diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2023-04-06 18:25:33 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2023-04-10 17:56:18 -0700 |
| commit | c91c46de6bbc1147ae5dfe046b87f5f3d6593215 (patch) | |
| tree | 991868725389937ee41fa504abdc098e5d4360e5 /include/linux/netdevice.h | |
| parent | 8336462539ae751cbf7d59822eb331602a69df99 (diff) | |
net: provide macros for commonly copied lockless queue stop/wake code
A lot of drivers follow the same scheme to stop / start queues
without introducing locks between xmit and NAPI tx completions.
I'm guessing they all copy'n'paste each other's code.
The original code dates back all the way to e1000 and Linux 2.6.19.
Smaller drivers shy away from the scheme and introduce a lock
which may cause deadlocks in netpoll.
Provide macros which encapsulate the necessary logic.
The macros do not prevent false wake ups, the extra barrier
required to close that race is not worth it. See discussion in:
https://lore.kernel.org/all/c39312a2-4537-14b4-270c-9fe1fbb91e89@gmail.com/
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux/netdevice.h')
| -rw-r--r-- | include/linux/netdevice.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 1c25b39681b3..7bec9a2be8ef 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3335,6 +3335,7 @@ static inline void netif_tx_wake_all_queues(struct net_device *dev) static __always_inline void netif_tx_stop_queue(struct netdev_queue *dev_queue) { + /* Must be an atomic op see netif_txq_try_stop() */ set_bit(__QUEUE_STATE_DRV_XOFF, &dev_queue->state); } |