1. 29 10月, 2013 1 次提交
  2. 28 10月, 2013 9 次提交
  3. 27 10月, 2013 1 次提交
    • H
      parisc: Do not crash 64bit SMP kernels on machines with >= 4GB RAM · 54e181e0
      Helge Deller 提交于
      Since the beginning of the parisc-linux port, sometimes 64bit SMP kernels were
      not able to bring up other CPUs than the monarch CPU and instead crashed the
      kernel.  The reason was unclear, esp. since it involved various machines (e.g.
      J5600, J6750 and SuperDome). Testing showed, that those crashes didn't happened
      when less than 4GB were installed, or if a 32bit Linux kernel was booted.
      
      In the end, the fix for those SMP problems is trivial:
      During the early phase of the initialization of the CPUs, including the monarch
      CPU, the PDC_PSW firmware function to enable WIDE (=64bit) mode is called.
      It's documented that this firmware function may clobber various registers, and
      one one of those possibly clobbered registers is %cr30 which holds the task
      thread info pointer.
      
      Now, if %cr30 would always have been clobbered, then this bug would have been
      detected much earlier. But lots of testing finally showed, that - at least for
      %cr30 - on some machines only the upper 32bits of the 64bit register suddenly
      turned zero after the firmware call.
      
      So, after finding the root cause, the explanation for the various crashes
      became clear:
      - On 32bit SMP Linux kernels all upper 32bit were zero, so we didn't faced this
        problem.
      - Monarch CPUs in 64bit mode always booted sucessfully, because the inital task
        thread info pointer was below 4GB.
      - Secondary CPUs booted sucessfully on machines with less than 4GB RAM because
        the upper 32bit were zero anyay.
      - Secondary CPus failed to boot if we had more than 4GB RAM and the task thread
        info pointer was located above the 4GB boundary.
      
      Finally, the patch to fix this problem is trivial by saving the %cr30 register
      before the firmware call and restoring it afterwards.
      Signed-off-by: NHelge Deller <deller@gmx.de>
      Signed-off-by: NJohn David Anglin <dave.anglin@bell.net>
      Cc: <stable@vger.kernel.org> # 2.6.12+
      Signed-off-by: NHelge Deller <deller@gmx.de>
      54e181e0
  4. 26 10月, 2013 6 次提交
    • L
      Merge tag 'pm+acpi-3.12-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · 20582e34
      Linus Torvalds 提交于
      Pull ACPI and power management fixes from
       "These fix two bugs in the intel_pstate driver, a hibernate bug leading
        to nasty resume failures sometimes and acpi-cpufreq initialization bug
        that causes problems to happen during module unload when intel_pstate
        is in use.
      
        Specifics:
      
         - Fix for rounding errors in intel_pstate causing CPU utilization to
           be underestimated from Brennan Shacklett.
      
         - intel_pstate fix to always use the correct max pstate value when
           computing the min pstate from Dirk Brandewie.
      
         - Hibernation fix for deadlocking resume in cases when the probing of
           the device containing the image is deferred from Russ Dill.
      
         - acpi-cpufreq fix to prevent the module from staying in memory when
           the driver cannot be registered and then attempting to unregister
           things that have never been registered on exit"
      
      * tag 'pm+acpi-3.12-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
        acpi-cpufreq: Fail initialization if driver cannot be registered
        PM / hibernate: Move software_resume to late_initcall_sync
        intel_pstate: Correct calculation of min pstate value
        intel_pstate: Improve accuracy by not truncating until final result
      20582e34
    • L
      Merge tag 'for-linus-20131025' of git://git.infradead.org/linux-mtd · d255c59a
      Linus Torvalds 提交于
      Pull final mtd fixes from Brian Norris:
       "A few more last-minute regression fixes, prepared jointly by me and
        David Woodhouse:
      
         - Revert pxa3xx to its old name to avoid breaking existing
           'mtdparts=' boot strings.
      
         - Return GPMI NAND to its legacy ECC layout for backwards
           compatibility.  We will revisit this in 3.13.
      
        A note from David on the latter fix: 'This leaves a harmless cosmetic
        warning about an unused function.  At this point in the cycle I really
        don't care.'"
      
