCH] Revert "net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and}"

From: Michael S. Tsirkin
Date: Wed Oct 19 2022 - 08:15:52 EST


On Sun, Oct 16, 2022 at 08:09:47PM -0700, Yury Norov wrote:
> This reverts commit 854701ba4c39afae2362ba19a580c461cb183e4f.
>
> The reverted commit makes netif_attr_test_online() network subsystems
> generating warnings, and it breaks syzkaller testing.
>
> https://syzkaller.appspot.com/bug?extid=9abe5ecc348676215427
>
> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>

Fixes: 854701ba4c39 ("net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and}")
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
> include/linux/netdevice.h | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index a36edb0ec199..eddf8ee270e7 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -3663,8 +3663,9 @@ static inline bool netif_attr_test_online(unsigned long j,
> static inline unsigned int netif_attrmask_next(int n, const unsigned long *srcp,
> unsigned int nr_bits)
> {
> - /* n is a prior cpu */
> - cpu_max_bits_warn(n + 1, nr_bits);
> + /* -1 is a legal arg here. */
> + if (n != -1)
> + cpu_max_bits_warn(n, nr_bits);
>
> if (srcp)
> return find_next_bit(srcp, nr_bits, n + 1);
> @@ -3685,8 +3686,9 @@ static inline int netif_attrmask_next_and(int n, const unsigned long *src1p,
> const unsigned long *src2p,
> unsigned int nr_bits)
> {
> - /* n is a prior cpu */
> - cpu_max_bits_warn(n + 1, nr_bits);
> + /* -1 is a legal arg here. */
> + if (n != -1)
> + cpu_max_bits_warn(n, nr_bits);
>
> if (src1p && src2p)
> return find_next_and_bit(src1p, src2p, nr_bits, n + 1);
> --
> 2.34.1