From 2f7016d917faef8f1e016b4a7bd7f594694480b6 Mon Sep 17 00:00:00 2001 From: Jack Steiner Date: Wed, 1 Feb 2006 03:05:18 -0800 Subject: [PATCH] [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 Acked-by: Ingo Molnar Cc: Nathan Lynch Cc: Paul Jackson Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched.c b/kernel/sched.c index ec7fd9cee3..f77f23f8f4 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4031,7 +4031,7 @@ long sched_getaffinity(pid_t pid, cpumask_t *mask) 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); -- 2.39.5