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From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: Justin Forbes <jmforbes@linuxtx.org>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Dave Jones <davej@redhat.com>,
	Chuck Wolber <chuckw@quantumlinux.com>,
	Chris Wedgwood <reviews@ml.cw.f00f.org>,
	Michael Krufky <mkrufky@linuxtv.org>,
	Chuck Ebbert <cebbert@redhat.com>,
	Domenico Andreoli <cavokz@gmail.com>, Willy Tarreau <w@1wt.eu>,
	Rodrigo Rubira Branco <rbranco@la.checkpoint.com>,
	Jake Edge <jake@lwn.net>, Eugene Teo <eteo@redhat.com>,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk, Peter Zijlstra <peterz@infradead.org>,
	Molnar <mingo@elte.hu>,
	Ingo@hera.kernel.org, Dave Kleikamp <shaggy@linux.vnet.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [patch 40/57] sched_clock: prevent scd->clock from moving backwards
Date: Tue, 4 Nov 2008 15:33:01 -0800	[thread overview]
Message-ID: <20081104233301.GO659@suse.de> (raw)
In-Reply-To: <20081104233028.GA659@suse.de>

[-- Attachment #1: sched_clock-prevent-scd-clock-from-moving-backwards.patch --]
[-- Type: text/plain, Size: 1606 bytes --]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

commit 5b7dba4ff834259a5623e03a565748704a8fe449 upstream

sched_clock: prevent scd->clock from moving backwards

When sched_clock_cpu() couples the clocks between two cpus, it may
increment scd->clock beyond the GTOD tick window that __update_sched_clock()
uses to clamp the clock.  A later call to __update_sched_clock() may move
the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's
monotonic property.

This patch ensures that scd->clock will not be set backward.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 kernel/sched_clock.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -118,13 +118,13 @@ static u64 __update_sched_clock(struct s
 
 	/*
 	 * scd->clock = clamp(scd->tick_gtod + delta,
-	 * 		      max(scd->tick_gtod, scd->clock),
-	 * 		      scd->tick_gtod + TICK_NSEC);
+	 *		      max(scd->tick_gtod, scd->clock),
+	 *		      max(scd->clock, scd->tick_gtod + TICK_NSEC));
 	 */
 
 	clock = scd->tick_gtod + delta;
 	min_clock = wrap_max(scd->tick_gtod, scd->clock);
-	max_clock = scd->tick_gtod + TICK_NSEC;
+	max_clock = wrap_max(scd->clock, scd->tick_gtod + TICK_NSEC);
 
 	clock = wrap_max(clock, min_clock);
 	clock = wrap_min(clock, max_clock);

