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| author | Jakub Kicinski <kuba@kernel.org> | 2021-09-24 13:24:53 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-09-27 12:19:11 +0100 |
| commit | 719c571970109b0d0af24745d31b202affc9365f (patch) | |
| tree | d10efe389dc5db0a16662596bfc79ebd9f34e62a /net/core | |
| parent | 930dfa563155179861470b2aba880eac2ae30bfb (diff) | |
| download | linux-719c571970109b0d0af24745d31b202affc9365f.tar.gz linux-719c571970109b0d0af24745d31b202affc9365f.tar.bz2 linux-719c571970109b0d0af24745d31b202affc9365f.zip | |
net: make napi_disable() symmetric with enable
Commit 3765996e4f0b ("napi: fix race inside napi_enable") fixed
an ordering bug in napi_enable() and made the napi_enable() diverge
from napi_disable(). The state transitions done on disable are
not symmetric to enable.
There is no known bug in napi_disable() this is just refactoring.
Eric suggests we can also replace msleep(1) with a more opportunistic
usleep_range().
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/dev.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 62ddd7d6e00d..fa989ab63f29 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6900,19 +6900,25 @@ EXPORT_SYMBOL(netif_napi_add); void napi_disable(struct napi_struct *n) { + unsigned long val, new; + might_sleep(); set_bit(NAPI_STATE_DISABLE, &n->state); - while (test_and_set_bit(NAPI_STATE_SCHED, &n->state)) - msleep(1); - while (test_and_set_bit(NAPI_STATE_NPSVC, &n->state)) - msleep(1); + do { + val = READ_ONCE(n->state); + if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) { + usleep_range(20, 200); + continue; + } + + new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC; + new &= ~(NAPIF_STATE_THREADED | NAPIF_STATE_PREFER_BUSY_POLL); + } while (cmpxchg(&n->state, val, new) != val); hrtimer_cancel(&n->timer); - clear_bit(NAPI_STATE_PREFER_BUSY_POLL, &n->state); clear_bit(NAPI_STATE_DISABLE, &n->state); - clear_bit(NAPI_STATE_THREADED, &n->state); } EXPORT_SYMBOL(napi_disable); |