svn commit: r298927 - head/sys/dev/xen/timer

[Roger Pau Monné]

Author: royger
Date: Mon May  2 16:13:55 2016
New Revision: 298927
URL: https://svnweb.freebsd.org/changeset/base/298927

Log:
  xen/timer: remove the timer setup loop
  
  With the removal of the usage of the VCPU_SSHOTTMR_future flag, now
  all errors from xentimer_vcpu_start_timer should be considered fatal, and
  the loop is no longer needed since in case of setting the timer in the past
  we will get an event interrupt right away (instead of returning ETIME).
  
  Sponsored by:	Citrix Systems R&D
  MFC after :	2 weeks

Modified:
  head/sys/dev/xen/timer/timer.c

Modified: head/sys/dev/xen/timer/timer.c
==============================================================================
--- head/sys/dev/xen/timer/timer.c	Mon May  2 16:13:11 2016	(r298926)
+++ head/sys/dev/xen/timer/timer.c	Mon May  2 16:13:55 2016	(r298927)
@@ -76,8 +76,6 @@ static devclass_t xentimer_devclass;
 #define	XENTIMER_MIN_PERIOD_IN_NSEC	100*NSEC_IN_USEC
 #define	XENCLOCK_RESOLUTION		10000000
 
-#define	ETIME	62	/* Xen "bad time" error */
-
 #define	XENTIMER_QUALITY	950
 
 struct xentimer_pcpu_data {
@@ -295,7 +293,7 @@ static int
 xentimer_et_start(struct eventtimer *et,
     sbintime_t first, sbintime_t period)
 {
-	int error = 0, i = 0;
+	int error;
 	struct xentimer_softc *sc = et->et_priv;
 	int cpu = PCPU_GET(vcpu_id);
 	struct xentimer_pcpu_data *pcpu = DPCPU_PTR(xentimer_pcpu);
@@ -312,21 +310,8 @@ xentimer_et_start(struct eventtimer *et,
 	first_in_ns = (((first >> 32) * NSEC_IN_SEC) +
 	               (((uint64_t)NSEC_IN_SEC * (uint32_t)first) >> 32));
 
-	/*
-	 * Retry any timer scheduling failures, where the hypervisor
-	 * returns -ETIME.  Sometimes even a 100us timer period isn't large
-	 * enough, but larger period instances are relatively uncommon.
-	 *
-	 * XXX Remove the panics once et_start() and its consumers are
-	 *     equipped to deal with start failures.
-	 */
-	do {
-		if (++i == 60)
-			panic("can't schedule timer");
-		next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns;
-		error = xentimer_vcpu_start_timer(cpu, next_time);
-	} while (error == -ETIME);
-
+	next_time = xen_fetch_vcpu_time(vcpu) + first_in_ns;
+	error = xentimer_vcpu_start_timer(cpu, next_time);
 	if (error)
 		panic("%s: Error %d setting singleshot timer to %"PRIu64"\n",
 		    device_get_nameunit(sc->dev), error, next_time);