[PATCH] fix schedstats null deref in sched_exec

[Nathan Lynch]

Oops, I meant to send this one with my original patchset.

In sched_exec, schedstat_inc will dereference a null pointer if no
domain is found with the SD_BALANCE_EXEC flag set.  This was exposed
during testing of the previous patches where cpus are temporarily
attached to a dummy domain without SD_BALANCE_EXEC set.

Signed-off-by: Nathan Lynch <nathanl@xxxxxxxxxxxxxx>


---


diff -puN kernel/sched.c~sched_exec-schedstats-fix kernel/sched.c
--- 2.6.9-rc1-bk12/kernel/sched.c~sched_exec-schedstats-fix	2004-09-06 02:14:05.000000000 -0500
+++ 2.6.9-rc1-bk12-nathanl/kernel/sched.c	2004-09-06 19:00:12.000000000 -0500
@@ -1727,8 +1727,8 @@ void sched_exec(void)
 		if (tmp->flags & SD_BALANCE_EXEC)
 			sd = tmp;
 
-	schedstat_inc(sd, sbe_attempts);
 	if (sd) {
+		schedstat_inc(sd, sbe_attempts);
 		new_cpu = find_idlest_cpu(current, this_cpu, sd);
 		if (new_cpu != this_cpu) {
 			schedstat_inc(sd, sbe_pushed);

_


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