Module Name: src
Committed By: knakahara
Date: Mon Sep 7 09:14:54 UTC 2020
Modified Files:
src/sys/dev/pci/ixgbe: ixgbe.c
Log Message:
Fix race between ixgbe_msix_admin() and ixgbe_handle_admin(), pointed out by
ozaki-r@n.o.
The race is caused by the following.
CPU#A processes workqueue, CPU#B processes admin interrupt.
(0) one of CPUs already calls ixgbe_schedule_admin_tasklet()
such as ixgbe_handle_timer()
(1) CPU#A: read adapter->task_requests
(2) CPU#B: set adapter->task_requests
(3) CPU#B: read(and try to set) adapter->admin_pending
but adapter->admin_pending is set, so does not
call workqueue_enqueue()
(4) CPU#A: clear adapter->admin_pending
that is, the tasks set by (2) is not processed as missfire workqueue by (3).
To generate a diff of this commit:
cvs rdiff -u -r1.257 -r1.258 src/sys/dev/pci/ixgbe/ixgbe.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/dev/pci/ixgbe/ixgbe.c
diff -u src/sys/dev/pci/ixgbe/ixgbe.c:1.257 src/sys/dev/pci/ixgbe/ixgbe.c:1.258
--- src/sys/dev/pci/ixgbe/ixgbe.c:1.257 Mon Sep 7 05:50:58 2020
+++ src/sys/dev/pci/ixgbe/ixgbe.c Mon Sep 7 09:14:53 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: ixgbe.c,v 1.257 2020/09/07 05:50:58 msaitoh Exp $ */
+/* $NetBSD: ixgbe.c,v 1.258 2020/09/07 09:14:53 knakahara Exp $ */
/******************************************************************************
@@ -4805,6 +4805,13 @@ ixgbe_handle_admin(struct work *wk, void
*/
IFNET_LOCK(ifp);
IXGBE_CORE_LOCK(adapter);
+ /*
+ * Clear the admin_pending flag before reading task_requests to avoid
+ * missfiring workqueue though setting task_request.
+ * Hmm, ixgbe_schedule_admin_tasklet() can extra-fire though
+ * task_requests are done by prior workqueue, but it is harmless.
+ */
+ atomic_store_relaxed(&adapter->admin_pending, 0);
while ((req =
(adapter->task_requests & ~IXGBE_REQUEST_TASK_NEED_ACKINTR))
!= 0) {
@@ -4841,7 +4848,6 @@ ixgbe_handle_admin(struct work *wk, void
}
#endif
}
- atomic_store_relaxed(&adapter->admin_pending, 0);
if ((adapter->task_requests & IXGBE_REQUEST_TASK_NEED_ACKINTR) != 0) {
atomic_and_32(&adapter->task_requests,
~IXGBE_REQUEST_TASK_NEED_ACKINTR);
