Re: [PATCH]: complete cleanup of check_region

From: Jesper Juhl
Date: Mon Jun 11 2007 - 07:18:33 EST

On 08/06/07, Surya <surya.prabhakar@xxxxxxxxx> wrote:
> > 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.


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)
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};


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)
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]);
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;
@@ -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;
@@ -5801,6 +5811,7 @@ int __init sbpcd_init(void)
sbpcd_queue = blk_init_queue(do_sbpcd_request, &sbpcd_lock);
if (!sbpcd_queue) {
+ 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(addr[1],4);
return -EIO;
@@ -5850,6 +5862,7 @@ int __init sbpcd_init(void)
if (sbpcd_infop == NULL)
+ release_region(addr[1],4);
return -ENOMEM;
@@ -5894,6 +5907,7 @@ static void sbpcd_exit(void)
+ release_region(addr[1],4);
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.


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Jesper Juhl <jesper.juhl@xxxxxxxxx>
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