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    Subject[34-longterm 059/247] fix jiffy calculations in calibrate_delay_direct to handle overflow
    Date
    From: Tim Deegan <Tim.Deegan@citrix.com>

    -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
    -------------------

    commit 70a062286b9dfcbd24d2e11601aecfead5cf709a upstream.

    Fixes a hang when booting as dom0 under Xen, when jiffies can be
    quite large by the time the kernel init gets this far.

    Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
    [jbeulich@novell.com: !time_after() -> time_before_eq() as suggested by Jiri Slaby]
    Signed-off-by: Jan Beulich <jbeulich@novell.com>
    Cc: Jiri Slaby <jslaby@suse.cz>
    Cc: Jeremy Fitzhardinge <jeremy@goop.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    init/calibrate.c | 6 +++---
    1 files changed, 3 insertions(+), 3 deletions(-)

    diff --git a/init/calibrate.c b/init/calibrate.c
    index 6eb48e5..24fe022 100644
    --- a/init/calibrate.c
    +++ b/init/calibrate.c
    @@ -66,7 +66,7 @@ static unsigned long __cpuinit calibrate_delay_direct(void)
    pre_start = 0;
    read_current_timer(&start);
    start_jiffies = jiffies;
    - while (jiffies <= (start_jiffies + 1)) {
    + while (time_before_eq(jiffies, start_jiffies + 1)) {
    pre_start = start;
    read_current_timer(&start);
    }
    @@ -74,8 +74,8 @@ static unsigned long __cpuinit calibrate_delay_direct(void)

    pre_end = 0;
    end = post_start;
    - while (jiffies <=
    - (start_jiffies + 1 + DELAY_CALIBRATION_TICKS)) {
    + while (time_before_eq(jiffies, start_jiffies + 1 +
    + DELAY_CALIBRATION_TICKS)) {
    pre_end = end;
    read_current_timer(&end);
    }
    --
    1.7.4.4


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