scsi: sr: Avoid that opening a CD-ROM hangs with runtime power management enabled

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>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
[bwh: Backported to 3.16:
 - Update one extra "goto out" in sr_block_ioctl() and delete the unused
   label
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 8ebe3a732e6d9e66ffa263cacccfca8c92131a45..980b45d8f16e76e852376d092d213fc5d00050f1 100644 (file)
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -521,16 +521,25 @@ static int sr_init_command(struct scsi_cmnd *SCpnt)
 static int sr_block_open(struct block_device *bdev, fmode_t mode)
 {
        struct scsi_cd *cd;
+       struct scsi_device *sdev;
        int ret = -ENXIO;
 
-       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);
-       }
+       if (!cd)
+               goto out;
+
+       sdev = cd->device;
+       scsi_autopm_get_device(sdev);
+
+       mutex_lock(&sr_mutex);
+       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;
 }
 
@@ -553,6 +562,8 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
 
        mutex_lock(&sr_mutex);
 
+       scsi_autopm_get_device(sdev);
+
        /*
         * Send SCSI addressing ioctls directly to mid level, send other
         * ioctls to cdrom/block level.
@@ -561,12 +572,12 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
        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;
 
        /*
         * ENODEV means that we didn't recognise the ioctl, or that we
@@ -577,10 +588,12 @@ static int sr_block_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
        ret = scsi_nonblockable_ioctl(sdev, cmd, argp,
                                        (mode & FMODE_NDELAY) != 0);
        if (ret != -ENODEV)
-               goto out;
+               goto put;
        ret = scsi_ioctl(sdev, cmd, argp);
 
-out:
+put:
+       scsi_autopm_put_device(sdev);
+
        mutex_unlock(&sr_mutex);
        return ret;
 }