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cgroup/cpuset: Change cpuset_rwsem and hotplug lock order

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cpuset_rwsem is going to be acquired from sched_setscheduler() with a
following patch. There are however paths (e.g., spawn_ksoftirqd) in
which sched_scheduler() is eventually called while holding hotplug lock;
this creates a dependecy between hotplug lock (to be always acquired
first) and cpuset_rwsem (to be always acquired after hotplug lock).

Fix paths which currently take the two locks in the wrong order (after
a following patch is applied).

Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bristot@redhat.com
Cc: claudio@evidence.eu.com
Cc: lizefan@huawei.com
Cc: longman@redhat.com
Cc: luca.abeni@santannapisa.it
Cc: mathieu.poirier@linaro.org
Cc: rostedt@goodmis.org
Cc: tj@kernel.org
Cc: tommaso.cucinotta@santannapisa.it
Link: https://lkml.kernel.org/r/20190719140000.31694-7-juri.lelli@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Juri Lelli
2019-07-19 15:59:58 +02:00
committed by Ingo Molnar
parent 1243dc518c
commit d74b27d63a
2 changed files with 21 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
include/linux/cpuset.h
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@@ -40,14 +40,14 @@ static inline bool cpusets_enabled(void)
static inline void cpuset_inc(void)
{
static_branch_inc(&cpusets_pre_enable_key);
static_branch_inc(&cpusets_enabled_key);
static_branch_inc_cpuslocked(&cpusets_pre_enable_key);
static_branch_inc_cpuslocked(&cpusets_enabled_key);
}
static inline void cpuset_dec(void)
{
static_branch_dec(&cpusets_enabled_key);
static_branch_dec(&cpusets_pre_enable_key);
static_branch_dec_cpuslocked(&cpusets_enabled_key);
static_branch_dec_cpuslocked(&cpusets_pre_enable_key);
}
extern int cpuset_init(void);