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[PATCH mptcp-net 3/3] mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags

Mat Martineau posted 3 patches 3 years, 2 months ago
Maintainers: Mat Martineau <mathew.j.martineau@linux.intel.com>, Jakub Kicinski <kuba@kernel.org>, Eric Dumazet <edumazet@google.com>, "David S. Miller" <davem@davemloft.net>, Geliang Tang <geliangtang@gmail.com>, Matthieu Baerts <matthieu.baerts@tessares.net>, Paolo Abeni <pabeni@redhat.com>
There is a newer version of this series
[PATCH mptcp-net 3/3] mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags
Posted by Mat Martineau 3 years, 2 months ago 
When setting up a subflow's flags for sending MP_PRIO MPTCP options, the
subflow socket lock was not held while reading and modifying several
struct members that are also read and modified in mptcp_write_options().

Acquire the subflow socket lock earlier and send the MP_PRIO ACK with
that lock already acquired.

Fixes: 067065422fcd ("mptcp: add the outgoing MP_PRIO support")
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
 net/mptcp/pm_netlink.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index d04b34fc9a8e..05c6a95e9c28 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -729,11 +729,13 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 		struct sock *sk = (struct sock *)msk;
 		struct mptcp_addr_info local;
+		bool slow;
 
 		local_address((struct sock_common *)ssk, &local);
 		if (!mptcp_addresses_equal(&local, addr, addr->port))
 			continue;
 
+		slow = lock_sock_fast(ssk);
 		if (subflow->backup != bkup)
 			msk->last_snd = NULL;
 		subflow->backup = bkup;
@@ -742,7 +744,8 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
 		__MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIOTX);
 
 		pr_debug("send ack for mp_prio");
-		mptcp_subflow_send_ack(ssk);
+		__mptcp_subflow_send_ack(ssk);
+		unlock_sock_fast(ssk, slow);
 
 		return 0;
 	}
-- 
2.37.0
Re: [PATCH mptcp-net 3/3] mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags
Posted by Paolo Abeni 3 years, 2 months ago 
On Tue, 2022-06-28 at 12:03 -0700, Mat Martineau wrote:
> When setting up a subflow's flags for sending MP_PRIO MPTCP options, the
> subflow socket lock was not held while reading and modifying several
> struct members that are also read and modified in mptcp_write_options().
> 
> Acquire the subflow socket lock earlier and send the MP_PRIO ACK with
> that lock already acquired.
> 
> Fixes: 067065422fcd ("mptcp: add the outgoing MP_PRIO support")
> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
> ---
>  net/mptcp/pm_netlink.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index d04b34fc9a8e..05c6a95e9c28 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -729,11 +729,13 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
>  		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
>  		struct sock *sk = (struct sock *)msk;
>  		struct mptcp_addr_info local;
> +		bool slow;
>  
>  		local_address((struct sock_common *)ssk, &local);
>  		if (!mptcp_addresses_equal(&local, addr, addr->port))
>  			continue;
>  
> +		slow = lock_sock_fast(ssk);
>  		if (subflow->backup != bkup)
>  			msk->last_snd = NULL;
>  		subflow->backup = bkup;
> @@ -742,7 +744,8 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
>  		__MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIOTX);
>  
>  		pr_debug("send ack for mp_prio");
> -		mptcp_subflow_send_ack(ssk);
> +		__mptcp_subflow_send_ack(ssk);
> +		unlock_sock_fast(ssk, slow);

After this chunk, we can remove mptcp_subflow_send_ack() from
protocol.h and make it static. I think it's easier squashing this patch
into the previous one.

Thanks!

Paolo
>  
>  		return 0;
>  	}
Re: [PATCH mptcp-net 3/3] mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags
Posted by Mat Martineau 3 years, 2 months ago 
On Wed, 29 Jun 2022, Paolo Abeni wrote:

> On Tue, 2022-06-28 at 12:03 -0700, Mat Martineau wrote:
>> When setting up a subflow's flags for sending MP_PRIO MPTCP options, the
>> subflow socket lock was not held while reading and modifying several
>> struct members that are also read and modified in mptcp_write_options().
>>
>> Acquire the subflow socket lock earlier and send the MP_PRIO ACK with
>> that lock already acquired.
>>
>> Fixes: 067065422fcd ("mptcp: add the outgoing MP_PRIO support")
>> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
>> ---
>>  net/mptcp/pm_netlink.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
>> index d04b34fc9a8e..05c6a95e9c28 100644
>> --- a/net/mptcp/pm_netlink.c
>> +++ b/net/mptcp/pm_netlink.c
>> @@ -729,11 +729,13 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
>>  		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
>>  		struct sock *sk = (struct sock *)msk;
>>  		struct mptcp_addr_info local;
>> +		bool slow;
>>
>>  		local_address((struct sock_common *)ssk, &local);
>>  		if (!mptcp_addresses_equal(&local, addr, addr->port))
>>  			continue;
>>
>> +		slow = lock_sock_fast(ssk);
>>  		if (subflow->backup != bkup)
>>  			msk->last_snd = NULL;
>>  		subflow->backup = bkup;
>> @@ -742,7 +744,8 @@ static int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk,
>>  		__MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIOTX);
>>
>>  		pr_debug("send ack for mp_prio");
>> -		mptcp_subflow_send_ack(ssk);
>> +		__mptcp_subflow_send_ack(ssk);
>> +		unlock_sock_fast(ssk, slow);
>
> After this chunk, we can remove mptcp_subflow_send_ack() from
> protocol.h and make it static. I think it's easier squashing this patch
> into the previous one.
>

There's still a call to mptcp_subflow_send_ack() in pm_netlink.c, so I'll 
leave both in protocol.h for now. Will squash patches 2 & 3 though.

--
Mat Martineau
Intel
Re: mptcp: Acquire the subflow socket lock before modifying MP_PRIO flags: Tests Results
Posted by MPTCP CI 3 years, 2 months ago 
Hi Mat,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal:
  - Unstable: 1 failed test(s): selftest_simult_flows 🔴:
  - Task: https://cirrus-ci.com/task/5828656101588992
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5828656101588992/summary/summary.txt

- KVM Validation: debug:
  - Unstable: 2 failed test(s): packetdrill_add_addr selftest_mptcp_join 🔴:
  - Task: https://cirrus-ci.com/task/5265706148167680
  - Summary: https://api.cirrus-ci.com/v1/artifact/task/5265706148167680/summary/summary.txt

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/aebc91b918e8


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 (Tessares)

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