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    Subject[PATCH 4.14 010/104] scsi: sr: Avoid that opening a CD-ROM hangs with runtime power management enabled
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: Bart Van Assche <bart.vanassche@wdc.com>

    commit 1214fd7b497400d200e3f4e64e2338b303a20949 upstream.

    Surround scsi_execute() calls with scsi_autopm_get_device() and
    scsi_autopm_put_device(). Note: removing sr_mutex protection from the
    scsi_cd_get() and scsi_cd_put() calls is safe because the purpose of
    sr_mutex is to serialize cdrom_*() calls.

    This patch avoids that complaints similar to the following appear in the
    kernel log if runtime power management is enabled:

    INFO: task systemd-udevd:650 blocked for more than 120 seconds.
    Not tainted 4.18.0-rc7-dbg+ #1
    "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
    systemd-udevd D28176 650 513 0x00000104
    Call Trace:
    __schedule+0x444/0xfe0
    schedule+0x4e/0xe0
    schedule_preempt_disabled+0x18/0x30
    __mutex_lock+0x41c/0xc70
    mutex_lock_nested+0x1b/0x20
    __blkdev_get+0x106/0x970
    blkdev_get+0x22c/0x5a0
    blkdev_open+0xe9/0x100
    do_dentry_open.isra.19+0x33e/0x570
    vfs_open+0x7c/0xd0
    path_openat+0x6e3/0x1120
    do_filp_open+0x11c/0x1c0
    do_sys_open+0x208/0x2d0
    __x64_sys_openat+0x59/0x70
    do_syscall_64+0x77/0x230
    entry_SYSCALL_64_after_hwframe+0x49/0xbe

    Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
    Cc: Maurizio Lombardi <mlombard@redhat.com>
    Cc: Johannes Thumshirn <jthumshirn@suse.de>
    Cc: Alan Stern <stern@rowland.harvard.edu>
    Cc: <stable@vger.kernel.org>
    Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
    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/sr.c | 29 +++++++++++++++++++++--------
    1 file changed, 21 insertions(+), 8 deletions(-)

    --- a/drivers/scsi/sr.c
    +++ b/drivers/scsi/sr.c
    @@ -523,18 +523,26 @@ static int sr_init_command(struct scsi_c
    static int sr_block_open(struct block_device *bdev, fmode_t mode)
    {
    struct scsi_cd *cd;
    + struct scsi_device *sdev;
    int ret = -ENXIO;

    + cd = scsi_cd_get(bdev->bd_disk);
    + if (!cd)
    + goto out;
    +
    + sdev = cd->device;
    + scsi_autopm_get_device(sdev);
    check_disk_change(bdev);

    mutex_lock(&sr_mutex);
    - cd = scsi_cd_get(bdev->bd_disk);
    - if (cd) {
    - ret = cdrom_open(&cd->cdi, bdev, mode);
    - if (ret)
    - scsi_cd_put(cd);
    - }
    + ret = cdrom_open(&cd->cdi, bdev, mode);
    mutex_unlock(&sr_mutex);
    +
    + scsi_autopm_put_device(sdev);
    + if (ret)
    + scsi_cd_put(cd);
    +
    +out:
    return ret;
    }

    @@ -562,6 +570,8 @@ static int sr_block_ioctl(struct block_d
    if (ret)
    goto out;

    + scsi_autopm_get_device(sdev);
    +
    /*
    * Send SCSI addressing ioctls directly to mid level, send other
    * ioctls to cdrom/block level.
    @@ -570,15 +580,18 @@ static int sr_block_ioctl(struct block_d
    case SCSI_IOCTL_GET_IDLUN:
    case SCSI_IOCTL_GET_BUS_NUMBER:
    ret = scsi_ioctl(sdev, cmd, argp);
    - goto out;
    + goto put;
    }

    ret = cdrom_ioctl(&cd->cdi, bdev, mode, cmd, arg);
    if (ret != -ENOSYS)
    - goto out;
    + goto put;

    ret = scsi_ioctl(sdev, cmd, argp);

    +put:
    + scsi_autopm_put_device(sdev);
    +
    out:
    mutex_unlock(&sr_mutex);
    return ret;

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