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Groups > linux.kernel > #1350445
| From | David Howells <dhowells@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 09/13] rxrpc: Use ACCESS_ONCE() when accessing circular buffer pointers |
| Date | 2016-03-04 17:40 +0100 |
| Message-ID | <r90VI-14h-33@gated-at.bofh.it> (permalink) |
| References | <r90VH-14h-7@gated-at.bofh.it> |
| Organization | Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 |
Use ACCESS_ONCE() when accessing the other-end pointer into a circular
buffer as it's possible the other-end pointer might change whilst we're
doing this, and if we access it twice, we might get some weird things
happening.
Signed-off-by: David Howells <dhowells@redhat.com>
---
net/rxrpc/ar-output.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/rxrpc/ar-output.c b/net/rxrpc/ar-output.c
index 353f5c9141ea..14c8df6b7f41 100644
--- a/net/rxrpc/ar-output.c
+++ b/net/rxrpc/ar-output.c
@@ -401,7 +401,8 @@ static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
int ret;
_enter(",{%d},%ld",
- CIRC_SPACE(call->acks_head, call->acks_tail, call->acks_winsz),
+ CIRC_SPACE(call->acks_head, ACCESS_ONCE(call->acks_tail),
+ call->acks_winsz),
*timeo);
add_wait_queue(&call->tx_waitq, &myself);
@@ -409,7 +410,7 @@ static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
ret = 0;
- if (CIRC_SPACE(call->acks_head, call->acks_tail,
+ if (CIRC_SPACE(call->acks_head, ACCESS_ONCE(call->acks_tail),
call->acks_winsz) > 0)
break;
if (signal_pending(current)) {
@@ -570,7 +571,8 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
_debug("alloc");
- if (CIRC_SPACE(call->acks_head, call->acks_tail,
+ if (CIRC_SPACE(call->acks_head,
+ ACCESS_ONCE(call->acks_tail),
call->acks_winsz) <= 0) {
ret = -EAGAIN;
if (msg->msg_flags & MSG_DONTWAIT)
@@ -686,7 +688,8 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
sp->hdr.flags = conn->out_clientflag;
if (msg_data_left(msg) == 0 && !more)
sp->hdr.flags |= RXRPC_LAST_PACKET;
- else if (CIRC_SPACE(call->acks_head, call->acks_tail,
+ else if (CIRC_SPACE(call->acks_head,
+ ACCESS_ONCE(call->acks_tail),
call->acks_winsz) > 1)
sp->hdr.flags |= RXRPC_MORE_PACKETS;
if (more && seq & 1)
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[PATCH 09/13] rxrpc: Use ACCESS_ONCE() when accessing circular buffer pointers David Howells <dhowells@redhat.com> - 2016-03-04 17:40 +0100
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