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| author | David S. Miller <davem@davemloft.net> | 2023-06-07 10:09:05 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2023-06-07 10:09:05 +0100 |
| commit | e3144ff52f7d2c884eef352cec9b9ff9acd2eb2f (patch) | |
| tree | a5898632fd2ce3dd1f7dfca691a0a1f6dfdf1231 /net/core/dev.c | |
| parent | Merge tag 'for-net-2023-06-05' of git://git.kernel.org/pub/scm/linux/kernel/g... (diff) | |
| parent | rfs: annotate lockless accesses to RFS sock flow table (diff) | |
| download | linux-e3144ff52f7d2c884eef352cec9b9ff9acd2eb2f.tar.gz linux-e3144ff52f7d2c884eef352cec9b9ff9acd2eb2f.zip | |
Merge branch 'rfs-lockless-annotate'
Eric Dumazet says:
====================
rfs: annotate lockless accesses
rfs runs without locks held, so we should annotate
read and writes to shared variables.
It should prevent compilers forcing writes
in the following situation:
if (var != val)
var = val;
A compiler could indeed simply avoid the conditional:
var = val;
This matters if var is shared between many cpus.
v2: aligns one closing bracket (Simon)
adds Fixes: tags (Jakub)
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 6 |
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; |