Re: [PATCH]: complete cleanup of check_region

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On 08/06/07, Surya <[email protected]> wrote:
<snip>
> >                 msg(DBG_INI,"check_drives done.\n");
> > +               if(request_region_flag==0)
> > +                       release_region(addr[1],4);
>
> I know the driver in its current version just tests if the region is
> available and doesn't hang on to it, but I'm wondering if that's not a
> bug.  Shouldn't we actually hold on to this region as long as the
> driver is loaded and only release the region in the sbpcd_exit()
> function, just loke we do with the "CDo_command" region?
But if any of the conditions fail after the request_region code, it is
returning an error and exiting out of init. Dont we need to cleanup
request_region's allocation before we exit.

Probably.

Infact I had a feeling that
CDo_command region cleanup was not perfect. Did a cleanup of both the
regions wherever we have a return out of the function.

That makes sense to me.

Please have a look at the below patch.


diff --git a/drivers/cdrom/sbpcd.c b/drivers/cdrom/sbpcd.c
index a1283b1..0a85b1b 100644
--- a/drivers/cdrom/sbpcd.c
+++ b/drivers/cdrom/sbpcd.c
@@ -358,6 +358,10 @@
  * Add bio/kdev_t changes for 2.5.x required to make it work again.
  * Still room for improvement in the request handling here if anyone
  * actually cares.  Bring your own chainsaw.    Paul G.  02/2002
+ *
+ *

Why two blank comment lines?  Isn't one enough?

+ * Cleaned up the reference for deprecated check_region to
+ * request_region.            - Surya Prabhakar N      08/07/2007
  */


@@ -555,6 +559,8 @@ static struct cdrom_read_audio read_audio;
 static unsigned char msgnum;
 static char msgbuf[80];

+static int addr[2];
+
 static int max_drives = MAX_DRIVES;
 module_param(max_drives, int, 0);
 #ifndef MODULE
@@ -5638,7 +5644,7 @@ int __init sbpcd_init(void)
 #endif
 {
        int i=0, j=0;

Blank line between variable declarations and code please.

-       int addr[2]={1, CDROM_PORT};
+       addr[2]={1, CDROM_PORT};
        int port_index;

Keep the variables together and seperate from the code. Like this :

{
      int i=0, j=0;
      int port_index;

      addr[2]={1, CDROM_PORT};
...



        sti();

Just in case you are bored, at some point those cli()/sti() need to go
away as well and be replaced with proper locking. But that's a
different patch :-)

@@ -5670,9 +5676,9 @@ int __init sbpcd_init(void)
        {
                addr[1]=sbpcd[port_index];
                if (addr[1]==0) break;
-               if (check_region(addr[1],4))
+               if (!request_region(addr[1],4, "sbpcd driver"))
                {
-                       msg(DBG_INF,"check_region: %03X is not free.\n",addr[1]);
+                       msg(DBG_INF,"request_region: %03X is not free.\n",addr[1]);
                        continue;
                }
                if (sbpcd[port_index+1]==2) type=str_sp;
@@ -5699,6 +5705,7 @@ int __init sbpcd_init(void)
        if (ndrives==0)
        {
                msg(DBG_INF, "No drive found.\n");
+               release_region(addr[1],4);

If we get here after actually having obtained a region an ndrives is
then 0, then we should ofcourse release the region before we bail out.
makes sense.

 #ifdef MODULE
                return -EIO;
 #else
@@ -5775,6 +5782,7 @@ int __init sbpcd_init(void)
        if (!request_region(CDo_command,4,major_name))
        {
                printk(KERN_WARNING "sbpcd: Unable to request region 0x%x\n", CDo_command);
+               release_region(addr[1],4);
                return -EIO;
        }


This makes sense. If we bail out due to not being able to obtain the
CDo_command region, then we should release the other region.

@@ -5788,6 +5796,8 @@ int __init sbpcd_init(void)
 #endif /* SOUND_BASE */

        if (register_blkdev(MAJOR_NR, major_name)) {
+               release_region(CDo_command,4);
+               release_region(addr[1],4);
 #ifdef MODULE
                return -EIO;
 #else
@@ -5801,6 +5811,7 @@ int __init sbpcd_init(void)
        sbpcd_queue = blk_init_queue(do_sbpcd_request, &sbpcd_lock);
        if (!sbpcd_queue) {
                release_region(CDo_command,4);
+               release_region(addr[1],4);
                unregister_blkdev(MAJOR_NR, major_name);
                return -ENOMEM;
        }
@@ -5834,6 +5845,7 @@ int __init sbpcd_init(void)
                                printk("Can't unregister %s\n", major_name);
                        }
                        release_region(CDo_command,4);
+                       release_region(addr[1],4);
                        blk_cleanup_queue(sbpcd_queue);
                        return -EIO;
                }
@@ -5850,6 +5862,7 @@ int __init sbpcd_init(void)
                if (sbpcd_infop == NULL)
                {
                         release_region(CDo_command,4);
+                       release_region(addr[1],4);
                        blk_cleanup_queue(sbpcd_queue);
                         return -ENOMEM;
                }
@@ -5894,6 +5907,7 @@ static void sbpcd_exit(void)
                return;
        }
        release_region(CDo_command,4);
+       release_region(addr[1],4);
        blk_cleanup_queue(sbpcd_queue);
        for (j=0;j<NR_SBPCD;j++)
        {

Kindly update if this is Ok. I will proceed with the original patch.


This looks a lot better to me. I have only given it a quick look, but
I don't see any major problems.

-surya.

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