After lookup, that sdev is put opens the time window in which
subsequent operations on sdev are based upon no reliability until get
operation is issued.
The window is closed in this work by deferring the put operation until
necessary.
Signed-off-by: Hillf Danton <dhillf@xxxxxxxxx>
---
--- a/drivers/scsi/scsi_scan.c 2010-09-13 07:07:38.000000000 +0800
+++ b/drivers/scsi/scsi_scan.c 2010-11-06 19:23:30.000000000 +0800
@@ -1006,7 +1006,7 @@ static int scsi_probe_and_add_lun(struct
struct scsi_device **sdevp, int rescan,
void *hostdata)
{
- struct scsi_device *sdev;
+ struct scsi_device *sdev, *found;
unsigned char *result;
int bflags, res = SCSI_SCAN_NO_RESPONSE, result_len = 256;
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
@@ -1015,7 +1015,7 @@ static int scsi_probe_and_add_lun(struct
* The rescan flag is used as an optimization, the first scan of a
* host adapter calls into here with rescan == 0.
*/
- sdev = scsi_device_lookup_by_target(starget, lun);
+ found = sdev = scsi_device_lookup_by_target(starget, lun);
if (sdev) {
if (rescan || !scsi_device_created(sdev)) {
SCSI_LOG_SCAN_BUS(3, printk(KERN_INFO
@@ -1032,7 +1032,6 @@ static int scsi_probe_and_add_lun(struct
sdev->model);
return SCSI_SCAN_LUN_PRESENT;
}
- scsi_device_put(sdev);
} else
sdev = scsi_alloc_sdev(starget, lun, hostdata);
if (!sdev)
@@ -1125,15 +1124,22 @@ static int scsi_probe_and_add_lun(struct
out_free_sdev:
if (res == SCSI_SCAN_LUN_PRESENT) {
if (sdevp) {
- if (scsi_device_get(sdev) == 0) {
+ if (found)
+ *sdevp = found;
+ else if (scsi_device_get(sdev) == 0) {
*sdevp = sdev;
} else {
__scsi_remove_device(sdev);
res = SCSI_SCAN_NO_RESPONSE;
}
- }
- } else
- __scsi_remove_device(sdev);
+ } else if (found)
+ scsi_device_put(found);
+ } else {
+ if (found)
+ scsi_device_put(found);
+ else
+ __scsi_remove_device(sdev);
+ }
out:
return res;
}
--
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