On Thu, Apr 05, 2001 at 11:03:44AM -0400, Phillip Ezolt wrote:
>
> The qlogic-isp driver causes a kernel crash on my Alpha/Linux machine.
>
> Unfortunately, it only happens under very heavy load, so it is not
> easily reproducible.
>
> The machine is running kernel 2.4.2 with TUX-W2 applied. (This is
> basically 2.4.2-ac24 with the tux server added.)
>
> The machine is a single-CPU DS10 with the following:
>
> SCSI subsystem driver Revision: 1.00
> qlogicisp: new isp1020 revision ID (5)
> scsi0: QLogic ISP1020 SCSI on PCI bus 00 device 78 irq 39 I/O base 0x8000
>
> 00:0f.0 SCSI storage controller: Q Logic ISP1020 (rev 05)
>
> I think that I have the line, and the reason for the crash.
>
> The line that causes it is qlogicisp.c (1054):
> ...
> void isp1020_intr_handler()
> ....
>
> if (sts->hdr.entry_type == ENTRY_STATUS)
> Cmnd->result = isp1020_return_status(sts);
> else
> Cmnd->result = DID_ERROR << 16;
> if (Cmnd->use_sg)
>
> >From the values in v0, and s0, I believe that Cmnd is NULL.
>
> The crash is the first place that Cmnd is accessed within the function.
>
> Is there a fix for this?
I've seen that before, but thought it had gone away... :-\
Essentially, IIRC, it gets the Cmnd value via a table entry, the entry
being determined by read of memory-mapped status info set by the
controller. If the status info is not valid for any reason, then odds
are that the Cmnd value will be also.
Suggestion:
Change the following code in the interrupt handler:
cmd_slot = sts->handle;
Cmnd = hostdata->cmd_slots[cmd_slot];
hostdata->cmd_slots[cmd_slot] = NULL;
to:
mb();
cmd_slot = sts->handle;
Cmnd = hostdata->cmd_slots[cmd_slot];
mb();
hostdata->cmd_slots[cmd_slot] = NULL;
and see if that makes a difference.
If it doesn't, we've more thinking to do... :-\
One could retry the sts->handle fetch a second time and compare values.
It would be interesting (but harder, I suspect) to know if we ever get
a bad value for cmd_slot but *not* end up with Cmnd== NULL...
--Jay++
-----------------------------------------------------------------------------
Jay A Estabrook Alpha Engineering - LINUX Project
Compaq Computer Corp. - MRO1-2/K20 (508) 467-2080
200 Forest Street, Marlboro MA 01752 [EMAIL PROTECTED]
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