don't re-arm fault clearing timer on unrelated netlink events (#2174900)

Resolves: #2174900

linuxptp-faultrearm.patch

@@ -0,0 +1,52 @@
+commit 134dc3c4655fcd9f314a5e56cd50db2f87366f5a
+Author: davidjm via Linuxptp-devel <linuxptp-devel@lists.sourceforge.net>
+Date:   Wed Nov 23 15:50:30 2022 -0800
+
+    Don't re-arm fault clearing timer on unrelated netlink events
+    
+    Set the timer only when an event causes the port to transition to the
+    FAULTY state, rather than potentially re-arming the timeout when an
+    event occurs while the port was already FAULTY.
+    
+    Concretely this occurs when a port is in fault, perhaps due to a
+    single time out while polling for tx-timestamp. If any other port in the
+    system (including unrelated ones ptp4l does not even know about) cause
+    netlink messages to be sent. As it stands, clock_poll() will note that
+    the port is in fault (from before, not due to the current event) and
+    reset the timeout to its original value.
+    
+    If such unrelated netlink messages arrive at a regular enough cadence
+    the timeout may be repeatedly reset, not trigger on time (if at all) and
+    the port may not get a chance to clear its fault, perhaps indefinitely.
+    
+    Signed-off-by: David Mirabito <davidjm@arista.com>
+
+diff --git a/clock.c b/clock.c
+index eea7983..451473e 100644
+--- a/clock.c
++++ b/clock.c
+@@ -1586,6 +1586,7 @@ void clock_set_sde(struct clock *c, int sde)
+ int clock_poll(struct clock *c)
+ {
+ 	int cnt, i;
++	enum port_state prior_state;
+ 	enum fsm_event event;
+ 	struct pollfd *cur;
+ 	struct port *p;
+@@ -1609,6 +1610,7 @@ int clock_poll(struct clock *c)
+ 		/* Let the ports handle their events. */
+ 		for (i = 0; i < N_POLLFD; i++) {
+ 			if (cur[i].revents & (POLLIN|POLLPRI|POLLERR)) {
++				prior_state = port_state(p);
+ 				if (cur[i].revents & POLLERR) {
+ 					pr_err("port %d: unexpected socket error",
+ 					       port_number(p));
+@@ -1624,7 +1626,7 @@ int clock_poll(struct clock *c)
+ 				}
+ 				port_dispatch(p, event, 0);
+ 				/* Clear any fault after a little while. */
+-				if (PS_FAULTY == port_state(p)) {
++				if ((PS_FAULTY == port_state(p)) && (prior_state != PS_FAULTY)) {
+ 					clock_fault_timeout(p, 1);
+ 					break;
+ 				}

linuxptp.spec

@@ -41,6 +41,8 @@ Patch9:		linuxptp-zerolength.patch
 Patch10:	linuxptp-clockcheck.patch
 # handle PHC read failing with EBUSY in phc2sys
 Patch11:	linuxptp-phcerr.patch
+# don't re-arm fault clearing timer on unrelated netlink events
+Patch17:	linuxptp-faultrearm.patch
 
 BuildRequires:	kernel-headers > 4.18.0-87
 BuildRequires:	systemd
@@ -66,6 +68,7 @@ Supporting legacy APIs and other platforms is not a goal.
 %patch9 -p1 -b .zerolength
 %patch10 -p1 -b .clockcheck
 %patch11 -p1 -b .phcerr
+%patch17 -p1 -b .faultrearm
 mv linuxptp-testsuite-%{testsuite_ver}* testsuite
 mv clknetsim-%{clknetsim_ver}* testsuite/clknetsim