Re: bio refcount problem

From: Philip R Auld
Date: Fri Feb 18 2005 - 09:28:18 EST


Hi,

Rumor has it that on Fri, Feb 18, 2005 at 02:59:32PM +0100 Jens Axboe said:
> On Fri, Feb 18 2005, Philip R Auld wrote:

...
> > Or make all users of submit_bio take and release and extra reference
> > like submit_bh.
>
> The queue lock is still held at that point, so the driver hasn't had a
> chance to process the request yet.

Interesting. This is not a theoretical problem though. I've got traces of
the oops showing the bio getting freed before the bio_sync(bio) test.
When you say driver here what level do you mean? scsi_request_fn at
least drops the queue lock.

What if it's merged instead of added directly? That could also get to
the same place.

The end_io callback _is_ getting called before __make_request
does its "if(bio_sync(bio))" test.


Cheers,

Phil


>
> --
> Jens Axboe

--
Philip R. Auld, Ph.D. Egenera, Inc.
Software Architect 165 Forest St.
(508) 858-2628 Marlboro, MA 01752
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/