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Date: Thu, 19 May 2011 11:05:34 -0700 From: Greg KH <gregkh@...e.de> To: linux-kernel@...r.kernel.org, stable@...nel.org Cc: stable-review@...nel.org, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, Tejun Heo <tj@...nel.org>, Jens Axboe <jaxboe@...ionio.com> Subject: [66/71] cdrom: always check_disk_change() on open 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Tejun Heo <tj@...nel.org> commit bf2253a6f00e8fea5b026e471e9f0d0a1b3621f2 upstream. cdrom_open() called check_disk_change() after the rest of open path succeeded which leads to the following bizarre behavior. * After media change, if the device opened without O_NONBLOCK, open_for_data() naturally fails with -ENOMEDIA and check_disk_change() is never called. The media is known to be gone and the open failure makes it obvious to the userland but device invalidation never happens. * But if the device is opened with O_NONBLOCK, all the checks are bypassed and cdrom_open() doesn't notice that the media is not there and check_disk_change() is called and invalidation happens. There's nothing to be gained by avoiding calling check_disk_change() on open failure. Common cases end up calling check_disk_change() anyway. All we get is inconsistent behavior. Fix it by moving check_disk_change() invocation to the top of cdrom_open() so that it always gets called regardless of how the rest of open proceeds. Stable: 2.6.38 Signed-off-by: Tejun Heo <tj@...nel.org> Reported-by: Amit Shah <amit.shah@...hat.com> Tested-by: Amit Shah <amit.shah@...hat.com> Signed-off-by: Jens Axboe <jaxboe@...ionio.com> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de> --- drivers/cdrom/cdrom.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/cdrom/cdrom.c +++ b/drivers/cdrom/cdrom.c @@ -986,6 +986,9 @@ int cdrom_open(struct cdrom_device_info cdinfo(CD_OPEN, "entering cdrom_open\n"); + /* open is event synchronization point, check events first */ + check_disk_change(bdev); + /* if this was a O_NONBLOCK open and we should honor the flags, * do a quick open without drive/disc integrity checks. */ cdi->use_count++; @@ -1012,9 +1015,6 @@ int cdrom_open(struct cdrom_device_info cdinfo(CD_OPEN, "Use count for \"/dev/%s\" now %d\n", cdi->name, cdi->use_count); - /* Do this on open. Don't wait for mount, because they might - not be mounting, but opening with O_NONBLOCK */ - check_disk_change(bdev); return 0; err_release: if (CDROM_CAN(CDC_LOCK) && cdi->options & CDO_LOCK) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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