Commit 994aeb7a authored Mar 20, 2019 by Joel Fernandes (Google) Committed by Ingo Molnar Apr 03, 2019

sched_domain: Annotate RCU pointers properly



The scheduler uses RCU API in various places to access sched_domain
pointers. These cause sparse errors as below.

Many new errors show up because of an annotation check I added to
rcu_assign_pointer(). Let us annotate the pointers correctly which also
will help sparse catch any potential future bugs.

This fixes the following sparse errors:

  rt.c:1681:9: error: incompatible types in comparison expression
  deadline.c:1904:9: error: incompatible types in comparison expression
  core.c:519:9: error: incompatible types in comparison expression
  core.c:1634:17: error: incompatible types in comparison expression
  fair.c:6193:14: error: incompatible types in comparison expression
  fair.c:9883:22: error: incompatible types in comparison expression
  fair.c:9897:9: error: incompatible types in comparison expression
  sched.h:1287:9: error: incompatible types in comparison expression
  topology.c:612:9: error: incompatible types in comparison expression
  topology.c:615:9: error: incompatible types in comparison expression
  sched.h:1300:9: error: incompatible types in comparison expression
  topology.c:618:9: error: incompatible types in comparison expression
  sched.h:1287:9: error: incompatible types in comparison expression
  topology.c:621:9: error: incompatible types in comparison expression
  sched.h:1300:9: error: incompatible types in comparison expression
  topology.c:624:9: error: incompatible types in comparison expression
  topology.c:671:9: error: incompatible types in comparison expression
  stats.c:45:17: error: incompatible types in comparison expression
  fair.c:5998:15: error: incompatible types in comparison expression
  fair.c:5989:15: error: incompatible types in comparison expression
  fair.c:5998:15: error: incompatible types in comparison expression
  fair.c:5989:15: error: incompatible types in comparison expression
  fair.c:6120:19: error: incompatible types in comparison expression
  fair.c:6506:14: error: incompatible types in comparison expression
  fair.c:6515:14: error: incompatible types in comparison expression
  fair.c:6623:9: error: incompatible types in comparison expression
  fair.c:5970:17: error: incompatible types in comparison expression
  fair.c:8642:21: error: incompatible types in comparison expression
  fair.c:9253:9: error: incompatible types in comparison expression
  fair.c:9331:9: error: incompatible types in comparison expression
  fair.c:9519:15: error: incompatible types in comparison expression
  fair.c:9533:14: error: incompatible types in comparison expression
  fair.c:9542:14: error: incompatible types in comparison expression
  fair.c:9567:14: error: incompatible types in comparison expression
  fair.c:9597:14: error: incompatible types in comparison expression
  fair.c:9421:16: error: incompatible types in comparison expression
  fair.c:9421:16: error: incompatible types in comparison expression

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ From an RCU perspective. ]
Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com
Cc: kernel-team@android.com
Link: https://lkml.kernel.org/r/20190321003426.160260-3-joel@joelfernandes.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent b10abd0a

include/linux/sched/topology.h

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -76,8 +76,8 @@ struct sched_domain_shared {

	struct sched_domain {		struct sched_domain {
	/* These fields must be setup */		/* These fields must be setup */
	struct sched_domain parent; / top domain must be null terminated */		struct sched_domain __rcu parent; / top domain must be null terminated */
	struct sched_domain child; / bottom domain must be null terminated */		struct sched_domain __rcu child; / bottom domain must be null terminated */
	struct sched_group groups; / the balancing groups of the domain */		struct sched_group groups; / the balancing groups of the domain */
	unsigned long min_interval; /* Minimum balance interval ms */		unsigned long min_interval; /* Minimum balance interval ms */
	unsigned long max_interval; /* Maximum balance interval ms */		unsigned long max_interval; /* Maximum balance interval ms */

kernel/sched/sched.h

+7 −7

Original line number	Original line	Diff line number	Diff line
	@@ -870,7 +870,7 @@ struct rq {

	#ifdef CONFIG_SMP		#ifdef CONFIG_SMP
	struct root_domain *rd;		struct root_domain *rd;
	struct sched_domain *sd;		struct sched_domain __rcu *sd;

	unsigned long cpu_capacity;		unsigned long cpu_capacity;
	unsigned long cpu_capacity_orig;		unsigned long cpu_capacity_orig;
	@@ -1324,13 +1324,13 @@ static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
	return sd;		return sd;
	}		}

	DECLARE_PER_CPU(struct sched_domain *, sd_llc);		DECLARE_PER_CPU(struct sched_domain __rcu *, sd_llc);
	DECLARE_PER_CPU(int, sd_llc_size);		DECLARE_PER_CPU(int, sd_llc_size);
	DECLARE_PER_CPU(int, sd_llc_id);		DECLARE_PER_CPU(int, sd_llc_id);
	DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);		DECLARE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
	DECLARE_PER_CPU(struct sched_domain *, sd_numa);		DECLARE_PER_CPU(struct sched_domain __rcu *, sd_numa);
	DECLARE_PER_CPU(struct sched_domain *, sd_asym_packing);		DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
	DECLARE_PER_CPU(struct sched_domain *, sd_asym_cpucapacity);		DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
	extern struct static_key_false sched_asym_cpucapacity;		extern struct static_key_false sched_asym_cpucapacity;

	struct sched_group_capacity {		struct sched_group_capacity {

kernel/sched/topology.c

+5 −5

Original line number	Original line	Diff line number	Diff line
	@@ -615,13 +615,13 @@ static void destroy_sched_domains(struct sched_domain *sd)
	* the cpumask of the domain), this allows us to quickly tell if		* the cpumask of the domain), this allows us to quickly tell if
	* two CPUs are in the same cache domain, see cpus_share_cache().		* two CPUs are in the same cache domain, see cpus_share_cache().
	*/		*/
	DEFINE_PER_CPU(struct sched_domain *, sd_llc);		DEFINE_PER_CPU(struct sched_domain __rcu *, sd_llc);
	DEFINE_PER_CPU(int, sd_llc_size);		DEFINE_PER_CPU(int, sd_llc_size);
	DEFINE_PER_CPU(int, sd_llc_id);		DEFINE_PER_CPU(int, sd_llc_id);
	DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);		DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
	DEFINE_PER_CPU(struct sched_domain *, sd_numa);		DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
	DEFINE_PER_CPU(struct sched_domain *, sd_asym_packing);		DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
	DEFINE_PER_CPU(struct sched_domain *, sd_asym_cpucapacity);		DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
	DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);		DEFINE_STATIC_KEY_FALSE(sched_asym_cpucapacity);

	static void update_top_cache_domain(int cpu)		static void update_top_cache_domain(int cpu)

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