From 6f7f02e78a75a09195d963e0392b195bc2d55c5c Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Tue, 8 May 2007 00:31:43 -0700 Subject: [PATCH] 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 Cc: Christoph Lameter Signed-off-by: Paul Menage Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpuset.c | 38 ++++++++++++++++++++++++++++++-------- 1 file changed, 30 insertions(+), 8 deletions(-) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index e6d002fc739..88b416dfbc7 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; } -- 2.20.1