2.6.8.1: xtime value may become incorrect

[Vladimir Grouzdev]

   The xtime value may become incorrect when the
   update_wall_time(ticks) function is called with "ticks" > 1.
   In such a case, the xtime variable is updated multiple times
   inside the loop but it is normalized only once outside of
   the loop.

   This bug was reported at:

   http://bugme.osdl.org/show_bug.cgi?id=3403

   Patch to fix the problem:

diff -Nrca linux-2.6.8.1/kernel/timer.c linux-2.6.8.1-patched/kernel/timer.c
*** linux-2.6.8.1/kernel/timer.c    2004-08-14 12:56:00.000000000 +0200
--- linux-2.6.8.1-patched/kernel/timer.c    2004-09-27 
16:24:48.000000000 +0200
***************
*** 776,788 ****
     do {
         ticks--;
         update_wall_time_one_tick();
     } while (ticks);
-
-     if (xtime.tv_nsec >= 1000000000) {
-         xtime.tv_nsec -= 1000000000;
-         xtime.tv_sec++;
-         second_overflow();
-     }
 }

 static inline void do_process_times(struct task_struct *p,
--- 776,787 ----
     do {
         ticks--;
         update_wall_time_one_tick();
+         if (xtime.tv_nsec >= 1000000000) {
+             xtime.tv_nsec -= 1000000000;
+             xtime.tv_sec++;
+             second_overflow();
+         }
     } while (ticks);
 }

 static inline void do_process_times(struct task_struct *p,


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/