      * tag 'for-linus-20131025' of git://git.infradead.org/linux-mtd:
        mtd: gpmi: fix ECC regression
        mtd: nand: pxa3xx: Fix registered MTD name
      d255c59a
    • N
      vhost/scsi: Fix incorrect usage of get_user_pages_fast write parameter · 60a01f55
      Nicholas Bellinger 提交于
      This patch addresses a long-standing bug where the get_user_pages_fast()
      write parameter used for setting the underlying page table entry permission
      bits was incorrectly set to write=1 for data_direction=DMA_TO_DEVICE, and
      passed into get_user_pages_fast() via vhost_scsi_map_iov_to_sgl().
      
      However, this parameter is intended to signal WRITEs to pinned userspace
      PTEs for the virtio-scsi DMA_FROM_DEVICE -> READ payload case, and *not*
      for the virtio-scsi DMA_TO_DEVICE -> WRITE payload case.
      
      This bug would manifest itself as random process segmentation faults on
      KVM host after repeated vhost starts + stops and/or with lots of vhost
      endpoints + LUNs.
      
      Cc: Stefan Hajnoczi <stefanha@redhat.com>
      Cc: Michael S. Tsirkin <mst@redhat.com>
      Cc: Asias He <asias@redhat.com>
      Cc: <stable@vger.kernel.org> # 3.6+
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      60a01f55
    • W
      target/pscsi: fix return value check · 58932e96
      Wei Yongjun 提交于
      In case of error, the function scsi_host_lookup() returns NULL
      pointer not ERR_PTR(). The IS_ERR() test in the return value check
      should be replaced with NULL test.
      Signed-off-by: NWei Yongjun <yongjun_wei@trendmicro.com.cn>
      Cc: <stable@vger.kernel.org>
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      58932e96
    • L
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · f55ac56d
      Linus Torvalds 提交于
      Pull vfs fixes (try two) from Al Viro:
       "nfsd performance regression fix + seq_file lseek(2) fix"
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        seq_file: always update file->f_pos in seq_lseek()
        nfsd regression since delayed fput()
      f55ac56d
    • D
      mtd: gpmi: fix ECC regression · 031e2777
      David Woodhouse 提交于
      The "legacy" ECC layout used until 3.12-rc1 uses all the OOB area by
      computing the ECC strength and ECC step size ourselves.
      
      Commit 2febcdf8 ("mtd: gpmi: set the BCHs geometry with the ecc info")
      makes the driver use the ECC info (ECC strength and ECC step size)
      provided by the MTD code, and creates a different NAND ECC layout
      for the BCH, and use the new ECC layout. This causes a regression:
      
         We can not mount the ubifs which was created by the old NAND ECC layout.
      
      This patch fixes this issue by reverting to the legacy ECC layout.
      
      We will probably introduce a new device-tree property to indicate that
      the new ECC layout can be used. For now though, for the imminent 3.12
      release, we just unconditionally revert to the 3.11 behaviour.
      
      This leaves a harmless cosmetic warning about an unused function. At
      this point in the cycle I really don't care.
      Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
      Signed-off-by: NBrian Norris <computersforpeace@gmail.com>
      Acked-by: NHuang Shijie <b32955@freescale.com>
      Acked-by: NMarek Vasut <marex@denx.de>
      Tested-by: NMarek Vasut <marex@denx.de>
      031e2777
  5. 25 10月, 2013 9 次提交
  6. 24 10月, 2013 13 次提交
    • J
      perf script python: Fix mem leak due to missing Py_DECREFs on dict entries · c0268e8d
      Joseph Schuchart 提交于
      We are using the Python scripting interface in perf to extract kernel
      events relevant for performance analysis of HPC codes. We noticed that
      the "perf script" call allocates a significant amount of memory (in the
      order of several 100 MiB) during it's run, e.g. 125 MiB for a 25 MiB
      input file:
      
        $> perf record -o perf.data -a -R -g fp \
             -e power:cpu_frequency -e sched:sched_switch \
             -e sched:sched_migrate_task -e sched:sched_process_exit \
             -e sched:sched_process_fork -e sched:sched_process_exec \
             -e cycles  -m 4096 --freq 4000
        $> /usr/bin/time perf script -i perf.data -s dummy_script.py
        0.84user 0.13system 0:01.92elapsed 51%CPU (0avgtext+0avgdata
        125532maxresident)k
        73072inputs+0outputs (57major+33086minor)pagefaults 0swaps
      
      Upon further investigation using the valgrind massif tool, we noticed
      that Python objects that are created in trace-event-python.c via
      PyString_FromString*() (and their Integer and Long counterparts) are
      never free'd.
      
