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linux-next/drivers/scsi/sr.h
Kay Sievers 79b9677d88 [SCSI] sr: check_events() ignore GET_EVENT when TUR says otherwise
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>
Cc: stable@kernel.org	# >= v2.6.38, fixes udev busy looping w/ certain devices
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2011-07-21 14:15:58 -07:00

78 lines
2.5 KiB
C

/*
* sr.h by David Giller
* CD-ROM disk driver header file
*
* adapted from:
* sd.h Copyright (C) 1992 Drew Eckhardt
* SCSI disk driver header file by
* Drew Eckhardt
*
* <drew@colorado.edu>
*
* Modified by Eric Youngdale eric@andante.org to
* add scatter-gather, multiple outstanding request, and other
* enhancements.
*/
#ifndef _SR_H
#define _SR_H
#include <linux/genhd.h>
#include <linux/kref.h>
#define MAX_RETRIES 3
#define SR_TIMEOUT (30 * HZ)
struct scsi_device;
/* The CDROM is fairly slow, so we need a little extra time */
/* In fact, it is very slow if it has to spin up first */
#define IOCTL_TIMEOUT 30*HZ
typedef struct scsi_cd {
struct scsi_driver *driver;
unsigned capacity; /* size in blocks */
struct scsi_device *device;
unsigned int vendor; /* vendor code, see sr_vendor.c */
unsigned long ms_offset; /* for reading multisession-CD's */
unsigned use:1; /* is this device still supportable */
unsigned xa_flag:1; /* CD has XA sectors ? */
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 */
struct kref kref;
struct gendisk *disk;
} Scsi_CD;
int sr_do_ioctl(Scsi_CD *, struct packet_command *);
int sr_lock_door(struct cdrom_device_info *, int);
int sr_tray_move(struct cdrom_device_info *, int);
int sr_drive_status(struct cdrom_device_info *, int);
int sr_disk_status(struct cdrom_device_info *);
int sr_get_last_session(struct cdrom_device_info *, struct cdrom_multisession *);
int sr_get_mcn(struct cdrom_device_info *, struct cdrom_mcn *);
int sr_reset(struct cdrom_device_info *);
int sr_select_speed(struct cdrom_device_info *cdi, int speed);
int sr_audio_ioctl(struct cdrom_device_info *, unsigned int, void *);
int sr_is_xa(Scsi_CD *);
/* sr_vendor.c */
void sr_vendor_init(Scsi_CD *);
int sr_cd_check(struct cdrom_device_info *);
int sr_set_blocklength(Scsi_CD *, int blocklength);
#endif