From 8707d8b8c0cbdf4441507f8dded194167da896c7 Mon Sep 17 00:00:00 2001 From: Paul Menage Date: Thu, 18 Oct 2007 23:40:22 -0700 Subject: Fix cpusets update_cpumask Cause writes to cpuset "cpus" file to update cpus_allowed for member tasks: - collect batches of tasks under tasklist_lock and then call set_cpus_allowed() on them outside the lock (since this can sleep). - add a simple generic priority heap type to allow efficient collection of batches of tasks to be processed without duplicating or missing any tasks in subsequent batches. - make "cpus" file update a no-op if the mask hasn't changed - fix race between update_cpumask() and sched_setaffinity() by making sched_setaffinity() post-check that it's not running on any cpus outside cpuset_cpus_allowed(). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Paul Menage Cc: Paul Jackson Cc: David Rientjes Cc: Nick Piggin Cc: Peter Zijlstra Cc: Balbir Singh Cc: Cedric Le Goater Cc: "Eric W. Biederman" Cc: Serge Hallyn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sched.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'kernel/sched.c') diff --git a/kernel/sched.c b/kernel/sched.c index 39d6354af489d..72a809a54d5ba 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4471,8 +4471,21 @@ long sched_setaffinity(pid_t pid, cpumask_t new_mask) cpus_allowed = cpuset_cpus_allowed(p); cpus_and(new_mask, new_mask, cpus_allowed); + again: retval = set_cpus_allowed(p, new_mask); + if (!retval) { + cpus_allowed = cpuset_cpus_allowed(p); + if (!cpus_subset(new_mask, cpus_allowed)) { + /* + * We must have raced with a concurrent cpuset + * update. Just reset the cpus_allowed to the + * cpuset's cpus_allowed + */ + new_mask = cpus_allowed; + goto again; + } + } out_unlock: put_task_struct(p); mutex_unlock(&sched_hotcpu_mutex); -- cgit v1.2.3