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| author | Eric Dumazet <edumazet@google.com> | 2023-06-06 07:41:15 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-06-14 10:57:13 +0200 |
| commit | 28dbabef5bb865c5a573ebee831a4b9f3544e2e1 (patch) | |
| tree | 46c02d2476e000ef4f8e5e006810011cb9e0a7ef /include/linux | |
| parent | 9b3907c57b044d4709fcadd7b0690004fb310962 (diff) | |
| download | linux-stable-28dbabef5bb865c5a573ebee831a4b9f3544e2e1.tar.gz linux-stable-28dbabef5bb865c5a573ebee831a4b9f3544e2e1.tar.bz2 linux-stable-28dbabef5bb865c5a573ebee831a4b9f3544e2e1.zip | |
rfs: annotate lockless accesses to RFS sock flow table
[ Upstream commit 5c3b74a92aa285a3df722bf6329ba7ccf70346d6 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/netdevice.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 4d0f48e74755..64c4ff699e47 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -695,8 +695,11 @@ static inline void rps_record_sock_flow(struct rps_sock_flow_table *table, /* We only give a hint, preemption can change CPU under us */ val |= raw_smp_processor_id(); - if (table->ents[index] != val) - table->ents[index] = val; + /* The following WRITE_ONCE() is paired with the READ_ONCE() + * here, and another one in get_rps_cpu(). + */ + if (READ_ONCE(table->ents[index]) != val) + WRITE_ONCE(table->ents[index], val); } } |