Re: PROBLEM: Oops in 2.6.3 with lots of SG_IO activity - [PATCH]

[Brian King <brking@us.ibm.com>]

Testcase ran overnight without any problems.

-Brian


Brian King wrote:
> Attached is a patch which seems to fix the oops for me. Without the patch
> I can consistently reproduce the oops in just a couple minutes. With the
> patch I have been running for close to an hour without problems so far.
> Doug, does this look ok? I'm going to let my testcase run overnight as well
> and will post the results tomorrow.
> 
> 
>> I have been experiencing occasional oopses in some testing I have been
>> doing and have recently been able to aggravate the problem to recreate
>> the oops quite quickly. If I do lots of overlapped SG_IO ioctls while
>> also doing heavy disk I/O, I can recreate the oops within a few minutes,
>> although I have also seen the problem under very little load. I have
>> seen the problem using both the ipr and sym2 drivers.
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
> 
> The patch fixes a race condition in sg_cmd_done that results in an oops.
> 
> 
> ---
> 
> 
> diff -puN drivers/scsi/sg.c~sg_cmd_done_oops drivers/scsi/sg.c
> --- linux-2.6.4-rc2/drivers/scsi/sg.c~sg_cmd_done_oops	2004-03-06 22:08:45.000000000 -0600
> +++ linux-2.6.4-rc2-brking/drivers/scsi/sg.c	2004-03-06 22:55:12.000000000 -0600
> @@ -1256,7 +1256,6 @@ sg_cmd_done(Scsi_Cmnd * SCpnt)
>  	SRpnt->sr_request->rq_disk = NULL; /* "sg" _disowns_ request blk */
>  
>  	srp->my_cmdp = NULL;
> -	srp->done = 1;
>  
>  	SCSI_LOG_TIMEOUT(4, printk("sg_cmd_done: %s, pack_id=%d, res=0x%x\n",
>  		sdp->disk->disk_name, srp->header.pack_id, (int) SRpnt->sr_result));
> @@ -1312,8 +1311,9 @@ sg_cmd_done(Scsi_Cmnd * SCpnt)
>  	}
>  	if (sfp && srp) {
>  		/* Now wake up any sg_read() that is waiting for this packet. */
> -		wake_up_interruptible(&sfp->read_wait);
>  		kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
> +		srp->done = 1;
> +		wake_up_interruptible(&sfp->read_wait);
>  	}
>  }
>  
> 
> _


-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center