[PATCH 6.1 072/197] mptcp: drop the push_pending field

Greg Kroah-Hartman
2024-02-20T21:03:13Z

From: Paolo Abeni <pabeni@redhat.com>

commit bdd70eb68913c960acb895b00a8c62eb64715b1f upstream.

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: e9d09baca676 ("mptcp: avoid atomic bit manipulation when possible")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/mptcp/protocol.c | 12 ++++++------
net/mptcp/protocol.h | 1 -
2 files changed, 6 insertions(+), 7 deletions(-)

--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1582,8 +1582,11 @@ static void mptcp_update_post_push(struc

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);
+ }
}

void __mptcp_push_pending(struct sock *sk, unsigned int flags)
@@ -3140,7 +3143,6 @@ static int mptcp_disconnect(struct sock
msk->last_snd = NULL;
WRITE_ONCE(msk->flags, 0);
msk->cb_flags = 0;
- msk->push_pending = 0;
msk->recovery = false;
msk->can_ack = false;
msk->fully_established = false;
@@ -3384,8 +3386,7 @@ static void mptcp_release_cb(struct sock
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)
@@ -3401,7 +3402,6 @@ static void mptcp_release_cb(struct sock
* 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);

--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -272,7 +272,6 @@ 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;