Sorry, I sent an imcomplete patch. Here is the correct one.
BTW, The panic you saw is caused by the line (one of the lines you
added):
dev = container_of(&scsi_dh_data, struct scsi_device, scsi_dh_data);
in scsi_dh_release(). We cannot use pointer in a structure to get the
parent structure.
chandra
Keep a reference count of attaches, so that same number of detaches are allowed.
-----------
Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx>
---
Index: linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c
===================================================================
--- linux-2.6.27-rc8-git5.orig/drivers/scsi/device_handler/scsi_dh.c
+++ linux-2.6.27-rc8-git5/drivers/scsi/device_handler/scsi_dh.c
@@ -153,12 +153,28 @@ static int scsi_dh_handler_attach(struct
if (sdev->scsi_dh_data) {
if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
err = -EBUSY;
- } else if (scsi_dh->attach)
+ else
+ kref_get(&sdev->scsi_dh_data->kref);
+ } else if (scsi_dh->attach) {
err = scsi_dh->attach(sdev);
+ if (!err) {
+ kref_init(&sdev->scsi_dh_data->kref);
+ sdev->scsi_dh_data->sdev = sdev;
+ }
+ }
return err;
}
+static void scsi_dh_release(struct kref *kref)
+{
+ struct scsi_dh_data *scsi_dh_data;
+ scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
+
+ if (scsi_dh_data->scsi_dh && scsi_dh_data->scsi_dh->detach)
+ scsi_dh_data->scsi_dh->detach(scsi_dh_data->sdev);
+}
+
/*
* scsi_dh_handler_detach - Detach a device handler from a device
* @sdev - SCSI device the device handler should be detached from
@@ -176,11 +192,7 @@ static void scsi_dh_handler_detach(struc
if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
return;
- if (!scsi_dh)
- scsi_dh = sdev->scsi_dh_data->scsi_dh;
-
- if (scsi_dh && scsi_dh->detach)
- scsi_dh->detach(sdev);
+ kref_put(&sdev->scsi_dh_data->kref, scsi_dh_release);
}
/*
Index: linux-2.6.27-rc8-git5/include/scsi/scsi_device.h
===================================================================
--- linux-2.6.27-rc8-git5.orig/include/scsi/scsi_device.h
+++ linux-2.6.27-rc8-git5/include/scsi/scsi_device.h
@@ -6,6 +6,7 @@
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/blkdev.h>
+#include <linux/kref.h>
#include <scsi/scsi.h>
#include <asm/atomic.h>
@@ -191,6 +192,8 @@ struct scsi_device_handler {
struct scsi_dh_data {
struct scsi_device_handler *scsi_dh;
+ struct kref kref;
+ struct scsi_device *sdev; /* back reference */
char buf[0];
};
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