Hi Andries, Hi List!
Andries, thank you for your quick response,
>Well, among the irrelevant details you left out is the fact that
>it is not
> blk_size[dev->major] = NULL;
>but
> if(!dev->sizes)
> blk_size[dev->major] = NULL;
Well, this is absoloutely right, the behaviour to clear blk_size when
dev->sizes
is NULL looks sensible to me. But seven lines below it says
-unconditionaly-:
blk_size[dev->major] = NULL;
>So, the idea is that either this major has an array with sizes,
>and then one can find it in blk_size[dev->major], or it hasn't.
>You seem to have a situation where dev->sizes is NULL but
>blk_size[dev->major] is not? What device is this?
Our dev->sizes holds a pointer which (normally, when grok_partitions is
not running currently). We are running the dasd-device driver for channel
attached disks on mainframe architectures (drivers/s390/block/dasd*).
mit freundlichem Gruß / with kind regards
Carsten Otte
IBM Deutschland Entwicklung GmbH
Linux for 390/zSeries Development - Device Driver Team
Phone: +49/07031/16-4076
IBM internal phone: *120-4076
-- We are Linux. Resistance indicates that you're missing the point!Andries.Brouwer@cwi.nl on 06/07/2001 11:10:52 PM
Please respond to Andries.Brouwer@cwi.nl
To: Carsten Otte/Germany/IBM@IBMDE, linux-kernel@vger.kernel.org cc: Subject: Re: BUG: race-cond with partition-check and ll_rw_blk (all platforms, 2.4.*!)
From: COTTE@de.ibm.com
We just had a problem when running some formatting-utils on a large amount of disks synchronously: We got a NULL-pointer violation when accessig blk_size[major] for our major number. Further research showed, that grok_partitions was running at that time, which has been called by register_disk, which our device driver issues after a disk has been formatted. Grok_partitions first initializes blk_size[major] with a NULL pointer, detects the partitions and then assigns the original value to blk_size[major] again. Here's the interresting code from these functions, I cut some irrelevant things out: From grok_paritions: blk_size[dev->major] = NULL; check_partition(dev, MKDEV(dev->major, first_minor), 1 + first_minor); if (dev->sizes != NULL) { blk_size[dev->major] = dev->sizes; }; From generic_make_request: if (blk_size[major]) { if (blk_size[major][MINOR(bh->b_rdev)]) {
Can anyone explain to me, why grok_partitions has to clear this pointer?
... if (dev->sizes) blk_size[dev->major] = dev->sizes;
So, the idea is that either this major has an array with sizes, and then one can find it in blk_size[dev->major], or it hasn't. You seem to have a situation where dev->sizes is NULL but blk_size[dev->major] is not? What device is this?
Andries
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Fri Jun 15 2001 - 21:00:08 EST