Tejun Heo c0c362b60e libata: implement cross-port EH exclusion ... In libata, the non-EH code paths should always take and release ap->lock explicitly when accessing hardware or shared data structures. However, once EH is active, it's assumed that the port is owned by EH and EH methods don't explicitly take ap->lock unless race from irq handler or other code paths are expected. However, libata EH didn't guarantee exclusion among EHs for ports of the same host. IOW, multiple EHs may execute in parallel on multiple ports of the same controller. In many cases, especially in SATA, the ports are completely independent of each other and this doesn't cause problems; however, there are cases where different ports share the same resource, which lead to obscure timing related bugs such as the one fixed by commit 213373cf (ata_piix: fix locking around SIDPR access). This patch implements exclusion among EHs of the same host. When EH begins, it acquires per-host EH ownership by calling ata_eh_acquire(). When EH finishes, the ownership is released by calling ata_eh_release(). EH ownership is also released whenever the EH thread goes to sleep from ata_msleep() or explicitly and reacquired after waking up. This ensures that while EH is actively accessing the hardware, it has exclusive access to it while allowing EHs to interleave and progress in parallel as they hit waiting stages, which dominate the time spent in EH. This achieves cross-port EH exclusion without pervasive and fragile changes while still allowing parallel EH for the most part. This was first reported by yuanding02@gmail.com more than three years ago in the following bugzilla. :-) https://bugzilla.kernel.org/show_bug.cgi?id=8223 Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Reported-by: yuanding02@gmail.com Signed-off-by: Jeff Garzik <jgarzik@redhat.com>		2010-10-21 20:21:05 -04:00
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acpi	ACPI: Fix typos	2010-09-28 21:38:19 -04:00
asm-generic	gpio: doc updates	2010-09-09 18:57:24 -07:00
crypto
drm	drm/ttm: Fix two race conditions + fix busy codepaths	2010-10-06 09:04:43 +10:00
keys	DNS: Separate out CIFS DNS Resolver code	2010-08-05 17:17:51 +00:00
linux	libata: implement cross-port EH exclusion	2010-10-21 20:21:05 -04:00
math-emu
media	V4L/DVB: videobuf-dma-sg: set correct size in last sg element	2010-09-27 22:22:01 -03:00
mtd	mtd: Update copyright notices	2010-08-08 20:58:20 +01:00
net	Bluetooth: Fix deadlock in the ERTM logic	2010-09-30 12:19:35 -03:00
pcmcia	pcmcia: use struct resource for PCMCIA devices, part 2	2010-08-03 09:04:16 +02:00
rdma	IB: Rename RAW_ETY to RAW_ETHERTYPE	2010-08-04 10:44:19 -07:00
rxrpc
scsi	scsi: use __uX types for headers exported to user space	2010-08-11 08:59:01 -07:00
sound	ALSA: emu10k1 - delay the PCM interrupts (add pcm_irq_delay parameter)	2010-08-18 15:10:59 +02:00
trace	Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2010-08-24 12:21:49 -07:00
video	include: replace unifdef-y with header-y	2010-08-14 22:26:51 +02:00
xen	xen: pvhvm: make it clearer that XEN_UNPLUG_* define bits in a bitfield	2010-08-23 12:01:35 +01:00
Kbuild