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authorDavid Rientjes <rientjes@google.com>2007-05-08 00:31:43 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:15:14 -0700
commit6f7f02e78a75a09195d963e0392b195bc2d55c5c (patch)
treea0ead177a4faaafdfa400ff9de3c992603e42f4d /kernel/cpuset.c
parent0c28f287aa57e065116731c1e44bedcbc14fd53f (diff)
downloadlinux-6f7f02e78a75a09195d963e0392b195bc2d55c5c.tar.bz2
cpusets: allow empty {cpus,mems}_allowed to be set for unpopulated cpuset
You currently cannot remove all cpus or mems from cpus_allowed or mems_allowed of a cpuset. We now allow both if there are no attached tasks. Acked-by: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Paul Menage <menage@google.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r--kernel/cpuset.c38
1 files changed, 30 insertions, 8 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index e6d002fc7392..88b416dfbc72 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -821,11 +821,22 @@ static int update_cpumask(struct cpuset *cs, char *buf)
return -EACCES;
trialcs = *cs;
- retval = cpulist_parse(buf, trialcs.cpus_allowed);
- if (retval < 0)
- return retval;
+
+ /*
+ * We allow a cpuset's cpus_allowed to be empty; if it has attached
+ * tasks, we'll catch it later when we validate the change and return
+ * -ENOSPC.
+ */
+ if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+ cpus_clear(trialcs.cpus_allowed);
+ } else {
+ retval = cpulist_parse(buf, trialcs.cpus_allowed);
+ if (retval < 0)
+ return retval;
+ }
cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map);
- if (cpus_empty(trialcs.cpus_allowed))
+ /* cpus_allowed cannot be empty for a cpuset with attached tasks. */
+ if (atomic_read(&cs->count) && cpus_empty(trialcs.cpus_allowed))
return -ENOSPC;
retval = validate_change(cs, &trialcs);
if (retval < 0)
@@ -918,16 +929,27 @@ static int update_nodemask(struct cpuset *cs, char *buf)
return -EACCES;
trialcs = *cs;
- retval = nodelist_parse(buf, trialcs.mems_allowed);
- if (retval < 0)
- goto done;
+
+ /*
+ * We allow a cpuset's mems_allowed to be empty; if it has attached
+ * tasks, we'll catch it later when we validate the change and return
+ * -ENOSPC.
+ */
+ if (!buf[0] || (buf[0] == '\n' && !buf[1])) {
+ nodes_clear(trialcs.mems_allowed);
+ } else {
+ retval = nodelist_parse(buf, trialcs.mems_allowed);
+ if (retval < 0)
+ goto done;
+ }
nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map);
oldmem = cs->mems_allowed;
if (nodes_equal(oldmem, trialcs.mems_allowed)) {
retval = 0; /* Too easy - nothing to do */
goto done;
}
- if (nodes_empty(trialcs.mems_allowed)) {
+ /* mems_allowed cannot be empty for a cpuset with attached tasks. */
+ if (atomic_read(&cs->count) && nodes_empty(trialcs.mems_allowed)) {
retval = -ENOSPC;
goto done;
}