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    SubjectRe: [TOME] Re: [PATCH 1/1] Add check for dirty_writeback_interval in bdi_wakeup_thread_delayed
    * On Mon, Apr 18, 2011 at 10:02:04AM +1000, Dave Chinner <david@fromorbit.com> wrote:
    >On Sun, Apr 17, 2011 at 09:53:08PM +0530, Raghavendra D Prabhu wrote:
    >> In the function bdi_wakeup_thread_delayed, no checks are performed on
    >> dirty_writeback_interval unlike other places and timeout is being set to
    >> zero as result, thus defeating the purpose. So, I have changed it to be
    >> passed default value of interval which is 500 centiseconds, when it is
    >> set to zero.
    >> I have also verified this and tested it.

    >> Signed-off-by: Raghavendra D Prabhu <rprabhu@wnohang.net>
    >> ---
    >> mm/backing-dev.c | 5 ++++-
    >> 1 files changed, 4 insertions(+), 1 deletions(-)

    >> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
    >> index befc875..d06533c 100644
    >> --- a/mm/backing-dev.c
    >> +++ b/mm/backing-dev.c
    >> @@ -336,7 +336,10 @@ void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
    >> {
    >> unsigned long timeout;
    >> - timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
    >> + if (dirty_writeback_interval)
    >> + timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
    >> + else
    >> + timeout = msecs_to_jiffies(5000);
    >> mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout);
    >> }
    >
    >Isn't the problem that the sysctl handler does not have a min/max
    >valid value set? I.e. to prevent invalid values from being set in
    >the first place?
    >
    >Cheers,
    >
    >Dave.
    0 is a valid value for dirty_writeback_interval which according to the
    definition/documentation is disabled when set to 0. In other places, a constraint
    check is done on that value except here.
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