2007-08-04 21:49:05

by Rafał Bilski

[permalink] [raw]
Subject: [PATCH] Remove bdput from do_open() in fs/block_dev.c

I mistyped
# echo /dev/hdc1 >/sys/module/block2mtd/parameters/block2mt
instead of sdc1. There is no /dev/hdc1. I have DVD-ROM as /dev/hdc.
# dmesg
block2mtd: version $Revision: 1.30 $
block2mtd: error: cannot open device /dev/hdc1
Looks right, but tray is locked. And it doesn't want to get out.
# eject
hdc: irq timeout: status=0xd0 { Busy }
ide: failed opcode was: unknown
WARNING: at kernel/irq/resend.c:70 check_irq_resend()
[<c013444b>] check_irq_resend+0xab/0xc0
[<c0133e2a>] enable_irq+0x4a/0xa0
[<c02c26e7>] ide_error+0x47/0xa0
[<c02d1e60>] cdrom_newpc_intr+0x0/0x300
[<c02c2bc0>] ide_timer_expiry+0x1e0/0x2d0
[<c02c29e0>] ide_timer_expiry+0x0/0x2d0
[<c011b986>] run_timer_softirq+0x116/0x160
[<c0127e75>] hrtimer_interrupt+0x165/0x1a0
[<c0118772>] __do_softirq+0x42/0x90
[<c01187e6>] do_softirq+0x26/0x30
[<c0118aaa>] irq_exit+0x5a/0x60
[<c0104817>] do_IRQ+0x47/0x80
[<c0102c23>] common_interrupt+0x23/0x30
[<c0281a46>] acpi_processor_idle+0x162/0x380
[<c0100d0e>] cpu_idle+0x4e/0x70
[<c0524ac5>] start_kernel+0x1f5/0x240
[<c05243a0>] unknown_bootoption+0x0/0x1e0
=======================

Removing bdput from do_open() in fs/block_dev.c seems
to be a cure for irq timeout.

Signed-off-by: Rafa? Bilski <[email protected]>
---
diff --git a/fs/block_dev.c b/fs/block_dev.c
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1120,7 +1120,6 @@ static int do_open(struct block_device *
disk = get_gendisk(bdev->bd_dev, &part);
if (!disk) {
unlock_kernel();
- bdput(bdev);
return ret;
}
owner = disk->fops->owner;

----------------------------------------------------------------------
Wszystko czego potrzebujesz latem: kremy do opalania,
stroje kapielowe, maly romans

>>>http://link.interia.pl/f1b15


2007-08-07 22:24:00

by Andrew Morton

[permalink] [raw]
Subject: Re: [PATCH] Remove bdput from do_open() in fs/block_dev.c

On Sat, 04 Aug 2007 23:48:34 +0200
Rafa__ Bilski <[email protected]> wrote:

> I mistyped
> # echo /dev/hdc1 >/sys/module/block2mtd/parameters/block2mt
> instead of sdc1. There is no /dev/hdc1. I have DVD-ROM as /dev/hdc.
> # dmesg
> block2mtd: version $Revision: 1.30 $
> block2mtd: error: cannot open device /dev/hdc1
> Looks right, but tray is locked. And it doesn't want to get out.
> # eject
> hdc: irq timeout: status=0xd0 { Busy }
> ide: failed opcode was: unknown
> WARNING: at kernel/irq/resend.c:70 check_irq_resend()
> [<c013444b>] check_irq_resend+0xab/0xc0
> [<c0133e2a>] enable_irq+0x4a/0xa0
> [<c02c26e7>] ide_error+0x47/0xa0
> [<c02d1e60>] cdrom_newpc_intr+0x0/0x300
> [<c02c2bc0>] ide_timer_expiry+0x1e0/0x2d0
> [<c02c29e0>] ide_timer_expiry+0x0/0x2d0
> [<c011b986>] run_timer_softirq+0x116/0x160
> [<c0127e75>] hrtimer_interrupt+0x165/0x1a0
> [<c0118772>] __do_softirq+0x42/0x90
> [<c01187e6>] do_softirq+0x26/0x30
> [<c0118aaa>] irq_exit+0x5a/0x60
> [<c0104817>] do_IRQ+0x47/0x80
> [<c0102c23>] common_interrupt+0x23/0x30
> [<c0281a46>] acpi_processor_idle+0x162/0x380
> [<c0100d0e>] cpu_idle+0x4e/0x70
> [<c0524ac5>] start_kernel+0x1f5/0x240
> [<c05243a0>] unknown_bootoption+0x0/0x1e0
> =======================
>
> Removing bdput from do_open() in fs/block_dev.c seems
> to be a cure for irq timeout.
>
> Signed-off-by: Rafa__ Bilski <[email protected]>
> ---
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -1120,7 +1120,6 @@ static int do_open(struct block_device *
> disk = get_gendisk(bdev->bd_dev, &part);
> if (!disk) {
> unlock_kernel();
> - bdput(bdev);
> return ret;
> }
> owner = disk->fops->owner;
>

>From my reading, this patch will fix the blkdev_get() error path, but will
break the blkdev_open() path.

It could be that we also need to add a bdput() into blkdev_open() if
do_open() failed (to balance blkdev_open()'s bd_acquire()).

It's pretty damn ugly that do_open() attempts to fix up the caller's
refcounting.