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authorChandra Seetharaman <sekharan@us.ibm.com>2009-06-26 19:30:06 -0700
committerJames Bottomley <James.Bottomley@suse.de>2009-08-22 17:51:51 -0500
commit6c10db72c94818573552fd71c89540da325efdfb (patch)
tree6afa9b0431d22638a1a11dfe3c5924b8e1a8e2f3
parentb4567ca6304a9b31cb2eae62f812e9eb9badcb60 (diff)
[SCSI] scsi_dh: Reference count scsi_dh_attach
Problem reported: http://marc.info/?l=dm-devel&m=124585978305866&w=2 scsi_dh does not do a refernce count for attach/detach, and this affects the way it is supposed to work with multipath when a device is not in the dev_list of the hardware handler. This patch adds a reference count that counts each attach. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
-rw-r--r--drivers/scsi/device_handler/scsi_dh.c23
-rw-r--r--include/scsi/scsi_device.h2
2 files changed, 18 insertions, 7 deletions
diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index a518f2eff19..53a7385e1b4 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -153,12 +153,24 @@ static int scsi_dh_handler_attach(struct scsi_device *sdev,
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 __detach_handler (struct kref *kref)
+{
+ struct scsi_dh_data *scsi_dh_data = container_of(kref, struct scsi_dh_data, kref);
+ 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
@@ -180,7 +192,7 @@ static void scsi_dh_handler_detach(struct scsi_device *sdev,
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, __detach_handler);
}
/*
@@ -474,7 +486,6 @@ int scsi_dh_attach(struct request_queue *q, const char *name)
if (!err) {
err = scsi_dh_handler_attach(sdev, scsi_dh);
-
put_device(&sdev->sdev_gendev);
}
return err;
@@ -505,10 +516,8 @@ void scsi_dh_detach(struct request_queue *q)
return;
if (sdev->scsi_dh_data) {
- /* if sdev is not on internal list, detach */
scsi_dh = sdev->scsi_dh_data->scsi_dh;
- if (!device_handler_match(scsi_dh, sdev))
- scsi_dh_handler_detach(sdev, scsi_dh);
+ scsi_dh_handler_detach(sdev, scsi_dh);
}
put_device(&sdev->sdev_gendev);
}
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 3f566af3f10..1f3a4c8044c 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -191,6 +191,8 @@ struct scsi_device_handler {
struct scsi_dh_data {
struct scsi_device_handler *scsi_dh;
+ struct scsi_device *sdev;
+ struct kref kref;
char buf[0];
};