diff options
Diffstat (limited to 'target/linux/generic/backport-5.4/603-v5.12-net-fix-race-between-napi-kthread-mode-and-busy-poll.patch')
| -rw-r--r-- | target/linux/generic/backport-5.4/603-v5.12-net-fix-race-between-napi-kthread-mode-and-busy-poll.patch | 93 |
1 files changed, 0 insertions, 93 deletions
diff --git a/target/linux/generic/backport-5.4/603-v5.12-net-fix-race-between-napi-kthread-mode-and-busy-poll.patch b/target/linux/generic/backport-5.4/603-v5.12-net-fix-race-between-napi-kthread-mode-and-busy-poll.patch deleted file mode 100644 index 764f33e3fc..0000000000 --- a/target/linux/generic/backport-5.4/603-v5.12-net-fix-race-between-napi-kthread-mode-and-busy-poll.patch +++ /dev/null @@ -1,93 +0,0 @@ -From: Wei Wang <weiwan@google.com> -Date: Mon, 1 Mar 2021 17:21:13 -0800 -Subject: [PATCH] net: fix race between napi kthread mode and busy poll - -Currently, napi_thread_wait() checks for NAPI_STATE_SCHED bit to -determine if the kthread owns this napi and could call napi->poll() on -it. However, if socket busy poll is enabled, it is possible that the -busy poll thread grabs this SCHED bit (after the previous napi->poll() -invokes napi_complete_done() and clears SCHED bit) and tries to poll -on the same napi. napi_disable() could grab the SCHED bit as well. -This patch tries to fix this race by adding a new bit -NAPI_STATE_SCHED_THREADED in napi->state. This bit gets set in -____napi_schedule() if the threaded mode is enabled, and gets cleared -in napi_complete_done(), and we only poll the napi in kthread if this -bit is set. This helps distinguish the ownership of the napi between -kthread and other scenarios and fixes the race issue. - -Fixes: 29863d41bb6e ("net: implement threaded-able napi poll loop support") -Reported-by: Martin Zaharinov <micron10@gmail.com> -Suggested-by: Jakub Kicinski <kuba@kernel.org> -Signed-off-by: Wei Wang <weiwan@google.com> -Cc: Alexander Duyck <alexanderduyck@fb.com> -Cc: Eric Dumazet <edumazet@google.com> -Cc: Paolo Abeni <pabeni@redhat.com> -Cc: Hannes Frederic Sowa <hannes@stressinduktion.org> ---- - ---- a/include/linux/netdevice.h -+++ b/include/linux/netdevice.h -@@ -352,6 +352,7 @@ enum { - NAPI_STATE_NO_BUSY_POLL,/* Do not add in napi_hash, no busy polling */ - NAPI_STATE_IN_BUSY_POLL,/* sk_busy_loop() owns this NAPI */ - NAPI_STATE_THREADED, /* The poll is performed inside its own thread*/ -+ NAPI_STATE_SCHED_THREADED, /* Napi is currently scheduled in threaded mode */ - }; - - enum { -@@ -363,6 +364,7 @@ enum { - NAPIF_STATE_NO_BUSY_POLL = BIT(NAPI_STATE_NO_BUSY_POLL), - NAPIF_STATE_IN_BUSY_POLL = BIT(NAPI_STATE_IN_BUSY_POLL), - NAPIF_STATE_THREADED = BIT(NAPI_STATE_THREADED), -+ NAPIF_STATE_SCHED_THREADED = BIT(NAPI_STATE_SCHED_THREADED), - }; - - enum gro_result { ---- a/net/core/dev.c -+++ b/net/core/dev.c -@@ -3921,6 +3921,8 @@ static inline void ____napi_schedule(str - */ - thread = READ_ONCE(napi->thread); - if (thread) { -+ if (thread->state != TASK_INTERRUPTIBLE) -+ set_bit(NAPI_STATE_SCHED_THREADED, &napi->state); - wake_up_process(thread); - return; - } -@@ -6081,7 +6083,8 @@ bool napi_complete_done(struct napi_stru - - WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED)); - -- new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED); -+ new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED | -+ NAPIF_STATE_SCHED_THREADED); - - /* If STATE_MISSED was set, leave STATE_SCHED set, - * because we will call napi->poll() one more time. -@@ -6514,16 +6517,25 @@ static int napi_poll(struct napi_struct - - static int napi_thread_wait(struct napi_struct *napi) - { -+ bool woken = false; -+ - set_current_state(TASK_INTERRUPTIBLE); - - while (!kthread_should_stop() && !napi_disable_pending(napi)) { -- if (test_bit(NAPI_STATE_SCHED, &napi->state)) { -+ /* Testing SCHED_THREADED bit here to make sure the current -+ * kthread owns this napi and could poll on this napi. -+ * Testing SCHED bit is not enough because SCHED bit might be -+ * set by some other busy poll thread or by napi_disable(). -+ */ -+ if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken) { - WARN_ON(!list_empty(&napi->poll_list)); - __set_current_state(TASK_RUNNING); - return 0; - } - - schedule(); -+ /* woken being true indicates this thread owns this napi. */ -+ woken = true; - set_current_state(TASK_INTERRUPTIBLE); - } - __set_current_state(TASK_RUNNING); |