Re: mcdx -- do_request(): non-read command to cd!!

["Pekka Enberg" <penberg@cs.helsinki.fi>]

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On 3/31/07, Rene Herman <rene.herman@gmail.com> wrote:
> There's quite a bit of noise in dmesg though. Repeated 5 times:
>
> ===BUG: scheduling while atomic: mount/0x00000001/1166
>   [<c1170bff>] __sched_text_start+0x57/0x574
>   [<c1171964>] schedule_timeout+0x70/0x8f
>   [<c10199b2>] process_timeout+0x0/0x5
>   [<c11716a2>] interruptible_sleep_on_timeout+0x5d/0xa5
>   [<c100e695>] default_wake_function+0x0/0xc
>   [<c482b8fb>] mcdx_xfer+0xae/0x2a5 [mcdx]

[snip]

>   [<c482b473>] do_mcdx_request+0x9b/0xd2 [mcdx]
>   [<c1096d06>] __generic_unplug_device+0x1d/0x1f
>   [<c1096d19>] generic_unplug_device+0x11/0x29

Looks like mcdx_xfer is sleeping while holding q->queue_lock. The
attached (untested) patch should fix it.

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diff --git a/drivers/cdrom/mcdx.c b/drivers/cdrom/mcdx.c
index f574962..e14dc03 100644
--- a/drivers/cdrom/mcdx.c
+++ b/drivers/cdrom/mcdx.c
@@ -577,11 +577,14 @@ static void do_mcdx_request(request_queue_t * q)
 	if (!req)
 		return;
 
+	spin_unlock_irq(q->queue_lock);
+
 	stuffp = req->rq_disk->private_data;
 
 	if (!stuffp->present) {
 		xwarn("do_request(): bad device: %s\n",req->rq_disk->disk_name);
 		xtrace(REQUEST, "end_request(0): bad device\n");
+		spin_lock_irq(q->queue_lock);
 		end_request(req, 0);
 		return;
 	}
@@ -589,6 +592,7 @@ static void do_mcdx_request(request_queue_t * q)
 	if (stuffp->audio) {
 		xwarn("do_request() attempt to read from audio cd\n");
 		xtrace(REQUEST, "end_request(0): read from audio\n");
+		spin_lock_irq(q->queue_lock);
 		end_request(req, 0);
 		return;
 	}
@@ -599,6 +603,7 @@ static void do_mcdx_request(request_queue_t * q)
 	if (req->cmd != READ) {
 		xwarn("do_request(): non-read command to cd!!\n");
 		xtrace(REQUEST, "end_request(0): write\n");
+		spin_lock_irq(q->queue_lock);
 		end_request(req, 0);
 		return;
 	}
@@ -613,6 +618,7 @@ static void do_mcdx_request(request_queue_t * q)
 					  req->nr_sectors);
 
 			if (i == -1) {
+				spin_lock_irq(q->queue_lock);
 				end_request(req, 0);
 				goto again;
 			}
@@ -620,10 +626,12 @@ static void do_mcdx_request(request_queue_t * q)
 			req->nr_sectors -= i;
 			req->buffer += (i * 512);
 		}
+		spin_lock_irq(q->queue_lock);
 		end_request(req, 1);
 		goto again;
 
 		xtrace(REQUEST, "end_request(1)\n");
+		spin_lock_irq(q->queue_lock);
 		end_request(req, 1);
 	}