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authorJack Steiner <steiner@sgi.com>2006-02-01 06:05:18 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-02-01 11:53:13 -0500
commit2f7016d917faef8f1e016b4a7bd7f594694480b6 (patch)
tree06aa6181a5609ad1e3815a08cf9a67df4ab08137
parent0f07496144c270f10d0ad06b70b9c9387d5527fd (diff)
[PATCH] sys_sched_getaffinity() & hotplug
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. 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 :-) Signed-off-by: Jack Steiner <steiner@sgi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Nathan Lynch <ntl@pobox.com> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/sched.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index ec7fd9cee306..f77f23f8f479 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4031,7 +4031,7 @@ long sched_getaffinity(pid_t pid, cpumask_t *mask)
4031 goto out_unlock; 4031 goto out_unlock;
4032 4032
4033 retval = 0; 4033 retval = 0;
4034 cpus_and(*mask, p->cpus_allowed, cpu_possible_map); 4034 cpus_and(*mask, p->cpus_allowed, cpu_online_map);
4035 4035
4036out_unlock: 4036out_unlock:
4037 read_unlock(&tasklist_lock); 4037 read_unlock(&tasklist_lock);