Change sched_getaffinity() so that it returns a bitmap that indicates the
legally schedulable cpus that a task is allowed to run on.
Without this patch, if CONFIG_HOTPLUG_CPU is enabled, sched_getaffinity()
unconditionally returns (at least on IA64) a mask with NR_CPUS bits set.
This conveys no useful infornmation except for a kernel compile option.
Signed-off-by: Jack Steiner <[email protected]>
Acked-by: Ingo Molnar <[email protected]>
---
This fixes a breakage we obseved running recent kernels. We have MPI jobs
that use sched_getaffinity() to determine where to place their threads.
Placing them on non-existant cpus is problematic :-)
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c 2006-01-28 10:13:01.834293691 -0600
+++ linux/kernel/sched.c 2006-01-29 07:15:11.217227453 -0600
@@ -4031,7 +4031,7 @@ long sched_getaffinity(pid_t pid, cpumas
goto out_unlock;
retval = 0;
- cpus_and(*mask, p->cpus_allowed, cpu_possible_map);
+ cpus_and(*mask, p->cpus_allowed, cpu_online_map);
out_unlock:
read_unlock(&tasklist_lock);
-
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