lkml.org 
[lkml]   [2017]   [Jul]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.12 044/196] scsi: Add STARGET_CREATED_REMOVE state to scsi_target_state
    Date
    4.12-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ewan D. Milne <emilne@redhat.com>

    commit f9279c968c257ee39b0d7bd2571a4d231a67bcc1 upstream.

    The addition of the STARGET_REMOVE state had the side effect of
    introducing a race condition that can cause a crash.

    scsi_target_reap_ref_release() checks the starget->state to
    see if it still in STARGET_CREATED, and if so, skips calling
    transport_remove_device() and device_del(), because the starget->state
    is only set to STARGET_RUNNING after scsi_target_add() has called
    device_add() and transport_add_device().

    However, if an rport loss occurs while a target is being scanned,
    it can happen that scsi_remove_target() will be called while the
    starget is still in the STARGET_CREATED state. In this case, the
    starget->state will be set to STARGET_REMOVE, and as a result,
    scsi_target_reap_ref_release() will take the wrong path. The end
    result is a panic:

    [ 1255.356653] Oops: 0000 [#1] SMP
    [ 1255.360154] Modules linked in: x86_pkg_temp_thermal kvm_intel kvm irqbypass crc32c_intel ghash_clmulni_i
    [ 1255.393234] CPU: 5 PID: 149 Comm: kworker/u96:4 Tainted: G W 4.11.0+ #8
    [ 1255.401879] Hardware name: Dell Inc. PowerEdge R320/08VT7V, BIOS 2.0.22 11/19/2013
    [ 1255.410327] Workqueue: scsi_wq_6 fc_scsi_scan_rport [scsi_transport_fc]
    [ 1255.417720] task: ffff88060ca8c8c0 task.stack: ffffc900048a8000
    [ 1255.424331] RIP: 0010:kernfs_find_ns+0x13/0xc0
    [ 1255.429287] RSP: 0018:ffffc900048abbf0 EFLAGS: 00010246
    [ 1255.435123] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
    [ 1255.443083] RDX: 0000000000000000 RSI: ffffffff8188d659 RDI: 0000000000000000
    [ 1255.451043] RBP: ffffc900048abc10 R08: 0000000000000000 R09: 0000012433fe0025
    [ 1255.459005] R10: 0000000025e5a4b5 R11: 0000000025e5a4b5 R12: ffffffff8188d659
    [ 1255.466972] R13: 0000000000000000 R14: ffff8805f55e5088 R15: 0000000000000000
    [ 1255.474931] FS: 0000000000000000(0000) GS:ffff880616b40000(0000) knlGS:0000000000000000
    [ 1255.483959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [ 1255.490370] CR2: 0000000000000068 CR3: 0000000001c09000 CR4: 00000000000406e0
    [ 1255.498332] Call Trace:
    [ 1255.501058] kernfs_find_and_get_ns+0x31/0x60
    [ 1255.505916] sysfs_unmerge_group+0x1d/0x60
    [ 1255.510498] dpm_sysfs_remove+0x22/0x60
    [ 1255.514783] device_del+0xf4/0x2e0
    [ 1255.518577] ? device_remove_file+0x19/0x20
    [ 1255.523241] attribute_container_class_device_del+0x1a/0x20
    [ 1255.529457] transport_remove_classdev+0x4e/0x60
    [ 1255.534607] ? transport_add_class_device+0x40/0x40
    [ 1255.540046] attribute_container_device_trigger+0xb0/0xc0
    [ 1255.546069] transport_remove_device+0x15/0x20
    [ 1255.551025] scsi_target_reap_ref_release+0x25/0x40
    [ 1255.556467] scsi_target_reap+0x2e/0x40
    [ 1255.560744] __scsi_scan_target+0xaa/0x5b0
    [ 1255.565312] scsi_scan_target+0xec/0x100
    [ 1255.569689] fc_scsi_scan_rport+0xb1/0xc0 [scsi_transport_fc]
    [ 1255.576099] process_one_work+0x14b/0x390
    [ 1255.580569] worker_thread+0x4b/0x390
    [ 1255.584651] kthread+0x109/0x140
    [ 1255.588251] ? rescuer_thread+0x330/0x330
    [ 1255.592730] ? kthread_park+0x60/0x60
    [ 1255.596815] ret_from_fork+0x29/0x40
    [ 1255.600801] Code: 24 08 48 83 42 40 01 5b 41 5c 5d c3 66 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 66 66 90
    [ 1255.621876] RIP: kernfs_find_ns+0x13/0xc0 RSP: ffffc900048abbf0
    [ 1255.628479] CR2: 0000000000000068
    [ 1255.632756] ---[ end trace 34a69ba0477d036f ]---

    Fix this by adding another scsi_target state STARGET_CREATED_REMOVE
    to distinguish this case.

    Fixes: f05795d3d771 ("scsi: Add intermediate STARGET_REMOVE state to scsi_target_state")
    Reported-by: David Jeffery <djeffery@redhat.com>
    Signed-off-by: Ewan D. Milne <emilne@redhat.com>
    Reviewed-by: Laurence Oberman <loberman@redhat.com>
    Tested-by: Laurence Oberman <loberman@redhat.com>
    Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/scsi/scsi_scan.c | 5 +++--
    drivers/scsi/scsi_sysfs.c | 8 ++++++--
    include/scsi/scsi_device.h | 1 +
    3 files changed, 10 insertions(+), 4 deletions(-)

    --- a/drivers/scsi/scsi_scan.c
    +++ b/drivers/scsi/scsi_scan.c
    @@ -384,11 +384,12 @@ static void scsi_target_reap_ref_release
    = container_of(kref, struct scsi_target, reap_ref);

    /*
    - * if we get here and the target is still in the CREATED state that
    + * if we get here and the target is still in a CREATED state that
    * means it was allocated but never made visible (because a scan
    * turned up no LUNs), so don't call device_del() on it.
    */
    - if (starget->state != STARGET_CREATED) {
    + if ((starget->state != STARGET_CREATED) &&
    + (starget->state != STARGET_CREATED_REMOVE)) {
    transport_remove_device(&starget->dev);
    device_del(&starget->dev);
    }
    --- a/drivers/scsi/scsi_sysfs.c
    +++ b/drivers/scsi/scsi_sysfs.c
    @@ -1370,11 +1370,15 @@ restart:
    spin_lock_irqsave(shost->host_lock, flags);
    list_for_each_entry(starget, &shost->__targets, siblings) {
    if (starget->state == STARGET_DEL ||
    - starget->state == STARGET_REMOVE)
    + starget->state == STARGET_REMOVE ||
    + starget->state == STARGET_CREATED_REMOVE)
    continue;
    if (starget->dev.parent == dev || &starget->dev == dev) {
    kref_get(&starget->reap_ref);
    - starget->state = STARGET_REMOVE;
    + if (starget->state == STARGET_CREATED)
    + starget->state = STARGET_CREATED_REMOVE;
    + else
    + starget->state = STARGET_REMOVE;
    spin_unlock_irqrestore(shost->host_lock, flags);
    __scsi_remove_target(starget);
    scsi_target_reap(starget);
    --- a/include/scsi/scsi_device.h
    +++ b/include/scsi/scsi_device.h
    @@ -248,6 +248,7 @@ enum scsi_target_state {
    STARGET_CREATED = 1,
    STARGET_RUNNING,
    STARGET_REMOVE,
    + STARGET_CREATED_REMOVE,
    STARGET_DEL,
    };


    \
     
     \ /
      Last update: 2017-07-25 22:05    [W:4.171 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site