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rcu_sync: Add CONFIG_PROVE_RCU checks

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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: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Oleg Nesterov 2015-08-21 19:42:50 +02:00 committed by Paul E. McKenney
parent 82e8c565be
commit 3a518b76af
2 changed files with 26 additions and 0 deletions
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6
include/linux/rcu_sync.h
View File

@ -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);

20
kernel/rcu/sync.c
View File

@ -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