      The reason for this seem to be missing Py_DECREF calls on the objects
      that are returned by these functions and stored in the Python
      dictionaries. The Python dictionaries do not steal references (as
      opposed to Python tuples and lists) but instead add their own reference.
      
      Hence, the reference that is returned by these object creation functions
      is never released and the memory is leaked. (see [1,2])
      
      The attached patch fixes this by wrapping all relevant calls to
      PyDict_SetItemString() and decrementing the reference counter
      immediately after the Python function call.
      
      This reduces the allocated memory to a reasonable amount:
      
        $> /usr/bin/time perf script -i perf.data -s dummy_script.py
        0.73user 0.05system 0:00.79elapsed 99%CPU (0avgtext+0avgdata
        49132maxresident)k
        0inputs+0outputs (0major+14045minor)pagefaults 0swaps
      
      For comparison, with a 120 MiB input file the memory consumption
      reported by time drops from almost 600 MiB to 146 MiB.
      
      The patch has been tested using Linux 3.8.2 with Python 2.7.4 and Linux
      3.11.6 with Python 2.7.5.
      
      Please let me know if you need any further information.
      
      [1] http://docs.python.org/2/c-api/tuple.html#PyTuple_SetItem
      [2] http://docs.python.org/2/c-api/dict.html#PyDict_SetItemStringSigned-off-by: NJoseph Schuchart <joseph.schuchart@tu-dresden.de>
      Reviewed-by: NTom Zanussi <tom.zanussi@linux.intel.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
      Link: http://lkml.kernel.org/r/1381468543-25334-4-git-send-email-namhyung@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
      c0268e8d
    • N
      target: Fail XCOPY for non matching source + destination block_size · 48502ddb
      Nicholas Bellinger 提交于
      This patch adds an explicit check + failure for XCOPY I/O to source +
      destination devices with a non-matching block_size.
      
      This limitiation is currently due to the fact that the scatterlist
      memory allocated for the XCOPY READ operation is passed zero-copy
      to the XCOPY WRITE operation.
      Reported-by: NThomas Glanzmann <thomas@glanzmann.de>
      Reported-by: NDouglas Gilbert <dgilbert@interlog.com>
      Cc: Thomas Glanzmann <thomas@glanzmann.de>
      Cc: Douglas Gilbert <dgilbert@interlog.com>
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      48502ddb
    • N
      target: Generate failure for XCOPY I/O with non-zero scsi_status · 8a955d6d
      Nicholas Bellinger 提交于
      This patch adds the missing non-zero se_cmd->scsi_status check required
      for local XCOPY I/O within target_xcopy_issue_pt_cmd() to signal an
      exception case failure.
      
      This will trigger the generation of SAM_STAT_CHECK_CONDITION status
      from within target_xcopy_do_work() process context code.
      Reported-by: NThomas Glanzmann <thomas@glanzmann.de>
      Reported-by: NDouglas Gilbert <dgilbert@interlog.com>
      Cc: Thomas Glanzmann <thomas@glanzmann.de>
      Cc: Douglas Gilbert <dgilbert@interlog.com>
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      8a955d6d
    • N
      target: Add missing XCOPY I/O operation sense_buffer · 366bda19
      Nicholas Bellinger 提交于
      This patch adds the missing xcopy_pt_cmd->sense_buffer[] required for
      correctly handling CHECK_CONDITION exceptions within the locally
      generated XCOPY I/O path.
      
      Also update target_xcopy_read_source() + target_xcopy_setup_pt_cmd()
      to pass this buffer into transport_init_se_cmd() to correctly setup
      se_cmd->sense_buffer.
      Reported-by: NThomas Glanzmann <thomas@glanzmann.de>
      Reported-by: NDouglas Gilbert <dgilbert@interlog.com>
      Cc: Thomas Glanzmann <thomas@glanzmann.de>
      Cc: Douglas Gilbert <dgilbert@interlog.com>
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      366bda19
    • L
      Merge tag 'md/3.12-fixes' of git://neil.brown.name/md · e6036c0b
      Linus Torvalds 提交于
      Pull md bugfixes from Neil Brown:
       "Assorted md bug-fixes for 3.12.
      
