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authorChristoph Hellwig <hch@lst.de>2015-02-02 14:01:26 +0100
committerJames Bottomley <JBottomley@Parallels.com>2015-03-19 06:43:15 -0700
commitcff549e4860fcdea6b22510defdc8c8a0f82455a (patch)
tree62b1d3e75ba06f46593883beb0ef48ac684907a3
parent3d9a1f530e508ff6fc9ab8220016b02f1bce255b (diff)
scsi: proper state checking and module refcount handling in scsi_device_get
This effectively reverts commits 85b6c7 ("[SCSI] sd: fix cache flushing on module removal (and individual device removal)" and dc4515ea ("scsi: always increment reference count"). We now never call scsi_device_get from the shutdown path, and the fact that we started grabbing reference there in commit 85b6c7 turned out turned out to create more problems than it solves, and required workarounds for workarounds for workarounds. Move back to properly checking the device state and carefully handle module refcounting. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
-rw-r--r--drivers/scsi/scsi.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index c9c3b579eece..3833bf59fb66 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -972,18 +972,24 @@ EXPORT_SYMBOL(scsi_report_opcode);
* Description: Gets a reference to the scsi_device and increments the use count
* of the underlying LLDD module. You must hold host_lock of the
* parent Scsi_Host or already have a reference when calling this.
+ *
+ * This will fail if a device is deleted or cancelled, or when the LLD module
+ * is in the process of being unloaded.
*/
int scsi_device_get(struct scsi_device *sdev)
{
- if (sdev->sdev_state == SDEV_DEL)
- return -ENXIO;
+ if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
+ goto fail;
if (!get_device(&sdev->sdev_gendev))
- return -ENXIO;
- /* We can fail try_module_get if we're doing SCSI operations
- * from module exit (like cache flush) */
- __module_get(sdev->host->hostt->module);
-
+ goto fail;
+ if (!try_module_get(sdev->host->hostt->module))
+ goto fail_put_device;
return 0;
+
+fail_put_device:
+ put_device(&sdev->sdev_gendev);
+fail:
+ return -ENXIO;
}
EXPORT_SYMBOL(scsi_device_get);