| Message ID | 20220303075527.25258-2-alice.chao@mediatek.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/1] scsi: Fix racing between dev init and dev reset | expand |
Hi Alice, > Device reset thread uses kobject_uevent_env() to get kobj.parent > after scsi_evt_emit(), and it races with device init thread which > calls device_add() to create kobj.parent before kobject_uevent_env(). > > Device reset call trace: > fill_kobj_path > kobject_get_path > kobject_uevent_env > scsi_evt_emit <- add wait_event() > scsi_evt_thread > > Device init call trace: > fill_kobj_path > kobject_get_path > kobject_uevent_env > device_add <- create kobj.parent > scsi_target_add > scsi_sysfs_add_sdev > scsi_add_lun > scsi_probe_and_add_lun > > These two jobs are scheduled asynchronously, we can't guaranteed that > kobj.parent will be created in device init thread before device reset > thread calls kobj_get_path(). > > To resolve the racing issue between device init thread and device > reset thread, we use wait_event() in scsi_evt_emit() to wait for > device_add() to complete the creation of kobj.parent. > > Signed-off-by: Alice Chao <alice.chao@mediatek.com> > Change-Id: I2848cf054186739d3a125a0635dbed5539557e64 please remove Change-Id here thanks, Miles
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 0a70aa763a96..abf9a71ed77c 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -2461,6 +2461,7 @@ static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) break; case SDEV_EVT_POWER_ON_RESET_OCCURRED: envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED"; + wait_event(sdev->host->host_wait, sdev->sdev_gendev.kobj.parent != NULL); break; default: /* do nothing */ diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index f4e6c68ac99e..431f229ac435 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1904,6 +1904,7 @@ static void do_scsi_scan_host(struct Scsi_Host *shost) } else { scsi_scan_host_selected(shost, SCAN_WILD_CARD, SCAN_WILD_CARD, SCAN_WILD_CARD, 0); + wake_up(&shost->host_wait); } }
Device reset thread uses kobject_uevent_env() to get kobj.parent after scsi_evt_emit(), and it races with device init thread which calls device_add() to create kobj.parent before kobject_uevent_env(). Device reset call trace: fill_kobj_path kobject_get_path kobject_uevent_env scsi_evt_emit <- add wait_event() scsi_evt_thread Device init call trace: fill_kobj_path kobject_get_path kobject_uevent_env device_add <- create kobj.parent scsi_target_add scsi_sysfs_add_sdev scsi_add_lun scsi_probe_and_add_lun These two jobs are scheduled asynchronously, we can't guaranteed that kobj.parent will be created in device init thread before device reset thread calls kobj_get_path(). To resolve the racing issue between device init thread and device reset thread, we use wait_event() in scsi_evt_emit() to wait for device_add() to complete the creation of kobj.parent. Signed-off-by: Alice Chao <alice.chao@mediatek.com> Change-Id: I2848cf054186739d3a125a0635dbed5539557e64 --- drivers/scsi/scsi_lib.c | 1 + drivers/scsi/scsi_scan.c | 1 + 2 files changed, 2 insertions(+)