Thread (10 messages) 10 messages, 2 authors, 2019-08-25
STALE2524d
Revisions (2)
  1. v1 current
  2. v2 [diff vs current]

[PATCH bpf-next 1/4] xsk: avoid store-tearing when assigning queues

From: Björn Töpel <hidden>
Date: 2019-08-22 09:13:48
Also in: bpf
Subsystem: networking [general], the rest, xdp sockets (af_xdp) · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski

From: Björn Töpel <redacted>

Use WRITE_ONCE when doing the store of tx, rx, fq, and cq, to avoid
potential store-tearing. These members are read outside of the control
mutex in the mmap implementation.

Fixes: 37b076933a8e ("xsk: add missing write- and data-dependency barrier")
Signed-off-by: Björn Töpel <redacted>
---
 net/xdp/xsk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index ee4428a892fa..f3351013c2a5 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -409,7 +409,7 @@ static int xsk_init_queue(u32 entries, struct xsk_queue **queue,
 
 	/* Make sure queue is ready before it can be seen by others */
 	smp_wmb();
-	*queue = q;
+	WRITE_ONCE(*queue, q);
 	return 0;
 }
 
-- 
2.20.1
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