[PATCH] drivers/scsi/st.c: decrement in_use under the lock in st_open

[PATCH] drivers/scsi/st.c: decrement in_use under the lock in st_open

[Nate Dailey]

Hi, this patch changes the err_out case in st_open to decrement STp->in_use under the st_dev_arr_lock.

I'm just basing this on looking at the code (I didn't run into an actual problem here), but it seems like the right thing to do; st_open and release hold the lock when adjusting in_use in other places.

This is against kernel 2.6.12-rc2.

Nate Dailey
Stratus Technologies


Signed-off-by: Nate Dailey <nate.dailey@stratus.com>


--- linux-2.6.12-rc2/drivers/scsi/st.c.orig	2005-04-20 11:28:39.000000000 -0400
+++ linux-2.6.12-rc2/drivers/scsi/st.c	2005-04-20 11:30:08.000000000 -0400
@@ -1115,7 +1115,9 @@ static int st_open(struct inode *inode, 
 
  err_out:
 	normalize_buffer(STp->buffer);
+	write_lock(&st_dev_arr_lock);
 	STp->in_use = 0;
+	write_unlock(&st_dev_arr_lock);
 	scsi_device_put(STp->device);
 	return retval;
 

Re: [PATCH] drivers/scsi/st.c: decrement in_use under the lock in st_open

[Kai Makisara]

On Thu, 21 Apr 2005, Nate Dailey wrote:

> Hi, this patch changes the err_out case in st_open to decrement STp->in_use under the st_dev_arr_lock.
> 
> I'm just basing this on looking at the code (I didn't run into an actual 
> problem here), but it seems like the right thing to do; st_open and 
> release hold the lock when adjusting in_use in other places.
> 
I don't think it is necessary hold the lock when setting STp->in_use to 
zero. The problem is that the usage is not consistent in st. Either this  
patch should be included or the locking should be removed from st_release. 
I don't have any strong opinions about the best solution.

Thanks for pointing out this inconsistency.

-- 
Kai