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SubjectRe: [PATCH] iio: ensure ret is initialized to zero before entering do loop
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On 06/09/16 18:10, Brian Norris wrote:
> Hi,
>
> On Mon, Sep 05, 2016 at 09:03:26PM +0100, Jonathan Cameron wrote:
>> On 05/09/16 15:39, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> A recent fix to iio_buffer_read_first_n_outer removed ret from being set by
>>> a return from wait_event_interruptible and also added a continue in a loop
>>> which causes the variable ret to not be set when it reaches the end of the
>>> loop. Fix this by initializing ret to zero.
>>>
>>> Also remove extraneous white space at the end of the loop.
>>>
>>> Fixes: fcf68f3c0bb2a5 ("fix sched WARNING "do not call blocking ops when !TASK_RUNNING")
>
> Not that it really matters, but if the commit is still going to be
> amended at all, the subject was "iio: fix ...", not just "fix ...".
> Definitely not important though.
>
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> Good find. Strange that got through 0-day without a warning...
>>
>> Cc'd Brian as author of the fix this is fixing.
>> Brian can you sanity check this patch as well.
>
> Indeed, looks fine, and works fine:
>
> Tested-by: Brian Norris <briannorris@chromium.org>
> Reviewed-by: Brian Norris <briannorris@chromium.org>
Hi Brian,

Thanks for checking this out. Unfortunately I've already
applied it to fixes-togreg branch of iio.git which is strictly
non rebasing so we'll have to rely on the email trace rather
than git history to pick up on your tested by /reviewed by!

Made me more comfortable sending the pull request to Greg
though so thanks!

Jonathan
>
> Thanks for the fix Colin, and sorry for not noticing that error :(
>
>> Applied to the fixes-togreg branch of iio.git and marked for stable.
>> Ah well, another one for the statistics on stable patches that introduce bugs while
>> fixing other bugs.
>>
>> Pretty unlikely this will be hit I think, but in theory you never know.
>>
>> Jonathan
>>> ---
>>> drivers/iio/industrialio-buffer.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
>>> index 49bf9c5..158aaf4 100644
>>> --- a/drivers/iio/industrialio-buffer.c
>>> +++ b/drivers/iio/industrialio-buffer.c
>>> @@ -110,7 +110,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
>>> DEFINE_WAIT_FUNC(wait, woken_wake_function);
>>> size_t datum_size;
>>> size_t to_wait;
>>> - int ret;
>>> + int ret = 0;
>>>
>>> if (!indio_dev->info)
>>> return -ENODEV;
>>> @@ -153,7 +153,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
>>> ret = rb->access->read_first_n(rb, n, buf);
>>> if (ret == 0 && (filp->f_flags & O_NONBLOCK))
>>> ret = -EAGAIN;
>>> - } while (ret == 0);
>>> + } while (ret == 0);
>
> Personally, I avoided the temptation to fix the whitespace error in a
> bugfix patch. But this does scratch my itch :)
>
> Brian
>
>>> remove_wait_queue(&rb->pollq, &wait);
>>>
>>> return ret;
>>>
>>
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