rcu_sync: Simplify rcu_sync using new rcu_sync_ops structure
This commit adds the new struct rcu_sync_ops which holds sync/call methods, and turns the function pointers in rcu_sync_struct into an array of struct rcu_sync_ops. This simplifies the "init" helpers by collapsing a switch statement and explicit multiple definitions into a simple assignment and a helper macro, respectively. 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>
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@ -26,6 +26,8 @@
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#include <linux/wait.h>
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#include <linux/rcupdate.h>
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enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
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/* Structure to mediate between updaters and fastpath-using readers. */
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struct rcu_sync {
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int gp_state;
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@ -35,43 +37,9 @@ struct rcu_sync {
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int cb_state;
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struct rcu_head cb_head;
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void (*sync)(void);
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void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
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enum rcu_sync_type gp_type;
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};
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#define ___RCU_SYNC_INIT(name) \
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.gp_state = 0, \
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.gp_count = 0, \
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.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
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.cb_state = 0
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#define __RCU_SCHED_SYNC_INIT(name) { \
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___RCU_SYNC_INIT(name), \
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.sync = synchronize_sched, \
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.call = call_rcu_sched, \
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}
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#define __RCU_BH_SYNC_INIT(name) { \
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___RCU_SYNC_INIT(name), \
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.sync = synchronize_rcu_bh, \
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.call = call_rcu_bh, \
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}
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#define __RCU_SYNC_INIT(name) { \
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___RCU_SYNC_INIT(name), \
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.sync = synchronize_rcu, \
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.call = call_rcu, \
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}
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#define DEFINE_RCU_SCHED_SYNC(name) \
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struct rcu_sync name = __RCU_SCHED_SYNC_INIT(name)
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#define DEFINE_RCU_BH_SYNC(name) \
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struct rcu_sync name = __RCU_BH_SYNC_INIT(name)
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#define DEFINE_RCU_SYNC(name) \
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struct rcu_sync name = __RCU_SYNC_INIT(name)
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/**
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* rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
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* @rsp: Pointer to rcu_sync structure to use for synchronization
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@ -85,10 +53,28 @@ static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
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return !rsp->gp_state; /* GP_IDLE */
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}
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enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
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extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
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extern void rcu_sync_enter(struct rcu_sync *);
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extern void rcu_sync_exit(struct rcu_sync *);
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#define __RCU_SYNC_INITIALIZER(name, type) { \
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.gp_state = 0, \
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.gp_count = 0, \
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.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
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.cb_state = 0, \
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.gp_type = type, \
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}
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#define __DEFINE_RCU_SYNC(name, type) \
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struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
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#define DEFINE_RCU_SYNC(name) \
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__DEFINE_RCU_SYNC(name, RCU_SYNC)
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#define DEFINE_RCU_SCHED_SYNC(name) \
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__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
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#define DEFINE_RCU_BH_SYNC(name) \
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__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
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#endif /* _LINUX_RCU_SYNC_H_ */
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@ -23,6 +23,24 @@
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#include <linux/rcu_sync.h>
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#include <linux/sched.h>
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static const struct {
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void (*sync)(void);
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void (*call)(struct rcu_head *, void (*)(struct rcu_head *));
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} gp_ops[] = {
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[RCU_SYNC] = {
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.sync = synchronize_rcu,
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.call = call_rcu,
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},
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[RCU_SCHED_SYNC] = {
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.sync = synchronize_sched,
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.call = call_rcu_sched,
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},
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[RCU_BH_SYNC] = {
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.sync = synchronize_rcu_bh,
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.call = call_rcu_bh,
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},
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};
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enum { GP_IDLE = 0, GP_PENDING, GP_PASSED };
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enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY };
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@ -37,23 +55,7 @@ void rcu_sync_init(struct rcu_sync *rsp, enum rcu_sync_type type)
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{
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memset(rsp, 0, sizeof(*rsp));
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init_waitqueue_head(&rsp->gp_wait);
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switch (type) {
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case RCU_SYNC:
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rsp->sync = synchronize_rcu;
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rsp->call = call_rcu;
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break;
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case RCU_SCHED_SYNC:
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rsp->sync = synchronize_sched;
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rsp->call = call_rcu_sched;
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break;
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case RCU_BH_SYNC:
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rsp->sync = synchronize_rcu_bh;
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rsp->call = call_rcu_bh;
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break;
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}
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rsp->gp_type = type;
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}
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/**
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@ -85,7 +87,7 @@ void rcu_sync_enter(struct rcu_sync *rsp)
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BUG_ON(need_wait && need_sync);
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if (need_sync) {
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rsp->sync();
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gp_ops[rsp->gp_type].sync();
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rsp->gp_state = GP_PASSED;
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wake_up_all(&rsp->gp_wait);
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} else if (need_wait) {
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@ -138,7 +140,7 @@ static void rcu_sync_func(struct rcu_head *rcu)
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* to catch a later GP.
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*/
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rsp->cb_state = CB_PENDING;
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rsp->call(&rsp->cb_head, rcu_sync_func);
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gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);
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} else {
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/*
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* We're at least a GP after rcu_sync_exit(); eveybody will now
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@ -166,7 +168,7 @@ void rcu_sync_exit(struct rcu_sync *rsp)
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if (!--rsp->gp_count) {
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if (rsp->cb_state == CB_IDLE) {
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rsp->cb_state = CB_PENDING;
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rsp->call(&rsp->cb_head, rcu_sync_func);
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gp_ops[rsp->gp_type].call(&rsp->cb_head, rcu_sync_func);
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} else if (rsp->cb_state == CB_PENDING) {
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rsp->cb_state = CB_REPLAY;
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}
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