X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu-bp.c;h=8207a4120ffd6b0790939e0ee176e064198704fe;hp=08b4b55d46b97a353f177fc38114a8f350ae43f5;hb=882f335739b978d1c55be2faeed077f315afe5d7;hpb=79d5479e9f6dfe097fc24b0ddf2fe7fd1ba0f43b diff --git a/urcu-bp.c b/urcu-bp.c index 08b4b55..8207a41 100644 --- a/urcu-bp.c +++ b/urcu-bp.c @@ -36,10 +36,13 @@ #include #include -#include "urcu/wfqueue.h" +#include "urcu/wfcqueue.h" #include "urcu/map/urcu-bp.h" #include "urcu/static/urcu-bp.h" #include "urcu-pointer.h" +#include "urcu/tls-compat.h" + +#include "urcu-die.h" /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ #undef _LGPL_SOURCE @@ -50,7 +53,14 @@ #define MAP_ANONYMOUS MAP_ANON #endif -#ifndef __linux__ +#ifdef __linux__ +static +void *mremap_wrapper(void *old_address, size_t old_size, + size_t new_size, int flags) +{ + return mremap(old_address, old_size, new_size, flags); +} +#else #define MREMAP_MAYMOVE 1 #define MREMAP_FIXED 2 @@ -59,7 +69,9 @@ * mremap wrapper for non-Linux systems. Maps a RW, anonymous private mapping. * This is not generic. */ -void *mremap(void *old_address, size_t old_size, size_t new_size, int flags) +static +void *mremap_wrapper(void *old_address, size_t old_size, + size_t new_size, int flags) { void *new_address; @@ -93,8 +105,8 @@ void __attribute__((destructor)) rcu_bp_exit(void); static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; #ifdef DEBUG_YIELD -unsigned int yield_active; -unsigned int __thread rand_yield; +unsigned int rcu_yield_active; +DEFINE_URCU_TLS(unsigned int, rcu_rand_yield); #endif /* @@ -103,13 +115,13 @@ unsigned int __thread rand_yield; * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path. * Written to only by writer with mutex taken. Read by both writer and readers. */ -long rcu_gp_ctr = RCU_GP_COUNT; +unsigned long rcu_gp_ctr = RCU_GP_COUNT; /* * Pointer to registry elements. Written to only by each individual reader. Read * by both the reader and the writers. */ -struct rcu_reader __thread *rcu_reader; +DEFINE_URCU_TLS(struct rcu_reader *, rcu_reader); static CDS_LIST_HEAD(registry); @@ -132,17 +144,12 @@ static void mutex_lock(pthread_mutex_t *mutex) #ifndef DISTRUST_SIGNALS_EXTREME ret = pthread_mutex_lock(mutex); - if (ret) { - perror("Error in pthread mutex lock"); - exit(-1); - } + if (ret) + urcu_die(ret); #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ while ((ret = pthread_mutex_trylock(mutex)) != 0) { - if (ret != EBUSY && ret != EINTR) { - printf("ret = %d, errno = %d\n", ret, errno); - perror("Error in pthread mutex lock"); - exit(-1); - } + if (ret != EBUSY && ret != EINTR) + urcu_die(ret); poll(NULL,0,10); } #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ @@ -153,46 +160,48 @@ static void mutex_unlock(pthread_mutex_t *mutex) int ret; ret = pthread_mutex_unlock(mutex); - if (ret) { - perror("Error in pthread mutex unlock"); - exit(-1); - } + if (ret) + urcu_die(ret); } -void update_counter_and_wait(void) +static void wait_for_readers(struct cds_list_head *input_readers, + struct cds_list_head *cur_snap_readers, + struct cds_list_head *qsreaders) { - CDS_LIST_HEAD(qsreaders); int wait_loops = 0; struct rcu_reader *index, *tmp; - /* Switch parity: 0 -> 1, 1 -> 0 */ - 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 CMM_STORE_SHARED and CMM_LOAD_SHARED. - */ - - /* - * 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. - */ - cmm_smp_mb(); - - /* - * Wait for each thread rcu_reader.ctr count to become 0. + * Wait for each thread URCU_TLS(rcu_reader).ctr to either + * indicate quiescence (not nested), or observe