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

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>

1 files changed, 21 insertions, 8 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 3f3cb72e0c0c..d0389b20574d 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -523,18 +523,26 @@ 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;
 
+        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_device *bdev, fmode_t mode, unsigned cmd,
         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_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;
 
         ret = scsi_ioctl(sdev, cmd, argp);
 
+put:
+        scsi_autopm_put_device(sdev);
+
 out:
         mutex_unlock(&sr_mutex);
         return ret;