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linux/include
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Jianpeng Ma a6ad83fce0 elevator: Fix a race in elevator switching 
commit d50235b7bc upstream.

There's a race between elevator switching and normal io operation.
    Because the allocation of struct elevator_queue and struct elevator_data
    don't in a atomic operation.So there are have chance to use NULL
    ->elevator_data.
    For example:
        Thread A:                               Thread B
        blk_queu_bio                            elevator_switch
        spin_lock_irq(q->queue_block)           elevator_alloc
        elv_merge                               elevator_init_fn

    Because call elevator_alloc, it can't hold queue_lock and the
    ->elevator_data is NULL.So at the same time, threadA call elv_merge and
    nedd some info of elevator_data.So the crash happened.

    Move the elevator_alloc into func elevator_init_fn, it make the
    operations in a atomic operation.

    Using the follow method can easy reproduce this bug
    1:dd if=/dev/sdb of=/dev/null
    2:while true;do echo noop > scheduler;echo deadline > scheduler;done

    The test method also use this method.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Cc: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-20 08:43:03 -07:00
..
acpi ACPI / dock / PCI: Synchronous handling of dock events for PCI devices 2013-06-24 11:22:53 +02:00
asm-generic Merge branch 'fixes' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2013-06-11 11:16:43 -07:00
clocksource ARM: late Exynos multiplatform changes 2013-05-07 11:28:42 -07:00
crypto crypto: sha512 - Expose generic sha512 routine to be callable from other modules 2013-04-25 21:00:57 +08:00
drm Merge branch 'drm-radeon-sun-hainan' of git://people.freedesktop.org/~airlied/linux 2013-05-21 08:50:57 -07:00
dt-bindings ARM: dt: create a DT header for the GIC 2013-04-05 12:23:24 -06:00
keys
linux elevator: Fix a race in elevator switching 2013-08-20 08:43:03 -07:00
math-emu
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2013-06-18 06:25:08 -10:00
memory
misc
net ndisc: Add missing inline to ndisc_addr_option_pad 2013-08-11 18:35:26 -07:00
pcmcia
ras
rdma
rxrpc
scsi Merge branch 'postmerge' into for-linus 2013-05-10 07:54:01 -07:00
sound ASoC: dapm: Treat DAI widgets like AIF widgets for power 2013-06-07 15:54:50 +01:00
target iscsi-target: Fix iscsit_sequence_cmd reject handling for iser 2013-08-04 16:51:17 +08:00
trace Fixed regressions (two stability regressions and a performance 2013-05-14 09:30:54 -07:00
uapi firewire: fix libdc1394/FlyCap2 iso event regression 2013-08-04 16:50:38 +08:00
video Merge branch 'fbdev-3.10-fixes' of git://gitorious.org/linux-omap-dss2/linux into linux-fbdev/for-3.10-fixes 2013-05-29 17:00:34 +08:00
xen xenbus: delay xenbus frontend resume if xenstored is not running 2013-05-29 09:04:19 -04:00
Kbuild UAPI: remove empty Kbuild files 2013-04-30 17:04:09 -07:00