[PATCH v2 05/10] cpuset: re-structure update_cpumask() a bit

From: Li Zefan
Date: Wed Jun 05 2013 - 05:17:03 EST


Check if cpus_allowed is to be changed before calling validate_change().

This won't change any behavior, but later it will allow us to do this:

# mkdir /cpuset/child
# echo $$ > /cpuset/child/tasks /* empty cpuset */
# echo > /cpuset/child/cpuset.cpus /* do nothing, won't fail */

Without this patch, the last operation will fail.

Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
---
kernel/cpuset.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 51f8e1d..535dce6 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -856,14 +856,15 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
if (!cpumask_subset(trialcs->cpus_allowed, cpu_active_mask))
return -EINVAL;
}
- retval = validate_change(cs, trialcs);
- if (retval < 0)
- return retval;

/* Nothing to do if the cpus didn't change */
if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
return 0;

+ retval = validate_change(cs, trialcs);
+ if (retval < 0)
+ return retval;
+
retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
if (retval)
return retval;
--
1.8.0.2
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