[8006] in linux-scsi channel archive
problems with cd changer
daemon@ATHENA.MIT.EDU (Philip Blundell)
Sun Feb 6 07:37:16 2000
To: linux-scsi@vger.rutgers.edu
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Date: Sun, 06 Feb 2000 12:34:39 +0000
From: Philip Blundell <Philip.Blundell@pobox.com>
Message-Id: <E12HQtj-0000f2-00@kings-cross.london.uk.eu.org>
Using 2.3.42 I had a couple of problems with a multi-LUN CD-ROM changer.
First, I was getting a NULL dereference inside scsi_allocate_device. This
patch seems to fix it:
--- clean/linux/drivers/scsi/scsi.c Sun Feb 6 12:28:31 2000
+++ linux/drivers/scsi/scsi.c Sun Feb 6 12:31:01 2000
@@ -330,8 +330,7 @@
* If asked to wait, we need to wait, otherwise
* return NULL.
*/
- SCpnt = NULL;
- break;
+ goto wait;
}
}
/*
@@ -342,6 +341,7 @@
break;
}
}
+ wait:
/*
* If we couldn't find a free command block, and we have been
* asked to wait, then do so.
But, with that patch applied, "insmod sr_mod" was hanging forever in this
function. It turns out that the SCSI bus scan was leaving `device_active' set
to one. This patch seems to avoid the problem:
--- clean/linux/drivers/scsi/scsi_scan.c Sun Feb 6 12:28:31 2000
+++ linux/drivers/scsi/scsi_scan.c Sun Feb 6 11:55:48 2000
@@ -262,7 +262,7 @@
Scsi_Cmnd *SCpnt;
unsigned char *scsi_result;
unsigned char scsi_result0[256];
- Scsi_Device *SDpnt;
+ Scsi_Device *SDpnt, *oldSDpnt;
Scsi_Device *SDtail;
int sparse_lun;
@@ -331,6 +331,7 @@
*/
atomic_inc(&shpnt->host_active);
atomic_inc(&SDpnt->device_active);
+ oldSDpnt = SDpnt;
if (hardcoded == 1) {
Scsi_Device *oldSDpnt = SDpnt;
@@ -412,7 +413,7 @@
* so we know when everything is quiet.
*/
atomic_dec(&shpnt->host_active);
- atomic_dec(&SDpnt->device_active);
+ atomic_dec(&oldSDpnt->device_active);
leave:
Could one of the experts please take a look?
Thanks
p.
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