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authorEric Dumazet <edumazet@google.com>2023-06-06 10:41:15 +0300
committerDavid S. Miller <davem@davemloft.net>2023-06-07 12:08:45 +0300
commit5c3b74a92aa285a3df722bf6329ba7ccf70346d6 (patch)
treea5898632fd2ce3dd1f7dfca691a0a1f6dfdf1231 /net
parent1e5c647c3f6d4f8497dedcd226204e1880e0ffb3 (diff)
downloadlinux-5c3b74a92aa285a3df722bf6329ba7ccf70346d6.tar.xz
rfs: annotate lockless accesses to RFS sock flow table
Add READ_ONCE()/WRITE_ONCE() on accesses to the sock flow table. This also prevents a (smart ?) compiler to remove the condition in: if (table->ents[index] != newval) table->ents[index] = newval; We need the condition to avoid dirtying a shared cache line. Fixes: fec5e652e58f ("rfs: Receive Flow Steering") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index b3c13e041935..1495f8aff288 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4471,8 +4471,10 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
u32 next_cpu;
u32 ident;
- /* First check into global flow table if there is a match */
- ident = sock_flow_table->ents[hash & sock_flow_table->mask];
+ /* First check into global flow table if there is a match.
+ * This READ_ONCE() pairs with WRITE_ONCE() from rps_record_sock_flow().
+ */
+ ident = READ_ONCE(sock_flow_table->ents[hash & sock_flow_table->mask]);
if ((ident ^ hash) & ~rps_cpu_mask)
goto try_rps;