diff mbox series

move smp_rmb() after load of status

Message ID 20180707192319.24771-1-humbabek@gmail.com
State Changes Requested, archived
Delegated to: David Miller
Headers show
Series move smp_rmb() after load of status | expand

Commit Message

humbabek July 7, 2018, 7:23 p.m. UTC 
Signed-off-by: humbabek <humbabek@gmail.com>
---
 net/packet/af_packet.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

Comments

Eric Dumazet July 7, 2018, 10:34 p.m. UTC | #1 
On 07/07/2018 12:23 PM, humbabek wrote:
> Signed-off-by: humbabek <humbabek@gmail.com>
> ---
>

No changelog ?

No comment added explaining why this smp_rmb() move is needed ?
(ie where is the opposite smp_wmb() )

Share with us your thoughts and reasoning, please.
diff mbox series

Patch

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 57634bc3da74..91830ef07c48 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -394,25 +394,30 @@  static void __packet_set_status(struct packet_sock *po, void *frame, int status)
 static int __packet_get_status(struct packet_sock *po, void *frame)
 {
 	union tpacket_uhdr h;
-
-	smp_rmb();
+	int status;
 
 	h.raw = frame;
 	switch (po->tp_version) {
 	case TPACKET_V1:
 		flush_dcache_page(pgv_to_page(&h.h1->tp_status));
-		return h.h1->tp_status;
+		status = h.h1->tp_status;
+		break;
 	case TPACKET_V2:
 		flush_dcache_page(pgv_to_page(&h.h2->tp_status));
-		return h.h2->tp_status;
+		status = h.h2->tp_status;
+		break;
 	case TPACKET_V3:
 		flush_dcache_page(pgv_to_page(&h.h3->tp_status));
-		return h.h3->tp_status;
+		status = h.h3->tp_status;
+		break;
 	default:
 		WARN(1, "TPACKET version not supported.\n");
 		BUG();
-		return 0;
+		status = 0;
+		break;
 	}
+	smp_rmb();
+	return status;
 }
 
 static __u32 tpacket_get_timestamp(struct sk_buff *skb, struct timespec *ts,