block: fix infinite loop in __getblk_slow

commit 91f68c89d8f35fe98ea04159b9a3b42d0149478f upstream.

Commit 080399aaaf35 ("block: don't mark buffers beyond end of disk as
mapped") exposed a bug in __getblk_slow that causes mount to hang as it
loops infinitely waiting for a buffer that lies beyond the end of the
disk to become uptodate.

The problem was initially reported by Torsten Hilbrich here:

    https://lkml.org/lkml/2012/6/18/54

and also reported independently here:

    http://www.sysresccd.org/forums/viewtopic.php?f=13&t=4511

and then Richard W.M.  Jones and Marcos Mello noted a few separate
bugzillas also associated with the same issue.  This patch has been
confirmed to fix:

    https://bugzilla.redhat.com/show_bug.cgi?id=835019

The main problem is here, in __getblk_slow:

        for (;;) {
                struct buffer_head * bh;
                int ret;

                bh = __find_get_block(bdev, block, size);
                if (bh)
                        return bh;

                ret = grow_buffers(bdev, block, size);
                if (ret < 0)
                        return NULL;
                if (ret == 0)
                        free_more_memory();
        }

__find_get_block does not find the block, since it will not be marked as
mapped, and so grow_buffers is called to fill in the buffers for the
associated page.  I believe the for (;;) loop is there primarily to
retry in the case of memory pressure keeping grow_buffers from
succeeding.  However, we also continue to loop for other cases, like the
block lying beond the end of the disk.  So, the fix I came up with is to
only loop when grow_buffers fails due to memory allocation issues
(return value of 0).

The attached patch was tested by myself, Torsten, and Rich, and was
found to resolve the problem in call cases.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reported-and-Tested-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Josh Boyer <jwboyer@redhat.com>
[ Jens is on vacation, taking this directly  - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: bgn9000 <bgn9000@ubuntu.ubuntu-domain>
media: dvb-core: Release semaphore on error path dvb_register_device()

commit 82163edcdfa4eb3d74516cc8e9f38dd3d039b67d upstream.

There is a missing "up_write()" here. Semaphore should be released
before returning error value.

Signed-off-by: Santosh Nayak <santoshprasadnayak@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: bgn9000 <bgn9000@ubuntu.ubuntu-domain>
mtd: nandsim: don't open code a do_div helper

commit 596fd46268634082314b3af1ded4612e1b7f3f03 upstream.

We don't need to open code the divide function, just use div_u64 that
already exists and do the same job. While this is a straightforward
clean up, there is more to that, the real motivation for this.

While building on a cross compiling environment in armel, using gcc
4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5), I was getting the following build
error:

ERROR: "__aeabi_uldivmod" [drivers/mtd/nand/nandsim.ko] undefined!

After investigating with objdump and hand built assembly version
generated with the compiler, I narrowed __aeabi_uldivmod as being
generated from the divide function. When nandsim.c is built with
-fno-inline-functions-called-once, that happens when
CONFIG_DEBUG_SECTION_MISMATCH is enabled, the do_div optimization in
arch/arm/include/asm/div64.h doesn't work as expected with the open
coded divide function: even if the do_div we are using doesn't have a
constant divisor, the compiler still includes the else parts of the
optimized do_div macro, and translates the divisions there to use
__aeabi_uldivmod, instead of only calling __do_div_asm -> __do_div64 and
optimizing/removing everything else out.

So to reproduce, gcc 4.6 plus CONFIG_DEBUG_SECTION_MISMATCH=y and
CONFIG_MTD_NAND_NANDSIM=m should do it, building on armel.

After this change, the compiler does the intended thing even with
-fno-inline-functions-called-once, and optimizes out as expected the
constant handling in the optimized do_div on arm. As this also avoids a
build issue, I'm marking for Stable, as I think is applicable for this
case.

Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: bgn9000 <bgn9000@ubuntu.ubuntu-domain>
ARM: SAMSUNG: fix race in s3c_adc_start for ADC

commit 8265981bb439f3ecc5356fb877a6c2a6636ac88a upstream.

Checking for adc->ts_pend already claimed should be done with the
lock held.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: bgn9000 <bgn9000@ubuntu.ubuntu-domain>