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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.patch93
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);