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Date:      Fri, 1 Mar 2013 17:10:44 +0000 (UTC)
From:      John Baldwin <jhb@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r247555 - in stable/9/sys: dev/usb/net kern pci sys
Message-ID:  <201303011710.r21HAiq8019330@svn.freebsd.org>
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Author: jhb
Date: Fri Mar  1 17:10:43 2013
New Revision: 247555
URL: http://svnweb.freebsd.org/changeset/base/247555

Log:
  MFC 246037:
  Mark 'ticks', 'time_second', and 'time_uptime' as volatile to prevent the
  compiler from caching their values in tight loops.

Modified:
  stable/9/sys/dev/usb/net/if_cdce.c
  stable/9/sys/kern/kern_clock.c
  stable/9/sys/kern/kern_tc.c
  stable/9/sys/pci/ncr.c
  stable/9/sys/sys/kernel.h
  stable/9/sys/sys/time.h
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/dev/   (props changed)

Modified: stable/9/sys/dev/usb/net/if_cdce.c
==============================================================================
--- stable/9/sys/dev/usb/net/if_cdce.c	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/dev/usb/net/if_cdce.c	Fri Mar  1 17:10:43 2013	(r247555)
@@ -500,6 +500,7 @@ cdce_attach(device_t dev)
 	const struct usb_interface_descriptor *id;
 	const struct usb_cdc_ethernet_descriptor *ued;
 	const struct usb_config *pcfg;
+	uint32_t seed;
 	int error;
 	uint8_t i;
 	uint8_t data_iface_no;
@@ -612,8 +613,9 @@ alloc_transfers:
 		/* fake MAC address */
 
 		device_printf(dev, "faking MAC address\n");
+		seed = ticks;
 		sc->sc_ue.ue_eaddr[0] = 0x2a;
-		memcpy(&sc->sc_ue.ue_eaddr[1], &ticks, sizeof(uint32_t));
+		memcpy(&sc->sc_ue.ue_eaddr[1], &seed, sizeof(uint32_t));
 		sc->sc_ue.ue_eaddr[5] = device_get_unit(dev);
 
 	} else {

Modified: stable/9/sys/kern/kern_clock.c
==============================================================================
--- stable/9/sys/kern/kern_clock.c	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/kern/kern_clock.c	Fri Mar  1 17:10:43 2013	(r247555)
@@ -381,7 +381,7 @@ static void watchdog_config(void *, u_in
 int	stathz;
 int	profhz;
 int	profprocs;
-int	ticks;
+volatile int	ticks;
 int	psratio;
 
 static DPCPU_DEFINE(int, pcputicks);	/* Per-CPU version of ticks. */
@@ -468,7 +468,7 @@ void
 hardclock(int usermode, uintfptr_t pc)
 {
 
-	atomic_add_int((volatile int *)&ticks, 1);
+	atomic_add_int(&ticks, 1);
 	hardclock_cpu(usermode);
 	tc_ticktock(1);
 	cpu_tick_calibration();

Modified: stable/9/sys/kern/kern_tc.c
==============================================================================
--- stable/9/sys/kern/kern_tc.c	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/kern/kern_tc.c	Fri Mar  1 17:10:43 2013	(r247555)
@@ -91,8 +91,8 @@ static struct timecounter *timecounters 
 
 int tc_min_ticktock_freq = 1;
 
-time_t time_second = 1;
-time_t time_uptime = 1;
+volatile time_t time_second = 1;
+volatile time_t time_uptime = 1;
 
 struct bintime boottimebin;
 struct timeval boottime;

Modified: stable/9/sys/pci/ncr.c
==============================================================================
--- stable/9/sys/pci/ncr.c	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/pci/ncr.c	Fri Mar  1 17:10:43 2013	(r247555)
@@ -1386,7 +1386,7 @@ static char *ncr_name (ncb_p np)
  * Kernel variables referenced in the scripts.
  * THESE MUST ALL BE ALIGNED TO A 4-BYTE BOUNDARY.
  */
-static void *script_kvars[] =
+static volatile void *script_kvars[] =
 	{ &time_second, &ticks, &ncr_cache };
 
 static	struct script script0 = {

Modified: stable/9/sys/sys/kernel.h
==============================================================================
--- stable/9/sys/sys/kernel.h	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/sys/kernel.h	Fri Mar  1 17:10:43 2013	(r247555)
@@ -63,7 +63,7 @@ extern int psratio;			/* ratio: prof / s
 extern int stathz;			/* statistics clock's frequency */
 extern int profhz;			/* profiling clock's frequency */
 extern int profprocs;			/* number of process's profiling */
-extern int ticks;
+extern volatile int ticks;
 
 #endif /* _KERNEL */
 

Modified: stable/9/sys/sys/time.h
==============================================================================
--- stable/9/sys/sys/time.h	Fri Mar  1 16:19:09 2013	(r247554)
+++ stable/9/sys/sys/time.h	Fri Mar  1 17:10:43 2013	(r247555)
@@ -281,8 +281,8 @@ struct clockinfo {
 void	inittodr(time_t base);
 void	resettodr(void);
 
-extern time_t	time_second;
-extern time_t	time_uptime;
+extern volatile time_t	time_second;
+extern volatile time_t	time_uptime;
 extern struct bintime boottimebin;
 extern struct timeval boottime;

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