X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu-bp.c;h=14b200129fe42656ae11e178aa0d3c6442f26061;hp=1b0bd6950da04533c35bf00a5c131ac4da3e470b;hb=0376e7b2f8d26778ebc4750b34e718c062c92764;hpb=32c15e4e6fa2c368f4649d904c91e4293a1193e3 diff --git a/urcu-bp.c b/urcu-bp.c index 1b0bd69..14b2001 100644 --- a/urcu-bp.c +++ b/urcu-bp.c @@ -3,7 +3,7 @@ * * Userspace RCU library, "bulletproof" version. * - * Copyright (c) 2009 Mathieu Desnoyers + * Copyright (c) 2009 Mathieu Desnoyers * Copyright (c) 2009 Paul E. McKenney, IBM Corporation. * * This library is free software; you can redistribute it and/or @@ -35,6 +35,8 @@ #include #include +#include "urcu-bp-map.h" + #include "urcu-bp-static.h" /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ #include "urcu-bp.h" @@ -66,7 +68,7 @@ long rcu_gp_ctr = RCU_GP_COUNT; */ struct rcu_reader __thread *rcu_reader; -static LIST_HEAD(registry); +static CDS_LIST_HEAD(registry); struct registry_arena { void *p; @@ -76,6 +78,9 @@ struct registry_arena { static struct registry_arena registry_arena; +/* Saved fork signal mask, protected by rcu_gp_lock */ +static sigset_t saved_fork_signal_mask; + static void rcu_gc_registry(void); static void mutex_lock(pthread_mutex_t *mutex) @@ -95,11 +100,6 @@ static void mutex_lock(pthread_mutex_t *mutex) perror("Error in pthread mutex lock"); exit(-1); } - if (rcu_reader.need_mb) { - smp_mb(); - rcu_reader.need_mb = 0; - smp_mb(); - } poll(NULL,0,10); } #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ @@ -118,48 +118,48 @@ static void mutex_unlock(pthread_mutex_t *mutex) void update_counter_and_wait(void) { - LIST_HEAD(qsreaders); + CDS_LIST_HEAD(qsreaders); int wait_loops = 0; struct rcu_reader *index, *tmp; /* Switch parity: 0 -> 1, 1 -> 0 */ - STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE); + CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE); /* * Must commit qparity update to memory before waiting for other parity * quiescent state. Failure to do so could result in the writer waiting * forever while new readers are always accessing data (no progress). - * Ensured by STORE_SHARED and LOAD_SHARED. + * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED. */ /* - * Adding a smp_mb() which is _not_ formally required, but makes the + * Adding a cmm_smp_mb() which is _not_ formally required, but makes the * model easier to understand. It does not have a big performance impact * anyway, given this is the write-side. */ - smp_mb(); + cmm_smp_mb(); /* * Wait for each thread rcu_reader.ctr count to become 0. */ for (;;) { wait_loops++; - list_for_each_entry_safe(index, tmp, ®istry, head) { + cds_list_for_each_entry_safe(index, tmp, ®istry, node) { if (!rcu_old_gp_ongoing(&index->ctr)) - list_move(&index->head, &qsreaders); + cds_list_move(&index->node, &qsreaders); } - if (list_empty(®istry)) { + if (cds_list_empty(®istry)) { break; } else { if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) usleep(RCU_SLEEP_DELAY); else - cpu_relax(); + caa_cpu_relax(); } } /* put back the reader list in the registry */ - list_splice(&qsreaders, ®istry); + cds_list_splice(&qsreaders, ®istry); } void synchronize_rcu(void) @@ -174,13 +174,13 @@ void synchronize_rcu(void) mutex_lock(&rcu_gp_lock); - if (list_empty(®istry)) + if (cds_list_empty(®istry)) goto out; /* All threads should read qparity before accessing data structure * where new ptr points to. */ /* Write new ptr before changing the qparity */ - smp_mb(); + cmm_smp_mb(); /* Remove old registry elements */ rcu_gc_registry(); @@ -191,11 +191,11 @@ void synchronize_rcu(void) update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */ /* - * Adding a smp_mb() which is _not_ formally required, but makes the + * Adding a cmm_smp_mb() which is _not_ formally required, but makes the * model easier to understand. It does not have a big performance impact * anyway, given this is the write-side. */ - smp_mb(); + cmm_smp_mb(); /* * Wait for previous parity to be empty of readers. @@ -206,7 +206,7 @@ void synchronize_rcu(void) * Finish waiting for reader threads before letting the old ptr being * freed. */ - smp_mb(); + cmm_smp_mb(); out: mutex_unlock(&rcu_gp_lock); ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); @@ -279,7 +279,7 @@ static void add_thread(void) /* Add to registry */ rcu_reader_reg->tid = pthread_self(); assert(rcu_reader_reg->ctr == 0); - list_add(&rcu_reader_reg->head, ®istry); + cds_list_add(&rcu_reader_reg->node, ®istry); rcu_reader = rcu_reader_reg; } @@ -299,7 +299,8 @@ static void rcu_gc_registry(void) ret = pthread_kill(tid, 0); assert(ret != EINVAL); if (ret == ESRCH) { - list_del(&rcu_reader_reg->head); + cds_list_del(&rcu_reader_reg->node); + rcu_reader_reg->ctr = 0; rcu_reader_reg->alloc = 0; registry_arena.used -= sizeof(struct rcu_reader); } @@ -335,3 +336,47 @@ void rcu_bp_exit() { munmap(registry_arena.p, registry_arena.len); } + +/* + * Holding the rcu_gp_lock across fork will make sure we fork() don't race with + * a concurrent thread executing with this same lock held. This ensures that the + * registry is in a coherent state in the child. + */ +void rcu_bp_before_fork(void) +{ + sigset_t newmask, oldmask; + int ret; + + ret = sigemptyset(&newmask); + assert(!ret); + ret = pthread_sigmask(SIG_SETMASK, &newmask, &oldmask); + assert(!ret); + mutex_lock(&rcu_gp_lock); + saved_fork_signal_mask = oldmask; +} + +void rcu_bp_after_fork_parent(void) +{ + sigset_t oldmask; + int ret; + + oldmask = saved_fork_signal_mask; + mutex_unlock(&rcu_gp_lock); + ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); + assert(!ret); +} + +void rcu_bp_after_fork_child(void) +{ + sigset_t oldmask; + int ret; + + rcu_gc_registry(); + oldmask = saved_fork_signal_mask; + mutex_unlock(&rcu_gp_lock); + ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); + assert(!ret); +} + +#include "urcu-call-rcu-impl.h" +#include "urcu-defer-impl.h"