Commit bdd70eb6 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

mptcp: drop the push_pending field 



Such field is there to avoid acquiring the data lock in a few spots,
but it adds complexity to the already non trivial locking schema.

All the relevant call sites (mptcp-level re-injection, set socket
options), are slow-path, drop such field in favor of 'cb_flags', adding
the relevant locking.

This patch could be seen as an improvement, instead of a fix. But it
simplifies the next patch. The 'Fixes' tag has been added to help having
this series backported to stable.

Fixes: e9d09bac ("mptcp: avoid atomic bit manipulation when possible")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarMat Martineau <martineau@kernel.org>
Signed-off-by: default avatarMatthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bab091d5

net/mptcp/protocol.c

+6 −6
Original line number Diff line number Diff line
@@ -1505,8 +1505,11 @@ static void mptcp_update_post_push(struct mptcp_sock *msk, 


void mptcp_check_and_set_pending(struct sock *sk)

{

	if (mptcp_send_head(sk))

		mptcp_sk(sk)->push_pending |= BIT(MPTCP_PUSH_PENDING);

	if (mptcp_send_head(sk)) {

		mptcp_data_lock(sk);

		mptcp_sk(sk)->cb_flags |= BIT(MPTCP_PUSH_PENDING);

		mptcp_data_unlock(sk);

	}

}



static int __subflow_push_pending(struct sock *sk, struct sock *ssk,
@@ -3142,7 +3145,6 @@ static int mptcp_disconnect(struct sock *sk, int flags) 
	mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE);

	WRITE_ONCE(msk->flags, 0);

	msk->cb_flags = 0;

	msk->push_pending = 0;

	msk->recovery = false;

	msk->can_ack = false;

	msk->fully_established = false;
@@ -3330,8 +3332,7 @@ static void mptcp_release_cb(struct sock *sk) 
	struct mptcp_sock *msk = mptcp_sk(sk);



	for (;;) {

		unsigned long flags = (msk->cb_flags & MPTCP_FLAGS_PROCESS_CTX_NEED) |

				      msk->push_pending;

		unsigned long flags = (msk->cb_flags & MPTCP_FLAGS_PROCESS_CTX_NEED);

		struct list_head join_list;



		if (!flags)
@@ -3347,7 +3348,6 @@ static void mptcp_release_cb(struct sock *sk) 
		 *    datapath acquires the msk socket spinlock while helding

		 *    the subflow socket lock

		 */

		msk->push_pending = 0;

		msk->cb_flags &= ~flags;

		spin_unlock_bh(&sk->sk_lock.slock);

net/mptcp/protocol.h

+0 −1
Original line number Diff line number Diff line
@@ -286,7 +286,6 @@ struct mptcp_sock { 
	int		rmem_released;

	unsigned long	flags;

	unsigned long	cb_flags;

	unsigned long	push_pending;

	bool		recovery;		/* closing subflow write queue reinjected */

	bool		can_ack;

	bool		fully_established;