From: Stefano Garzarella <sgarzare@redhat.com>
To: Dexuan Cui <decui@microsoft.com>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, arseny.krasnov@kaspersky.com,
netdev@vger.kernel.org,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, kys@microsoft.com,
haiyangz@microsoft.com, stephen@networkplumber.org,
wei.liu@kernel.org, linux-hyperv@vger.kernel.org
Subject: Re: [PATCH 2/2] vsock: fix possible infinite sleep in vsock_connectible_wait_data()
Date: Mon, 31 Oct 2022 09:43:27 +0100 [thread overview]
Message-ID: <20221031084327.63vikvodhs7aowhe@sgarzare-redhat> (raw)
In-Reply-To: <20221028205646.28084-3-decui@microsoft.com>
On Fri, Oct 28, 2022 at 01:56:46PM -0700, Dexuan Cui wrote:
>Currently vsock_connectible_has_data() may miss a wakeup operation
>between vsock_connectible_has_data() == 0 and the prepare_to_wait().
>
>Fix the race by adding the process to the wait qeuue before checking
s/qeuue/queue
>vsock_connectible_has_data().
>
>Fixes: b3f7fd54881b ("af_vsock: separate wait data loop")
>Signed-off-by: Dexuan Cui <decui@microsoft.com>
>---
> net/vmw_vsock/af_vsock.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index d258fd43092e..03a6b5bc6ba7 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -1905,8 +1905,11 @@ static int vsock_connectible_wait_data(struct sock *sk,
> err = 0;
> transport = vsk->transport;
>
>- while ((data = vsock_connectible_has_data(vsk)) == 0) {
>+ while (1) {
> prepare_to_wait(sk_sleep(sk), wait, TASK_INTERRUPTIBLE);
>+ data = vsock_connectible_has_data(vsk);
>+ if (data != 0)
>+ break;
>
> if (sk->sk_err != 0 ||
> (sk->sk_shutdown & RCV_SHUTDOWN) ||
>@@ -1937,6 +1940,8 @@ static int vsock_connectible_wait_data(struct sock *sk,
> err = -EAGAIN;
> break;
> }
>+
>+ finish_wait(sk_sleep(sk), wait);
Since we are going to call again prepare_to_wait() on top of the loop,
is finish_wait() call here really needed?
What about following what we do in vsock_accept and vsock_connect?
prepare_to_wait()
while (condition) {
...
prepare_to_wait();
}
finish_wait()
I find it a little more readable, but your solution is fine too.
Thanks,
Stefano
next prev parent reply other threads:[~2022-10-31 8:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-28 20:56 [PATCH 0/2] vsock: remove an unused variable and fix infinite sleep Dexuan Cui
2022-10-28 20:56 ` [PATCH 1/2] vsock: remove the unused 'wait' in vsock_connectible_recvmsg() Dexuan Cui
2022-10-31 8:37 ` Stefano Garzarella
2022-10-28 20:56 ` [PATCH 2/2] vsock: fix possible infinite sleep in vsock_connectible_wait_data() Dexuan Cui
2022-10-31 8:43 ` Stefano Garzarella [this message]
2022-11-01 1:58 ` Dexuan Cui
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