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Message-Id: <20240605091731.3111195-2-haowenchao22@gmail.com>
Date: Wed, 5 Jun 2024 17:17:29 +0800
From: Wenchao Hao <haowenchao22@...il.com>
To: "James E . J . Bottomley" <James.Bottomley@...senPartnership.com>,
"Martin K . Petersen" <martin.petersen@...cle.com>,
linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Wenchao Hao <haowenchao22@...il.com>
Subject: [PATCH v5 1/3] scsi: core: Add new helper to iterate all devices of host
shost_for_each_device() would skip devices which is in SDEV_CANCEL or
SDEV_DEL state, for some scenarios, we donot want to skip these devices,
so add a new macro shost_for_each_device_include_deleted() to handle it.
Following changes are introduced:
1. Rework scsi_device_get(), add new helper __scsi_device_get() which
determine if skip deleted scsi_device by parameter "skip_deleted".
2. Add new parameter "skip_deleted" to __scsi_iterate_devices() which
is used when calling __scsi_device_get()
3. Update shost_for_each_device() to call __scsi_iterate_devices() with
"skip_deleted" true
4. Add new macro shost_for_each_device_include_deleted() which call
__scsi_iterate_devices() with "skip_deleted" false
Signed-off-by: Wenchao Hao <haowenchao22@...il.com>
---
drivers/scsi/scsi.c | 46 ++++++++++++++++++++++++++------------
include/scsi/scsi_device.h | 25 ++++++++++++++++++---
2 files changed, 54 insertions(+), 17 deletions(-)
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 3e0c0381277a..5913de543d93 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -735,20 +735,18 @@ int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
return 0;
}
-/**
- * scsi_device_get - get an additional reference to a scsi_device
+/*
+ * __scsi_device_get - get an additional reference to a scsi_device
* @sdev: device to get a reference to
- *
- * 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.
+ * @skip_deleted: when true, would return failed if device is deleted
*/
-int scsi_device_get(struct scsi_device *sdev)
+static int __scsi_device_get(struct scsi_device *sdev, bool skip_deleted)
{
- if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
+ /*
+ * if skip_deleted is true and device is in removing, return failed
+ */
+ if (skip_deleted &&
+ (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL))
goto fail;
if (!try_module_get(sdev->host->hostt->module))
goto fail;
@@ -761,6 +759,22 @@ int scsi_device_get(struct scsi_device *sdev)
fail:
return -ENXIO;
}
+
+/**
+ * scsi_device_get - get an additional reference to a scsi_device
+ * @sdev: device to get a reference to
+ *
+ * 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)
+{
+ return __scsi_device_get(sdev, 0);
+}
EXPORT_SYMBOL(scsi_device_get);
/**
@@ -780,9 +794,13 @@ void scsi_device_put(struct scsi_device *sdev)
}
EXPORT_SYMBOL(scsi_device_put);
-/* helper for shost_for_each_device, see that for documentation */
+/**
+ * helper for shost_for_each_device, see that for documentation
+ * @skip_deleted: if true, sdev in progress of removing would be skipped
+ */
struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
- struct scsi_device *prev)
+ struct scsi_device *prev,
+ bool skip_deleted)
{
struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
struct scsi_device *next = NULL;
@@ -792,7 +810,7 @@ struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
while (list->next != &shost->__devices) {
next = list_entry(list->next, struct scsi_device, siblings);
/* skip devices that we can't get a reference to */
- if (!scsi_device_get(next))
+ if (!__scsi_device_get(next, skip_deleted))
break;
next = NULL;
list = list->next;
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 9c540f5468eb..5cb294ff0a41 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -412,7 +412,8 @@ extern void __starget_for_each_device(struct scsi_target *, void *,
/* only exposed to implement shost_for_each_device */
extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,
- struct scsi_device *);
+ struct scsi_device *,
+ bool);
/**
* shost_for_each_device - iterate over all devices of a host
@@ -422,11 +423,29 @@ extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,
* Iterator that returns each device attached to @shost. This loop
* takes a reference on each device and releases it at the end. If
* you break out of the loop, you must call scsi_device_put(sdev).
+ *
+ * Note: this macro would skip sdev which is in progress of removing
*/
#define shost_for_each_device(sdev, shost) \
- for ((sdev) = __scsi_iterate_devices((shost), NULL); \
+ for ((sdev) = __scsi_iterate_devices((shost), NULL, 1); \
+ (sdev); \
+ (sdev) = __scsi_iterate_devices((shost), (sdev), 1))
+
+/*
+ * shost_for_each_device_include_deleted- iterate over all devices of a host
+ * @sdev: the &struct scsi_device to use as a cursor
+ * @shost: the &struct scsi_host to iterate over
+ *
+ * Iterator that returns each device attached to @shost. This loop
+ * takes a reference on each device and releases it at the end. If
+ * you break out of the loop, you must call scsi_device_put(sdev).
+ *
+ * Note: this macro would include sdev which is in progress of removing
+ */
+#define shost_for_each_device_include_deleted(sdev, shost) \
+ for ((sdev) = __scsi_iterate_devices((shost), NULL, 0); \
(sdev); \
- (sdev) = __scsi_iterate_devices((shost), (sdev)))
+ (sdev) = __scsi_iterate_devices((shost), (sdev), 0))
/**
* __shost_for_each_device - iterate over all devices of a host (UNLOCKED)
--
2.38.1
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