Messages in this thread Patch in this message | | | Date | Wed, 14 May 2003 13:38:43 +0530 | From | Bharata B Rao <> | Subject | Re: 2.5.69-mjb1: undefined reference to `blk_queue_empty' |
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On Tue, May 13, 2003 at 08:11:55PM +0200, Jens Axboe wrote: > > > > > > /* For now we assume we have the device to ourselves */ > > > /* Just a quick sanity check */ > > > - if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) { > > > + if (elv_next_request(bdev_get_queue(dump_bdev->bdev))) { > > > /* i/o in flight - safer to quit */ > > > return -EBUSY; > > > } > > this looks horribly racy (of the io scheduler internals corrupting > kind), I don't see you holding the queue lock here. some io schedulers > do non-significant amount of work inside they next_request functions, > moving from back-end lists to dispatch queue. >
Jens,
All we want to do here is to check if there are requests in the queue. Hence thinking of using elv_queue_empty(). Do you think we still need to acquire queue lock for this ? This code will be run when we have stopped everything else in other cpus by putting them into spin.
--- 2569+mjb1/drivers/dump/dump_blockdev.c.orig Wed May 14 13:23:36 2003 +++ 2569+mjb1/drivers/dump/dump_blockdev.c Wed May 14 13:24:58 2003 @@ -258,10 +258,11 @@ dump_block_silence(struct dump_dev *dev) { struct dump_blockdev *dump_bdev = DUMP_BDEV(dev); + struct request_queue *q = bdev_get_queue(dump_bdev->bdev); /* For now we assume we have the device to ourselves */ /* Just a quick sanity check */ - if (!blk_queue_empty(bdev_get_queue(dump_bdev->bdev))) { + if (!elv_queue_empty(q)) { /* i/o in flight - safer to quit */ return -EBUSY; } Regards, Bharata. - 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/
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