I hit an hangup on napi_disable(), when the threaded
mode is enabled and the napi is under heavy traffic.
If the relevant napi has been scheduled and the napi_disable()
kicks in before the next napi_threaded_wait() completes - so
that the latter quits due to the napi_disable_pending() condition,
the existing code leaves the NAPI_STATE_SCHED bit set and the
napi_disable() loop waiting for such bit will hang.
Address the issue explicitly clearing the SCHED_BIT on napi_thread
termination, if the thread is owns the napi.
Fixes: 29863d41bb6e ("net: implement threaded-able napi poll loop support")
Signed-off-by: Paolo Abeni <pab...@redhat.com>
---
net/core/dev.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index b4c67a5be606d..e2e716ba027b8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7059,6 +7059,14 @@ static int napi_thread_wait(struct napi_struct *napi)
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
+
+ /* if the thread owns this napi, and the napi itself has been disabled
+ * in-between napi_schedule() and the above napi_disable_pending()
+ * check, we need to clear the SCHED bit here, or napi_disable
+ * will hang waiting for such bit being cleared
+ */
+ if (test_bit(NAPI_STATE_SCHED_THREADED, &napi->state) || woken)
+ clear_bit(NAPI_STATE_SCHED, &napi->state);
return -1;
}
--
2.26.2