-- 

  parent reply	other threads:[~2008-11-04 23:52 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20081104232144.186593464@mini.kroah.org>
2008-11-04 23:30 ` [patch 00/57] 2.6.27-stable review Greg KH
2008-11-04 23:30   ` [patch 01/57] agp: Fix stolen memory counting on G4X Greg KH
2008-11-04 23:30   ` [patch 02/57] SCSI: sd: Fix handling of NO_SENSE check condition Greg KH
2008-11-04 23:31   ` [patch 03/57] S390: Fix sysdev class file creation Greg KH
2008-11-04 23:31   ` [patch 04/57] sysfs: Fix return values for sysdev_store_{ulong, int} Greg KH
2008-11-04 23:31   ` [patch 05/57] ipmi: add MODULE_ALIAS to load ipmi_devintf with ipmi_si Greg KH
2008-11-04 23:31   ` [patch 06/57] USB: fix crash when URBs are unlinked after the device is gone Greg KH
2008-11-04 23:31   ` [patch 07/57] ALSA: hda - Add reboot notifier Greg KH
2008-11-04 23:31   ` [patch 08/57] kbuild: mkspec - fix build rpm Greg KH
2008-11-04 23:31   ` [patch 09/57] x86: fix /dev/mem mmap breakage when PAT is disabled Greg KH
2008-11-04 23:31   ` [patch 10/57] atl1: fix vlan tag regression Greg KH
2008-11-04 23:31   ` [patch 11/57] libertas: fix buffer overrun Greg KH
2008-11-04 23:31   ` [patch 12/57] Revert "HID: Invert HWHEEL mappings for some Logitech mice" Greg KH
2008-11-04 23:31   ` [patch 13/57] libata: initialize port_task when !CONFIG_ATA_SFF Greg KH
2008-11-04 23:31   ` [patch 14/57] syncookies: fix inclusion of tcp options in syn-ack Greg KH
2008-11-04 23:31   ` [patch 15/57] tcp: Restore ordering of TCP options for the sake of inter-operability Greg KH
2008-11-04 23:31   ` [patch 16/57] tcpv6: fix option space offsets with md5 Greg KH
2008-11-04 23:31   ` [patch 17/57] pkt_sched: sch_generic: Fix oops in sch_teql Greg KH
2008-11-04 23:31   ` [patch 18/57] sparc64: Fix race in arch/sparc64/kernel/trampoline.S Greg KH
2008-11-04 23:31   ` [patch 19/57] math-emu: Fix signalling of underflow and inexact while packing result Greg KH
2008-11-04 23:31   ` [patch 20/57] firewire: fix setting tag and sy in iso transmission Greg KH
2008-11-04 23:31   ` [patch 21/57] firewire: fix ioctl() return code Greg KH
2008-11-04 23:31   ` [patch 22/57] firewire: Survive more than 256 bus resets Greg KH
2008-11-04 23:31   ` [patch 23/57] firewire: fix struct fw_node memory leak Greg KH
2008-11-04 23:31   ` [patch 24/57] firewire: fw-sbp2: delay first login to avoid retries Greg KH
2008-11-04 23:31   ` [patch 25/57] firewire: fw-sbp2: fix races Greg KH
2008-11-04 23:31   ` [patch 26/57] ACPI: Always report a sync event after a lid state change Greg KH
2008-11-04 23:31   ` [patch 27/57] powerpc: fix i2c on PPC linkstation / kurobox machines Greg KH
2008-11-04 23:31   ` [patch 28/57] powerpc: Reserve in bootmem lmb reserved regions that cross NUMA nodes Greg KH
2008-11-04 23:32   ` [patch 29/57] powerpc/numa: Make memory reserve code more robust Greg KH
2008-11-04 23:32   ` [patch 30/57] powerpc: Dont use a 16G page if beyond mem= limits Greg KH
2008-11-04 23:32   ` [patch 31/57] i2c: The i2c mailing list is moving Greg KH
2008-11-04 23:32   ` [patch 32/57] scx200_i2c: Add missing class parameter Greg KH
2008-11-04 23:32   ` [patch 33/57] ALSA: use correct lock in snd_ctl_dev_disconnect() Greg KH
2008-11-04 23:32   ` [patch 34/57] V4L: pvrusb2: Keep MPEG PTSs from drifting away Greg KH
2008-11-04 23:32   ` [patch 35/57] DVB: s5h1411: bugfix: Setting serial or parallel mode could destroy bits Greg KH
2008-11-04 23:32   ` [patch 36/57] DVB: s5h1411: Perform s5h1411 soft reset after tuning Greg KH
2008-11-04 23:32   ` [patch 37/57] DVB: s5h1411: Power down s5h1411 when not in use Greg KH
2008-11-04 23:32   ` [patch 38/57] PCI: fix 64-vbit prefetchable memory resource BARs Greg KH
2008-11-04 23:32   ` [patch 39/57] sched: disable the hrtick for now Greg KH
2008-11-04 23:33   ` Greg KH [this message]
2008-11-04 23:33   ` [patch 41/57] x86: avoid dereferencing beyond stack + THREAD_SIZE Greg KH
2008-11-04 23:33   ` [patch 42/57] rtc-cmos: look for PNP RTC first, then for platform RTC Greg KH
2008-11-04 23:33   ` [patch 43/57] USB: storage: Avoid I/O errors when issuing SCSI ioctls to JMicron USB/ATA bridge Greg KH
2008-11-04 23:33   ` [patch 44/57] x86: register a platform RTC device if PNP doesnt describe it Greg KH
2008-11-04 23:33   ` [patch 45/57] sata_promise: add ATA engine reset to reset ops Greg KH
2008-11-04 23:33   ` [patch 46/57] sata_nv: fix generic, nf2/3 detection regression Greg KH
2008-11-04 23:33   ` [patch 47/57] ACPI: EC: do transaction from interrupt context Greg KH
2008-11-04 23:33   ` [patch 48/57] ACPI: EC: Rename some variables Greg KH
2008-11-04 23:33   ` [patch 49/57] ACPI: EC: Check for IBF=0 periodically if not in GPE mode Greg KH
2008-11-04 23:33   ` [patch 50/57] libata: Fix LBA48 on pata_it821x RAID volumes Greg KH
2008-11-04 23:33   ` [patch 51/57] ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism Greg KH
2008-11-05  0:48     ` Zhao Yakui
2008-11-05  1:02       ` Greg KH
2008-11-04 23:33   ` [patch 52/57] ACPI: Clear WAK_STS on resume Greg KH
2008-11-04 23:33   ` [patch 53/57] Input: atkbd - expand Latitudes force release quirk to other Dells Greg KH
2008-11-04 23:33   ` [patch 54/57] hfsplus: fix Buffer overflow with a corrupted image Greg KH
2008-11-04 23:33   ` [patch 55/57] hfsplus: check read_mapping_page() return value Greg KH
2008-11-04 23:33   ` [patch 56/57] bonding: fix panic when taking bond interface down before removing module Greg KH
2008-11-04 23:33   ` [patch 57/57] file caps: always start with clear bprm->caps_* Greg KH

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