Hello.
On 6/17/2015 12:07 AM, Willem de Bruijn wrote:
From: Willem de Bruijn <will...@google.com>
PACKET_FANOUT_LB computes f->rr_cur such that it is modulo
f->num_members. It returns the old value unconditionally, but
f->num_members may have changed since the last store. This can be
fixed with
- return cur
+ return cur < num ? : 0;
When modifying the logic, simplify it further by replacing the loop
with an unconditional atomic increment.
Fixes: dc99f600698d ("packet: Add fanout support.")
Suggested-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: Willem de Bruijn <will...@google.com>
---
net/packet/af_packet.c | 19 ++-----------------
1 file changed, 2 insertions(+), 17 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index b5989c6..efd35e8 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
[...]
@@ -1293,13 +1283,8 @@ static unsigned int fanout_demux_lb(struct packet_fanout
*f,
struct sk_buff *skb,
unsigned int num)
{
- int cur, old;
-
- cur = atomic_read(&f->rr_cur);
- while ((old = atomic_cmpxchg(&f->rr_cur, cur,
- fanout_rr_next(f, num))) != cur)
- cur = old;
- return cur;
+ unsigned int val = atomic_inc_return(&f->rr_cur);
Please insert an empty line after declaration, as it was before your patch.
+ return val % num;
}
[...]
WBR, Sergei
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