2022-10-17 03:26:01

by Yury Norov

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

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 <[email protected]>
---
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

2022-10-19 12:26:17

by Michael S. Tsirkin

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

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 <[email protected]>

Fixes: 854701ba4c39 ("net: fix cpu_max_bits_warn() usage in netif_attrmask_next{,_and}")
Acked-by: Michael S. Tsirkin <[email protected]>

> ---
> 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

2022-10-19 14:41:45

by Christian Borntraeger

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

for virtio on s390x.

Tested-by: Christian Borntraeger <[email protected]>