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| H A D | tun.c | diff 4ffdd22e49f47db543906d75453a0048a53071ab Wed Oct 09 11:20:02 CDT 2019 Eric Dumazet <edumazet@google.com> tun: remove possible false sharing in tun_flow_update()
As mentioned in https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE#it-may-improve-performance
a C compiler can legally transform
if (e->queue_index != queue_index)
e->queue_index = queue_index;
to :
e->queue_index = queue_index;
Note that the code using jiffies has no issue, since jiffies
has volatile attribute.
if (e->updated != jiffies)
e->updated = jiffies;
Fixes: 83b1bc122cab ("tun: align write-heavy flow entry members to a cache line")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Zhang Yu <zhangyu31@baidu.com>
Cc: Wang Li <wangli39@baidu.com>
Cc: Li RongQing <lirongqing@baidu.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
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