tree d5433cf6b0a57b72b0220ff8e1d89ceca6fbd49c
parent f16a5e347835c6a0ba958535cf6e6c89d50463b8
author Thomas Gleixner <tglx@linutronix.de> 1274813010 +0200
committer Thomas Gleixner <tglx@linutronix.de> 1274814468 +0200

timers: Fix slack calculation really

commit f00e047ef (timers: Fix slack calculation for expired timers)
fixed the issue of slack on expired timers only partially. Linus
noticed that jiffies is volatile so it is reloaded twice, which
generates bad code.

But its worse. This can defeat the time_after() check if jiffies are
incremented between time_after() and the slack calculation.

Fix it by reading jiffies into a local variable, which prevents the
compiler from loading it twice. While at it make the > -1 check into
>= 0 which is easier to read.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>