From: Jason Xing <kernelxing@tencent.com>

When reading wmem[0], it could be changed concurrently without
READ_ONCE() protection. So add one annotation here.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/ipv4/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c5b83875411a..e3904c006e63 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -975,7 +975,7 @@ int tcp_wmem_schedule(struct sock *sk, int copy)
 	 * Use whatever is left in sk->sk_forward_alloc and tcp_wmem[0]
 	 * to guarantee some progress.
 	 */
-	left = sock_net(sk)->ipv4.sysctl_tcp_wmem[0] - sk->sk_wmem_queued;
+	left = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]) - sk->sk_wmem_queued;
 	if (left > 0)
 		sk_forced_mem_schedule(sk, min(left, copy));
 	return min(copy, sk->sk_forward_alloc);
-- 
2.37.3

On Fri, Mar 8, 2024 at 12:25 PM Jason Xing <kerneljasonxing@gmail.com> wrote:
>
> From: Jason Xing <kernelxing@tencent.com>
>
> When reading wmem[0], it could be changed concurrently without
> READ_ONCE() protection. So add one annotation here.
>
> Signed-off-by: Jason Xing <kernelxing@tencent.com>
> ---
>  net/ipv4/tcp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index c5b83875411a..e3904c006e63 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -975,7 +975,7 @@ int tcp_wmem_schedule(struct sock *sk, int copy)
>          * Use whatever is left in sk->sk_forward_alloc and tcp_wmem[0]
>          * to guarantee some progress.
>          */
> -       left = sock_net(sk)->ipv4.sysctl_tcp_wmem[0] - sk->sk_wmem_queued;
> +       left = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]) - sk->sk_wmem_queued;

SGTM, you could have split the long line...

Reviewed-by: Eric Dumazet <edumazet@google.com>

Hi Jason,

Thank you for your modifications, that's great!

Our CI (Cirrus) did some validations with a debug kernel and here is its report:

- KVM Validation: debug (except selftest_mptcp_join):
  - Success! ✅:
  - Task: https://cirrus-ci.com/task/5015312026828800
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5015312026828800/summary/summary.txt

- KVM Validation: debug (only selftest_mptcp_join):
  - Unstable: 1 failed test(s): selftest_mptcp_join 🔴:
  - Task: https://cirrus-ci.com/task/6141211933671424
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/6141211933671424/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/e55bd7ed14f5


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-debug

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)

Hi Jason,

Thank you for your modifications, that's great!

Our CI (GitHub Action) did some validations and here is its report:

- KVM Validation: normal: Success! ✅
- KVM Validation: btf (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/8202785775

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/e55bd7ed14f5


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)