1 files changed, 42 insertions, 4 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 4778e2707168..5fc97d2ba2fd 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -221,14 +221,33 @@ static unsigned int sr_check_events(struct cdrom_device_info *cdi,
                 return 0;
 
         events = sr_get_events(cd->device);
+        cd->get_event_changed |= events & DISK_EVENT_MEDIA_CHANGE;
+
+        /*
+         * If earlier GET_EVENT_STATUS_NOTIFICATION and TUR did not agree
+         * for several times in a row.  We rely on TUR only for this likely
+         * broken device, to prevent generating incorrect media changed
+         * events for every open().
+         */
+        if (cd->ignore_get_event) {
+                events &= ~DISK_EVENT_MEDIA_CHANGE;
+                goto do_tur;
+        }
+
         /*
          * GET_EVENT_STATUS_NOTIFICATION is enough unless MEDIA_CHANGE
          * is being cleared.  Note that there are devices which hang
          * if asked to execute TUR repeatedly.
          */
-        if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
-                goto skip_tur;
+        if (cd->device->changed) {
+                events |= DISK_EVENT_MEDIA_CHANGE;
+                cd->device->changed = 0;
+                cd->tur_changed = true;
+        }
 
+        if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
+                return events;
+do_tur:
         /* let's see whether the media is there with TUR */
         last_present = cd->media_present;
         ret = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
@@ -242,12 +261,31 @@ static unsigned int sr_check_events(struct cdrom_device_info *cdi,
                 (scsi_sense_valid(&sshdr) && sshdr.asc != 0x3a);
 
         if (last_present != cd->media_present)
-                events |= DISK_EVENT_MEDIA_CHANGE;
-skip_tur:
+                cd->device->changed = 1;
+
         if (cd->device->changed) {
                 events |= DISK_EVENT_MEDIA_CHANGE;
                 cd->device->changed = 0;
+                cd->tur_changed = true;
+        }
+
+        if (cd->ignore_get_event)
+                return events;
+
+        /* check whether GET_EVENT is reporting spurious MEDIA_CHANGE */
+        if (!cd->tur_changed) {
+                if (cd->get_event_changed) {
+                        if (cd->tur_mismatch++ > 8) {
+                                sdev_printk(KERN_WARNING, cd->device,
+                                            "GET_EVENT and TUR disagree continuously, suppress GET_EVENT events\n");
+                                cd->ignore_get_event = true;
+                        }
+                } else {
+                        cd->tur_mismatch = 0;
+                }
         }
+        cd->tur_changed = false;
+        cd->get_event_changed = false;
 
         return events;
 }