        All tagged for -stable releases too"
      
      * tag 'md/3.12-fixes' of git://neil.brown.name/md:
        raid5: avoid finding "discard" stripe
        raid5: set bio bi_vcnt 0 for discard request
        md: avoid deadlock when md_set_badblocks.
        md: Fix skipping recovery for read-only arrays.
      e6036c0b
    • L
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · be6e8c76
      Linus Torvalds 提交于
      Pull SCSI fixes from James Bottomley:
       "This is a set of two fixes which cause oopses (Buslogic, qla2xxx) and
       one fix which may cause a hang because of request miscounting (sd)"
      
      * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
        [SCSI] sd: call blk_pm_runtime_init before add_disk
        [SCSI] qla2xxx: Fix request queue null dereference.
        [SCSI] BusLogic: Fix an oops when intializing multimaster adapter
      be6e8c76
    • V
      iser-target: check device before dereferencing its variable · 0a66614b
      Vu Pham 提交于
      This patch changes isert_connect_release() to correctly check for
      the existence struct isert_device *device before checking for
      isert_device->use_frwr.
      Signed-off-by: NVu Pham <vu@mellanox.com>
      Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>
      0a66614b
    • S
      raid5: avoid finding "discard" stripe · d47648fc
      Shaohua Li 提交于
      SCSI discard will damage discard stripe bio setting, eg, some fields are
      changed. If the stripe is reused very soon, we have wrong bios setting. We
      remove discard stripe from hash list, so next time the strip will be fully
      initialized.
      
      Suitable for backport to 3.7+.
      
      Cc: <stable@vger.kernel.org> (3.7+)
      Signed-off-by: NShaohua Li <shli@fusionio.com>
      Signed-off-by: NNeilBrown <neilb@suse.de>
      d47648fc
    • S
      raid5: set bio bi_vcnt 0 for discard request · 37c61ff3
      Shaohua Li 提交于
      SCSI layer will add new payload for discard request. If two bios are merged
      to one, the second bio has bi_vcnt 1 which is set in raid5. This will confuse
      SCSI and cause oops.
      
      Suitable for backport to 3.7+
      
      Cc: stable@vger.kernel.org (v3.7+)
      Reported-by: NJes Sorensen <Jes.Sorensen@redhat.com>
      Signed-off-by: NShaohua Li <shli@fusionio.com>
      Signed-off-by: NNeilBrown <neilb@suse.de>
      Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
      37c61ff3
    • B
      md: avoid deadlock when md_set_badblocks. · 905b0297
      Bian Yu 提交于
      When operate harddisk and hit errors, md_set_badblocks is called after
      scsi_restart_operations which already disabled the irq. but md_set_badblocks
      will call write_sequnlock_irq and enable irq. so softirq can preempt the
      current thread and that may cause a deadlock. I think this situation should
      use write_sequnlock_irqsave/irqrestore instead.
      
