sr: check_events() ignore GET_EVENT when TUR says otherwise
commit 79b9677d885d1a792bc103f2febb06f91f92de43 upstream.
Some broken devices indicates that media has changed on every
GET_EVENT_STATUS_NOTIFICATION. This translates into MEDIA_CHANGE
uevent on every open() which lets udev run into a loop.
Verify GET_EVENT result against TUR and if it generates spurious
events for several times in a row, ignore the GET_EVENT events, and
trust only the TUR status.
This is the log of a USB stick with a (broken) fake CDROM drive:
scsi 5:0:0:0: Direct-Access SanDisk U3 Cruzer Micro 8.02 PQ: 0 ANSI: 0 CCS
sd 5:0:0:0: Attached scsi generic sg3 type 0
scsi 5:0:0:1: CD-ROM SanDisk U3 Cruzer Micro 8.02 PQ: 0 ANSI: 0
sd 5:0:0:0: [sdb] Attached SCSI removable disk
sr2: scsi3-mmc drive: 48x/48x tray
sr 5:0:0:1: Attached scsi CD-ROM sr2
sr 5:0:0:1: Attached scsi generic sg4 type 5
sr2: GET_EVENT and TUR disagree continuously, suppress GET_EVENT events
sd 5:0:0:0: [sdb] 31777279 512-byte logical blocks: (16.2 GB/15.1 GiB)
sd 5:0:0:0: [sdb] No Caching mode page present
sd 5:0:0:0: [sdb] Assuming drive cache: write through
sd 5:0:0:0: [sdb] No Caching mode page present
sd 5:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
-tj: Updated to consider only spurious GET_EVENT events among
different types of disagreement and allow using TUR for kernel
event polling after GET_EVENT is ignored.
Reported-By: Markus Rathgeb maggu2810@googlemail.com
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
index e036f1d..37c8f6b 100644
--- a/drivers/scsi/sr.h
+++ b/drivers/scsi/sr.h
@@ -41,6 +41,13 @@
unsigned readcd_known:1; /* drive supports READ_CD (0xbe) */
unsigned readcd_cdda:1; /* reading audio data using READ_CD */
unsigned media_present:1; /* media is present */
+
+ /* GET_EVENT spurious event handling, blk layer guarantees exclusion */
+ int tur_mismatch; /* nr of get_event TUR mismatches */
+ bool tur_changed:1; /* changed according to TUR */
+ bool get_event_changed:1; /* changed according to GET_EVENT */
+ bool ignore_get_event:1; /* GET_EVENT is unreliable, use TUR */
+
struct cdrom_device_info cdi;
/* We hold gendisk and scsi_device references on probe and use
* the refs on this kref to decide when to release them */