the current + * rcu_gp_ctr value. */ for (;;) { wait_loops++; - cds_list_for_each_entry_safe(index, tmp, ®istry, node) { - if (!rcu_old_gp_ongoing(&index->ctr)) - cds_list_move(&index->node, &qsreaders); + cds_list_for_each_entry_safe(index, tmp, input_readers, node) { + switch (rcu_reader_state(&index->ctr)) { + case RCU_READER_ACTIVE_CURRENT: + if (cur_snap_readers) { + cds_list_move(&index->node, + cur_snap_readers); + break; + } + /* Fall-through */ + case RCU_READER_INACTIVE: + cds_list_move(&index->node, qsreaders); + break; + case RCU_READER_ACTIVE_OLD: + /* + * Old snapshot. Leaving node in + * input_readers will make us busy-loop + * until the snapshot becomes current or + * the reader becomes inactive. + */ + break; + } } - if (cds_list_empty(®istry)) { + if (cds_list_empty(input_readers)) { break; } else { if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) @@ -201,12 +210,12 @@ void update_counter_and_wait(void) caa_cpu_relax(); } } - /* put back the reader list in the registry */ - cds_list_splice(&qsreaders, ®istry); } void synchronize_rcu(void) { + CDS_LIST_HEAD(cur_snap_readers); + CDS_LIST_HEAD(qsreaders); sigset_t newmask, oldmask; int ret; @@ -229,9 +238,9 @@ void synchronize_rcu(void) rcu_gc_registry(); /* - * Wait for previous parity to be empty of readers. + * Wait for readers to observe original parity or be quiescent. */ - update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */ + wait_for_readers(®istry, &cur_snap_readers, &qsreaders); /* * Adding a cmm_smp_mb() which is _not_ formally required, but makes the @@ -240,10 +249,32 @@ void synchronize_rcu(void) */ cmm_smp_mb(); + /* Switch parity: 0 -> 1, 1 -> 0 */ + CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE); + /* - * Wait for previous parity to be empty of readers. + * 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 CMM_STORE_SHARED and CMM_LOAD_SHARED. */ - update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */ + + /* + * 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. + */ + cmm_smp_mb(); + + /* + * Wait for readers to observe new parity or be quiescent. + */ + wait_for_readers(&cur_snap_readers, NULL, &qsreaders); + + /* + * Put quiescent reader list back into registry. + */ + cds_list_splice(&qsreaders, ®istry); /* * Finish waiting for reader threads before letting the old ptr being @@ -270,6 +301,11 @@ void rcu_read_unlock(void) _rcu_read_unlock(); } +int rcu_read_ongoing(void) +{ + return _rcu_read_ongoing(); +} + /* * only grow for now. */ @@ -283,8 +319,8 @@ static void resize_arena(struct registry_arena *arena, size_t len) MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); else - new_arena = mremap(arena->p, arena->len, - len, MREMAP_MAYMOVE); + new_arena = mremap_wrapper(arena->p, arena->len, + len, MREMAP_MAYMOVE); assert(new_arena != MAP_FAILED); /* @@ -322,7 +358,7 @@ static void add_thread(void) rcu_reader_reg->tid = pthread_self(); assert(rcu_reader_reg->ctr == 0); cds_list_add(&rcu_reader_reg->node, ®istry); - rcu_reader = rcu_reader_reg; + URCU_TLS(rcu_reader) = rcu_reader_reg; } /* Called with signals off and mutex locked */ @@ -363,7 +399,7 @@ void rcu_bp_register(void) /* * Check if a signal concurrently registered our thread since * the check in rcu_read_lock(). */ - if (rcu_reader) + if (URCU_TLS(rcu_reader)) goto end; mutex_lock(&rcu_gp_lock); @@ -429,7 +465,8 @@ void *rcu_dereference_sym_bp(void *p) void *rcu_set_pointer_sym_bp(void **p, void *v) { cmm_wmb(); - return uatomic_set(p, v); + uatomic_set(p, v); + return v; } void *rcu_xchg_pointer_sym_bp(void **p, void *v)