From: David Howells Date: Wed, 4 Dec 2024 07:46:45 +0000 (+0000) Subject: rxrpc: Don't need barrier for ->tx_bottom and ->acks_hard_ack X-Git-Tag: v6.14-rc1~162^2~261^2~22 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6396b48ac0a77165f9c2c40ab03d6c8188c89739;p=thirdparty%2Fkernel%2Flinux.git rxrpc: Don't need barrier for ->tx_bottom and ->acks_hard_ack We don't need a barrier for the ->tx_bottom value (which indicates the lowest sequence still in the transmission queue) and the ->acks_hard_ack value (which tracks the DATA packets hard-ack'd by the latest ACK packet received and thus indicates which DATA packets can now be discarded) as the app thread doesn't use either value as a reference to memory to access. Rather, the app thread merely uses these as a guide to how much space is available in the transmission queue Change the code to use READ/WRITE_ONCE() instead. Also, change rxrpc_check_tx_space() to use the same value for tx_bottom throughout. Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20241204074710.990092-18-dhowells@redhat.com Signed-off-by: Jakub Kicinski --- diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index 786c1fb1369ab..467c9402882e6 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -94,9 +94,11 @@ no_wait: */ static bool rxrpc_check_tx_space(struct rxrpc_call *call, rxrpc_seq_t *_tx_win) { + rxrpc_seq_t tx_bottom = READ_ONCE(call->tx_bottom); + if (_tx_win) - *_tx_win = call->tx_bottom; - return call->tx_prepared - call->tx_bottom < 256; + *_tx_win = tx_bottom; + return call->tx_prepared - tx_bottom < 256; } /* @@ -138,7 +140,7 @@ static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx, rtt = 2; timeout = rtt; - tx_start = smp_load_acquire(&call->acks_hard_ack); + tx_start = READ_ONCE(call->acks_hard_ack); for (;;) { set_current_state(TASK_UNINTERRUPTIBLE); diff --git a/net/rxrpc/txbuf.c b/net/rxrpc/txbuf.c index 8b7c854ed3d75..0cc8f49d69a9e 100644 --- a/net/rxrpc/txbuf.c +++ b/net/rxrpc/txbuf.c @@ -214,14 +214,14 @@ void rxrpc_shrink_call_tx_buffer(struct rxrpc_call *call) while ((txb = list_first_entry_or_null(&call->tx_buffer, struct rxrpc_txbuf, call_link))) { - hard_ack = smp_load_acquire(&call->acks_hard_ack); + hard_ack = call->acks_hard_ack; if (before(hard_ack, txb->seq)) break; if (txb->seq != call->tx_bottom + 1) rxrpc_see_txbuf(txb, rxrpc_txbuf_see_out_of_step); ASSERTCMP(txb->seq, ==, call->tx_bottom + 1); - smp_store_release(&call->tx_bottom, call->tx_bottom + 1); + WRITE_ONCE(call->tx_bottom, call->tx_bottom + 1); list_del_rcu(&txb->call_link); trace_rxrpc_txqueue(call, rxrpc_txqueue_dequeue);