      I met the situation and the call trace is below:
      [  638.919974] BUG: spinlock recursion on CPU#0, scsi_eh_13/1010
      [  638.921923]  lock: 0xffff8800d4d51fc8, .magic: dead4ead, .owner: scsi_eh_13/1010, .owner_cpu: 0
      [  638.923890] CPU: 0 PID: 1010 Comm: scsi_eh_13 Not tainted 3.12.0-rc5+ #37
      [  638.925844] Hardware name: To be filled by O.E.M. To be filled by O.E.M./MAHOBAY, BIOS 4.6.5 03/05/2013
      [  638.927816]  ffff880037ad4640 ffff880118c03d50 ffffffff8172ff85 0000000000000007
      [  638.929829]  ffff8800d4d51fc8 ffff880118c03d70 ffffffff81730030 ffff8800d4d51fc8
      [  638.931848]  ffffffff81a72eb0 ffff880118c03d90 ffffffff81730056 ffff8800d4d51fc8
      [  638.933884] Call Trace:
      [  638.935867]  <IRQ>  [<ffffffff8172ff85>] dump_stack+0x55/0x76
      [  638.937878]  [<ffffffff81730030>] spin_dump+0x8a/0x8f
      [  638.939861]  [<ffffffff81730056>] spin_bug+0x21/0x26
      [  638.941836]  [<ffffffff81336de4>] do_raw_spin_lock+0xa4/0xc0
      [  638.943801]  [<ffffffff8173f036>] _raw_spin_lock+0x66/0x80
      [  638.945747]  [<ffffffff814a73ed>] ? scsi_device_unbusy+0x9d/0xd0
      [  638.947672]  [<ffffffff8173fb1b>] ? _raw_spin_unlock+0x2b/0x50
      [  638.949595]  [<ffffffff814a73ed>] scsi_device_unbusy+0x9d/0xd0
      [  638.951504]  [<ffffffff8149ec47>] scsi_finish_command+0x37/0xe0
      [  638.953388]  [<ffffffff814a75e8>] scsi_softirq_done+0xa8/0x140
      [  638.955248]  [<ffffffff8130e32b>] blk_done_softirq+0x7b/0x90
      [  638.957116]  [<ffffffff8104fddd>] __do_softirq+0xfd/0x330
      [  638.958987]  [<ffffffff810b964f>] ? __lock_release+0x6f/0x100
      [  638.960861]  [<ffffffff8174a5cc>] call_softirq+0x1c/0x30
      [  638.962724]  [<ffffffff81004c7d>] do_softirq+0x8d/0xc0
      [  638.964565]  [<ffffffff8105024e>] irq_exit+0x10e/0x150
      [  638.966390]  [<ffffffff8174ad4a>] smp_apic_timer_interrupt+0x4a/0x60
      [  638.968223]  [<ffffffff817499af>] apic_timer_interrupt+0x6f/0x80
      [  638.970079]  <EOI>  [<ffffffff810b964f>] ? __lock_release+0x6f/0x100
      [  638.971899]  [<ffffffff8173fa6a>] ? _raw_spin_unlock_irq+0x3a/0x50
      [  638.973691]  [<ffffffff8173fa60>] ? _raw_spin_unlock_irq+0x30/0x50
      [  638.975475]  [<ffffffff81562393>] md_set_badblocks+0x1f3/0x4a0
      [  638.977243]  [<ffffffff81566e07>] rdev_set_badblocks+0x27/0x80
      [  638.978988]  [<ffffffffa00d97bb>] raid5_end_read_request+0x36b/0x4e0 [raid456]
      [  638.980723]  [<ffffffff811b5a1d>] bio_endio+0x1d/0x40
      [  638.982463]  [<ffffffff81304ff3>] req_bio_endio.isra.65+0x83/0xa0
      [  638.984214]  [<ffffffff81306b9f>] blk_update_request+0x7f/0x350
      [  638.985967]  [<ffffffff81306ea1>] blk_update_bidi_request+0x31/0x90
      [  638.987710]  [<ffffffff813085e0>] __blk_end_bidi_request+0x20/0x50
      [  638.989439]  [<ffffffff8130862f>] __blk_end_request_all+0x1f/0x30
      [  638.991149]  [<ffffffff81308746>] blk_peek_request+0x106/0x250
      [  638.992861]  [<ffffffff814a62a9>] ? scsi_kill_request.isra.32+0xe9/0x130
      [  638.994561]  [<ffffffff814a633a>] scsi_request_fn+0x4a/0x3d0
      [  638.996251]  [<ffffffff813040a7>] __blk_run_queue+0x37/0x50
      [  638.997900]  [<ffffffff813045af>] blk_run_queue+0x2f/0x50
      [  638.999553]  [<ffffffff814a5750>] scsi_run_queue+0xe0/0x1c0
      [  639.001185]  [<ffffffff814a7721>] scsi_run_host_queues+0x21/0x40
      [  639.002798]  [<ffffffff814a2e87>] scsi_restart_operations+0x177/0x200
      [  639.004391]  [<ffffffff814a4fe9>] scsi_error_handler+0xc9/0xe0
      [  639.005996]  [<ffffffff814a4f20>] ? scsi_unjam_host+0xd0/0xd0
      [  639.007600]  [<ffffffff81072f6b>] kthread+0xdb/0xe0
      [  639.009205]  [<ffffffff81072e90>] ? flush_kthread_worker+0x170/0x170
      [  639.010821]  [<ffffffff81748cac>] ret_from_fork+0x7c/0xb0
      [  639.012437]  [<ffffffff81072e90>] ? flush_kthread_worker+0x170/0x170
      
      This bug was introduce in commit  2e8ac303
      (the first time rdev_set_badblock was call from interrupt context),
      so this patch is appropriate for 3.5 and subsequent kernels.
      
