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Remove bdput from do_open() in fs/block_dev.c

PATCH In review Rafał Bilski 2 participants 2 messages Aug 4, 2007 – Aug 7, 2007 VFS

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PATCH 1/1 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.

fs/block_dev.c renamed from fs/block_dev.c b/fs/block_dev.c --- a/fs/block_dev.c +0 -0
@@ -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

Quoted 1 line
Quoted 1 line
Quoted 1 line

http://link.interia.pl/f1b15

#1 lore raw
Quoted 48 lines · 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.

---

fs/block_dev.c +0 -1
@@ -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;
Quoted 1 line

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.