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authorEric Dumazet <edumazet@google.com>2016-11-16 14:54:50 -0800
committerDavid S. Miller <davem@davemloft.net>2016-11-16 18:32:02 -0500
commit89c4b442b78bdba388337cc746fe63caba85f46c (patch)
tree825a8d6e04cdc937950e9d8a79b52eeb249236c3 /net/core/netpoll.c
parentcadence: Add LSO support. (diff)
downloadlinux-dev-89c4b442b78bdba388337cc746fe63caba85f46c.tar.xz
linux-dev-89c4b442b78bdba388337cc746fe63caba85f46c.zip
netpoll: more efficient locking
Callers of netpoll_poll_lock() own NAPI_STATE_SCHED Callers of netpoll_poll_unlock() have BH blocked between the NAPI_STATE_SCHED being cleared and poll_lock is released. We can avoid the spinlock which has no contention, and use cmpxchg() on poll_owner which we need to set anyway. This removes a possible lockdep violation after the cited commit, since sk_busy_loop() re-enables BH before calling busy_poll_stop() Fixes: 217f69743681 ("net: busy-poll: allow preemption in sk_busy_loop()") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/netpoll.c')
-rw-r--r--net/core/netpoll.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 53599bd0c82d..9424673009c1 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -171,12 +171,12 @@ static void poll_one_napi(struct napi_struct *napi)
static void poll_napi(struct net_device *dev)
{
struct napi_struct *napi;
+ int cpu = smp_processor_id();
list_for_each_entry(napi, &dev->napi_list, dev_list) {
- if (napi->poll_owner != smp_processor_id() &&
- spin_trylock(&napi->poll_lock)) {
+ if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) {
poll_one_napi(napi);
- spin_unlock(&napi->poll_lock);
+ smp_store_release(&napi->poll_owner, -1);
}
}
}