Linus Torvalds 2cec670116 Fix __read_seqcount_begin() to use ACCESS_ONCE for sequence value read ... commit 2f62427862 upstream. We really need to use a ACCESS_ONCE() on the sequence value read in __read_seqcount_begin(), because otherwise the compiler might end up reloading the value in between the test and the return of it. As a result, it might end up returning an odd value (which means that a write is in progress). If the reader is then fast enough that that odd value is still the current one when the read_seqcount_retry() is done, we might end up with a "successful" read sequence, even despite the concurrent write being active. In practice this probably never really happens - there just isn't anything else going on around the read of the sequence count, and the common case is that we end up having a read barrier immediately afterwards. So the code sequence in which gcc might decide to reaload from memory is small, and there's no reason to believe it would ever actually do the reload. But if the compiler ever were to decide to do so, it would be incredibly annoying to debug. Let's just make sure. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2012-05-21 09:39:58 -07:00
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acpi	ACPI: Store SRAT table revision	2012-01-25 17:24:57 -08:00
asm-generic	asm-generic: Use __BITS_PER_LONG in statfs.h	2012-05-21 09:39:58 -07:00
crypto
drm	drm: Fix authentication kernel crash	2012-02-03 09:18:52 -08:00
keys
linux	Fix __read_seqcount_begin() to use ACCESS_ONCE for sequence value read	2012-05-21 09:39:58 -07:00
math-emu
media	[media] tuner-core/v4l2-subdev: document that the type field has to be filled in	2011-07-07 15:04:23 -03:00
mtd
net	Bluetooth: hci_core: fix NULL-pointer dereference at unregister	2012-04-22 16:21:42 -07:00
pcmcia
rdma	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband	2011-05-26 12:13:57 -07:00
rxrpc
scsi	[SCSI] libsas: Add option for SATA soft reset	2011-05-26 22:49:33 -05:00
sound	ALSA: sb16 - Fix build errors on MIPS and others with 13bit ioctl size	2011-06-30 15:33:57 +02:00
target	target: Set additional sense length field in sense data	2012-01-25 17:25:00 -08:00
trace	writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue	2012-02-20 12:48:11 -08:00
video	OMAPDSS: HDMI: PHY burnout fix	2012-03-12 10:32:59 -07:00
xen	xen/xenbus: Reject replies with payload > XENSTORE_PAYLOAD_MAX.	2012-01-25 17:24:41 -08:00
Kbuild