      Cc: <stable@vger.kernel.org> (3.5+)
      Signed-off-by: NBian Yu <bianyu@kedacom.com>
      Reviewed-by: NJianpeng Ma <majianpeng@gmail.com>
      Signed-off-by: NNeilBrown <neilb@suse.de>
      905b0297
    • L
      md: Fix skipping recovery for read-only arrays. · 61e4947c
      Lukasz Dorau 提交于
      Since:
              commit 7ceb17e8
              md: Allow devices to be re-added to a read-only array.
      
      spares are activated on a read-only array. In case of raid1 and raid10
      personalities it causes that not-in-sync devices are marked in-sync
      without checking if recovery has been finished.
      
      If a read-only array is degraded and one of its devices is not in-sync
      (because the array has been only partially recovered) recovery will be skipped.
      
      This patch adds checking if recovery has been finished before marking a device
      in-sync for raid1 and raid10 personalities. In case of raid5 personality
      such condition is already present (at raid5.c:6029).
      
      Bug was introduced in 3.10 and causes data corruption.
      
      Cc: stable@vger.kernel.org
      Signed-off-by: NPawel Baldysiak <pawel.baldysiak@intel.com>
      Signed-off-by: NLukasz Dorau <lukasz.dorau@intel.com>
      Signed-off-by: NNeilBrown <neilb@suse.de>
      61e4947c
    • D
      MAINTAINERS: add to ioatdma maintainer list · 18ebd564
      Dave Jiang 提交于
      Signed-off-by: NDave Jiang <dave.jiang@intel.com>
      [djbw: add dmaengine list]
      Signed-off-by: NDan Williams <dan.j.williams@intel.com>
      Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      18ebd564
    • V
      MAINTAINERS: add the new dmaengine mailing list · 17b59560
      Vinod Koul 提交于
      We have a new mailing list hosted by vger for dmaengine
      Acked-by: NDan Williams <dan.j.williams@intel.com>
      Signed-off-by: NVinod Koul <vinod.koul@intel.com>
      17b59560
  7. 23 10月, 2013 1 次提交
    • A
      [SCSI] sd: call blk_pm_runtime_init before add_disk · 10c580e4
      Aaron Lu 提交于
      Sujit has found a race condition that would make q->nr_pending
      unbalanced, it occurs as Sujit explained:
      
      "
      sd_probe_async() ->
      	add_disk() ->
      		disk_add_event() ->
      			schedule(disk_events_workfn)
      	sd_revalidate_disk()
      	blk_pm_runtime_init()
      return;
      
      Let's say the disk_events_workfn() calls sd_check_events() which tries
      to send test_unit_ready() and because of sd_revalidate_disk() trying to
      send another commands the test_unit_ready() might be re-queued as the
      tagged command queuing is disabled.
      
      So the race condition is -
      
      Thread 1 			  |		Thread 2
      sd_revalidate_disk()		  |	sd_check_events()
      ...nr_pending = 0 as q->dev = NULL|	scsi_queue_insert()
      blk_runtime_pm_init()		  | 	blk_pm_requeue_request() ->
      				  |	nr_pending = -1 since
      				  |	q->dev != NULL
      "
      
      The problem is, the test_unit_ready request doesn't get counted the
      first time it is queued, so the later decrement of q->nr_pending in
      blk_pm_requeue_request makes it unbalanced.
      
      Fix this by calling blk_pm_runtime_init before add_disk so that all
      requests initiated there will all be counted.
      Signed-off-by: NAaron Lu <aaron.lu@intel.com>
      Reported-and-tested-by: NSujit Reddy Thumma <sthumma@codeaurora.org>
      Cc: stable@vger.kernel.org
      Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>
      10c580e4