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To: Ron Lawrence <rlawrence@netraverse.com>
Cc: <linux-kernel@vger.kernel.org>, Jens Axboe <axboe@suse.de>
Subject: Re: CDROM ioctl bug (fwd)
In-Reply-To: <Pine.LNX.4.33.0111281009140.1724-100000@monster.jayfay.com>
From: Peter Osterlund <petero2@telia.com>
Date: 29 Nov 2001 00:51:46 +0100
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Ron Lawrence <rlawrence@netraverse.com> writes:

> busy. Here are the symptoms of my problem : doing reads from a CDROM
> device intermingled with CDROM_MEDIA_CHANGED ioctls causes long pauses
> during the ioctl. This behavior started in 2.4.10. The ioctl can take a
> very long time to return, especially if reading large chunks.

This patch fixes the problem for my USB CDROM device. Maybe a similar
patch is needed for the IDE case, I haven't looked yet.

In general, who is responsible for unplugging the request queue after
queuing an ioctl command?

--- linux/drivers/scsi/scsi.c.old	Thu Nov 29 00:42:16 2001
+++ linux/drivers/scsi/scsi.c	Thu Nov 29 00:32:28 2001
@@ -767,14 +767,17 @@
 void scsi_wait_req (Scsi_Request * SRpnt, const void *cmnd ,
  		  void *buffer, unsigned bufflen, 
  		  int timeout, int retries)
 {
+	request_queue_t *q;
 	DECLARE_COMPLETION(wait);
 	
 	SRpnt->sr_request.waiting = &wait;
 	SRpnt->sr_request.rq_status = RQ_SCSI_BUSY;
 	scsi_do_req (SRpnt, (void *) cmnd,
 		buffer, bufflen, scsi_wait_done, timeout, retries);
+	q = &SRpnt->sr_device->request_queue;
+	generic_unplug_device(q);
 	wait_for_completion(&wait);
 	SRpnt->sr_request.waiting = NULL;
 	if( SRpnt->sr_command != NULL )
 	{

-- 
Peter ?sterlund             petero2@telia.com
Sk?ndalsv?gen 35            http://w1.894.telia.com/~u89404340
S-128 66 Sk?ndal            +46 8 942647
Sweden
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