Assumption in sym53c8xx.c failed

Assumption in sym53c8xx.c failed

[Christian Kurz]

Hi,

I'm currently running 2.4.2-ac28 and today I got a failing assumption in
sym53c8xx.c. I'm not sure about the exact steps that I did to produce
this error, but it must have been something like: cdparanoia -blank=all,
then sending Ctrl+C to this process and after it's been killed
cdparanoia -blank=fast. I then got assertion: k!=-1 failed. But I found
no hint about this in the messages or syslog file. So I looked through
sym53c8xx.c to find this code and it seems like line 10123 is
responsible for creating this error and kernel panic. Should this be the
normal behaviour or is this a bug in the code?

Christian
-- 
Truth is the most valuable thing we have -- so let us economize it.
                -- Mark Twain

Re: Assumption in sym53c8xx.c failed

[Gérard Roudier]

On Sat, 31 Mar 2001, Christian Kurz wrote:

> Hi,
> 
> I'm currently running 2.4.2-ac28 and today I got a failing assumption in
> sym53c8xx.c. I'm not sure about the exact steps that I did to produce
> this error, but it must have been something like: cdparanoia -blank=all,
> then sending Ctrl+C to this process and after it's been killed
> cdparanoia -blank=fast. I then got assertion: k!=-1 failed. But I found
> no hint about this in the messages or syslog file. So I looked through
> sym53c8xx.c to find this code and it seems like line 10123 is
> responsible for creating this error and kernel panic. Should this be the
> normal behaviour or is this a bug in the code?

This might well be both at the same time. I mean normal behaviour given a
bug in the code. :-)

Could you try this tiny patch and let me know:

--- sym53c8xx.c.0402	Mon Apr  2 15:58:32 2001
+++ sym53c8xx.c	Mon Apr  2 16:02:43 2001
@@ -10167,14 +10167,13 @@
 				if (i >= MAX_START*2)
 					i = 0;
 			}
-			assert(k != -1);
 			if (k != 1) {
 				np->squeue[k] = np->squeue[i]; /* Idle task */
 				np->squeueput = k; /* Start queue pointer */
-				cp->host_status = HS_ABORTED;
-				cp->scsi_status = S_ILLEGAL;
-				ncr_complete(np, cp);
 			}
+			cp->host_status = HS_ABORTED;
+			cp->scsi_status = S_ILLEGAL;
+			ncr_complete(np, cp);
 		}
 		break;
 	/*

What happens is that this part of the driver code assumed that the CCB for
an IO to abort is queued to the SCSI SCRIPTS. This is not always true
since the driver may temporarily not queue all IOs to SCRIPTS. This may
happens on QUEUE FULL condition or for devices that donnot accept tagged
commands, for example.

Regards,
  Gérard.

Re: Assumption in sym53c8xx.c failed

[Gérard Roudier]

Hello,

The patch I sent you yesterday has a typo that can lead to serious
breakage. This has been pointed out by Michal Jaegermann. Thanks, Michal.
(k must be compared against -1 and not against 1)

You want to apply this new tiny patch instead and let me know if it fixes:

--- sym53c8xx.c.0402	Mon Apr  2 15:58:32 2001
+++ sym53c8xx.c	Tue Apr  3 07:15:00 2001
@@ -10167,14 +10167,13 @@
 				if (i >= MAX_START*2)
 					i = 0;
 			}
-			assert(k != -1);
-			if (k != 1) {
+			if (k != -1) {
 				np->squeue[k] = np->squeue[i]; /* Idle task */
 				np->squeueput = k; /* Start queue pointer */
-				cp->host_status = HS_ABORTED;
-				cp->scsi_status = S_ILLEGAL;
-				ncr_complete(np, cp);
 			}
+			cp->host_status = HS_ABORTED;
+			cp->scsi_status = S_ILLEGAL;
+			ncr_complete(np, cp);
 		}
 		break;
 	/*
--------------------- Cut Here -----------------

  Gérard.

On Mon, 2 Apr 2001, Gérard Roudier wrote:

> 
> 
> On Sat, 31 Mar 2001, Christian Kurz wrote:
> 
> > Hi,
> > 
> > I'm currently running 2.4.2-ac28 and today I got a failing assumption in
> > sym53c8xx.c. I'm not sure about the exact steps that I did to produce
> > this error, but it must have been something like: cdparanoia -blank=all,
> > then sending Ctrl+C to this process and after it's been killed
> > cdparanoia -blank=fast. I then got assertion: k!=-1 failed. But I found
> > no hint about this in the messages or syslog file. So I looked through
> > sym53c8xx.c to find this code and it seems like line 10123 is
> > responsible for creating this error and kernel panic. Should this be the
> > normal behaviour or is this a bug in the code?
> 
> This might well be both at the same time. I mean normal behaviour given a
> bug in the code. :-)
> 
> Could you try this tiny patch and let me know:
> 
> --- sym53c8xx.c.0402	Mon Apr  2 15:58:32 2001
> +++ sym53c8xx.c	Mon Apr  2 16:02:43 2001
> @@ -10167,14 +10167,13 @@
>  				if (i >= MAX_START*2)
>  					i = 0;
>  			}
> -			assert(k != -1);
>  			if (k != 1) {
>  				np->squeue[k] = np->squeue[i]; /* Idle task */
>  				np->squeueput = k; /* Start queue pointer */
> -				cp->host_status = HS_ABORTED;
> -				cp->scsi_status = S_ILLEGAL;
> -				ncr_complete(np, cp);
>  			}
> +			cp->host_status = HS_ABORTED;
> +			cp->scsi_status = S_ILLEGAL;
> +			ncr_complete(np, cp);
>  		}
>  		break;
>  	/*
> 
> What happens is that this part of the driver code assumed that the CCB for
> an IO to abort is queued to the SCSI SCRIPTS. This is not always true
> since the driver may temporarily not queue all IOs to SCRIPTS. This may
> happens on QUEUE FULL condition or for devices that donnot accept tagged
> commands, for example.
> 
> Regards,
>   Gérard.
> 
>