Re: Usage question

Re: Usage question

[Dan Dennedy]

On Sat, 2005-04-02 at 15:55 +0200, Matthias Bläsing wrote:
> Am Sa, den 02.04.2005 schrieb Stefan Richter um 4:07:
> > ...CD/DVD-ROMs, because there are problems with device and host 
> > structures management if sr_mod of Linux 2.6 is involved. It is an old 
> > known bug whose cause has not yet been figured out.
> 
> There was a patch for the kernel on this list, which work quite good for
> me (sr.c and sr_ioctl.c have to be modified - Olaf Hering on
> 24.10.2004). I couldn't find any bad side effects of this.

Thanks, I located the message on the linux1394-devel list:
http://marc.theaimsgroup.com/?l=linux1394-devel&m=109862922621832&w=2

There is a very good report response to Olaf's little patch.
http://marc.theaimsgroup.com/?l=linux1394-devel&m=109925711513542&w=2

Please, others, try it as well. I'm going to....



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patch (was Usage question)

[Stefan Richter]

Dan Dennedy wrote on 2005-04-03:
> On Sat, 2005-04-02 at 15:55 +0200, Matthias Bläsing wrote:
[hotplugging of SBP-2 CD-ROMs]
>>There was a patch for the kernel on this list, which work quite good for
>>me (sr.c and sr_ioctl.c have to be modified - Olaf Hering on
>>24.10.2004). I couldn't find any bad side effects of this.
> 
> Thanks, I located the message on the linux1394-devel list:
> http://marc.theaimsgroup.com/?l=linux1394-devel&m=109862922621832&w=2
> 
> There is a very good report response to Olaf's little patch.
> http://marc.theaimsgroup.com/?l=linux1394-devel&m=109925711513542&w=2
> 
> Please, others, try it as well. I'm going to....

I tried it with up to two different CD-RWs and a HDD on the same FireWire
bus. Works for me. There have been other positive reports on linux1394-user
as well. Quote from Olaf's posting:

| The trouble starts in register_cdrom(), it sets the ->exit() function if
| the CD can do CDC_MRW_W.
| On unregister, it tries to send a packet to the device which is already
| gone.
|
| How about this patch?

diff -purN linux-2.6.9.orig/drivers/scsi/sr.c linux-2.6.9-olh/drivers/scsi/sr.c
--- linux-2.6.9.orig/drivers/scsi/sr.c	2004-10-22 19:02:43.545400072 +0200
+++ linux-2.6.9-olh/drivers/scsi/sr.c	2004-10-24 16:32:10.765682704 +0200
@@ -916,6 +918,7 @@ static void sr_kref_release(struct kref
  	struct gendisk *disk = cd->disk;

  	spin_lock(&sr_index_lock);
+	cd->use = 0;
  	clear_bit(disk->first_minor, sr_index_bits);
  	spin_unlock(&sr_index_lock);

diff -purN linux-2.6.9.orig/drivers/scsi/sr_ioctl.c linux-2.6.9-olh/drivers/scsi/sr_ioctl.c
--- linux-2.6.9.orig/drivers/scsi/sr_ioctl.c	2004-10-22 19:02:43.547399768 +0200
+++ linux-2.6.9-olh/drivers/scsi/sr_ioctl.c	2004-10-24 16:31:05.921540512 +0200
@@ -86,6 +86,11 @@ int sr_do_ioctl(Scsi_CD *cd, struct pack
          struct request *req;
  	int result, err = 0, retries = 0;

+	if(!cd->use) {
+		err = -ENODEV;
+		goto out;
+	}
+
  	SDev = cd->device;
  	SRpnt = scsi_allocate_request(SDev, GFP_KERNEL);
          if (!SRpnt) {


-- 
Stefan Richter
-=====-=-=-= -=-= --=--
http://arcgraph.de/sr/
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Re: Usage question

[Olaf Hering]

 On Sat, Apr 02, Dan Dennedy wrote:

> On Sat, 2005-04-02 at 15:55 +0200, Matthias Bläsing wrote:
> > Am Sa, den 02.04.2005 schrieb Stefan Richter um 4:07:
> > > ...CD/DVD-ROMs, because there are problems with device and host 
> > > structures management if sr_mod of Linux 2.6 is involved. It is an old 
> > > known bug whose cause has not yet been figured out.
> > 
> > There was a patch for the kernel on this list, which work quite good for
> > me (sr.c and sr_ioctl.c have to be modified - Olaf Hering on
> > 24.10.2004). I couldn't find any bad side effects of this.
> 
> Thanks, I located the message on the linux1394-devel list:
> http://marc.theaimsgroup.com/?l=linux1394-devel&m=109862922621832&w=2
> 
> There is a very good report response to Olaf's little patch.
> http://marc.theaimsgroup.com/?l=linux1394-devel&m=109925711513542&w=2
> 
> Please, others, try it as well. I'm going to....

This patch is just a workaround.
ide-scsi shows exactly the same oops. 
ide-scsi was fixed in 2.6.11 or 2.6.12, it should now have proper
refcounting. Someone has to implement the same for the sbp2 driver.
I cant help you with that challenge.
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