From c91c46de6bbc1147ae5dfe046b87f5f3d6593215 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Thu, 6 Apr 2023 18:25:33 -0700 Subject: 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 Signed-off-by: Jakub Kicinski --- Documentation/networking/driver.rst | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation') diff --git a/Documentation/networking/driver.rst b/Documentation/networking/driver.rst index 19c363291d04..4071f2c00f8b 100644 --- a/Documentation/networking/driver.rst +++ b/Documentation/networking/driver.rst @@ -104,6 +104,12 @@ and: TX_BUFFS_AVAIL(dp) > 0) netif_wake_queue(dp->dev); +Lockless queue stop / wake helper macros +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/net/netdev_queues.h + :doc: Lockless queue stopping / waking helpers. + No exclusive ownership ---------------------- -- cgit v1.2.3