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Commit 3a518b76 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul E. McKenney
Browse files

rcu_sync: Add CONFIG_PROVE_RCU checks 



This commit validates that the caller of rcu_sync_is_idle() holds the
corresponding type of RCU read-side lock, but only in kernels built
with CONFIG_PROVE_RCU=y.  This validation is carried out via a new
rcu_sync_ops->held() method that is checked within rcu_sync_is_idle().

Note that although this does add code to the fast path, it only does so
in kernels built with CONFIG_PROVE_RCU=y.

Suggested-by: default avatar"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
parent 82e8c565

include/linux/rcu_sync.h

+6 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ struct rcu_sync { 
	enum rcu_sync_type	gp_type;

};



extern bool __rcu_sync_is_idle(struct rcu_sync *);



/**

 * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?

 * @rsp: Pointer to rcu_sync structure to use for synchronization
@@ -50,7 +52,11 @@ struct rcu_sync { 
 */

static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)

{

#ifdef CONFIG_PROVE_RCU

	return __rcu_sync_is_idle(rsp);

#else

	return !rsp->gp_state; /* GP_IDLE */

#endif

}



extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);

kernel/rcu/sync.c

+20 −0
Original line number Diff line number Diff line
@@ -23,21 +23,33 @@ 
#include <linux/rcu_sync.h>

#include <linux/sched.h>



#ifdef CONFIG_PROVE_RCU

#define __INIT_HELD(func)	.held = func,

#else

#define __INIT_HELD(func)

#endif



static const struct {

	void (*sync)(void);

	void (*call)(struct rcu_head *, void (*)(struct rcu_head *));

#ifdef CONFIG_PROVE_RCU

	int  (*held)(void);

#endif

} gp_ops[] = {

	[RCU_SYNC] = {

		.sync = synchronize_rcu,

		.call = call_rcu,

		__INIT_HELD(rcu_read_lock_held)

	},

	[RCU_SCHED_SYNC] = {

		.sync = synchronize_sched,

		.call = call_rcu_sched,

		__INIT_HELD(rcu_read_lock_sched_held)

	},

	[RCU_BH_SYNC] = {

		.sync = synchronize_rcu_bh,

		.call = call_rcu_bh,

		__INIT_HELD(rcu_read_lock_bh_held)

	},

};
@@ -46,6 +58,14 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY }; 


#define	rss_lock	gp_wait.lock



#ifdef CONFIG_PROVE_RCU

bool __rcu_sync_is_idle(struct rcu_sync *rsp)

{

	WARN_ON(!gp_ops[rsp->gp_type].held());

	return rsp->gp_state == GP_IDLE;

}

#endif



/**

 * rcu_sync_init() - Initialize an rcu_sync structure

 * @rsp: Pointer to rcu_sync structure to be initialized