Re: [PATCH v7 5/9] Disallow changing the device state via sysfs into "deleted"

[Bart Van Assche <bvanassche@acm.org>]

On 12/07/12 13:46, Bart Van Assche wrote:
> On 12/07/12 07:55, Hannes Reinecke wrote:
>> On 12/06/2012 04:56 PM, Bart Van Assche wrote:
>>> Changing the state of a SCSI device via sysfs into "cancel" or
>>> "deleted" prevents scsi_remove_host() to remove these devices.
>>> Hence do not allow this.
>>>
>>> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
>>> Cc: Tejun Heo <tj@kernel.org>
>>> Cc: James Bottomley <JBottomley@Parallels.com>
>>> Cc: Mike Christie <michaelc@cs.wisc.edu>
>>> Cc: Hannes Reinecke <hare@suse.de>
>>> ---
>>>   drivers/scsi/scsi_sysfs.c |    7 +++++--
>>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
>>> index 4348f12..b319c20 100644
>>> --- a/drivers/scsi/scsi_sysfs.c
>>> +++ b/drivers/scsi/scsi_sysfs.c
>>> @@ -591,13 +591,15 @@ sdev_store_delete(struct device *dev, struct
>>> device_attribute *attr,
>>>   };
>>>   static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
>>>
>>> +#define INVALID_SDEV_STATE 0
>>> +
>> Shouldn't this become part of the enum?
>> Defining it outside only confuses the compiler.
>> And the unsuspecting user.
> 
> I can do that, but that will require changes in every switch statement 
> on enum scsi_device_state because the kernel code is compiled with 
> -Wswitch. From the gcc manual: <quote>-Wswitch: Warn whenever a switch 
> statement has an index of enumerated type and lacks a case for one or 
> more of the named codes of that enumeration. (The presence of a default 
> label prevents this warning.)</quote>

(replying to my own e-mail)

Apparently there is only one such switch statement that has to be
updated. The add-on patch below realizes the above proposal:

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index d80714f..253fc30 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2158,6 +2158,8 @@ scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
 		}
 		break;
 
+	case INVALID_SDEV_STATE:
+		goto illegal;
 	}
 	sdev->sdev_state = state;
 	return 0;
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 3293ba7..81d9d55 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -592,8 +592,6 @@ sdev_store_delete(struct device *dev, struct device_attribute *attr,
 };
 static DEVICE_ATTR(delete, S_IWUSR, NULL, sdev_store_delete);
 
-#define INVALID_SDEV_STATE 0
-
 static ssize_t
 store_state_field(struct device *dev, struct device_attribute *attr,
 		  const char *buf, size_t count)
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 83a6532..4281ff4 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -29,7 +29,11 @@ struct scsi_mode_data {
  * scsi_lib:scsi_device_set_state().
  */
 enum scsi_device_state {
-	SDEV_CREATED = 1,	/* device created but not added to sysfs
+	INVALID_SDEV_STATE,	/* Not a valid SCSI device state but a
+				 * symbolic name that can be used wherever
+				 * a value is needed that is different of
+				 * any valid SCSI device state. */
+	SDEV_CREATED,		/* device created but not added to sysfs
 				 * Only internal commands allowed (for inq) */
 	SDEV_RUNNING,		/* device properly configured
 				 * All commands allowed */