hangcheck-timer: fix x86_32 bugs

drivers/char/hangcheck-timer.c is doubly broken.  When the overflown value
of TIMER_FREQ is abnormally low, it spams the syslog with KERN_CRIT
messages "Hangcheck: hangcheck value past margin!" But whether it happens
or not depends on HZ and lpj in a complex way.  People have hit it
occasionally as far as google search can tell.

First, the following line overflows unsigned long:

# define TIMER_FREQ (HZ*loops_per_jiffy)

Second, and more importantly, loops_per_jiffy has little to do with the
con= version from the the time scale of get_cycles() (aka rdtsc) to the
time scale of jiffies.

The attached patch resolves both of the problems.

Acked-by: Joel Becker <[email protected]>
Cc: john stultz <[email protected]>
Cc: Jan Glauber <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions