From: Mathieu Desnoyers Date: Fri, 6 Feb 2009 01:04:03 +0000 (-0500) Subject: runs X-Git-Tag: v0.1~330 X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=41718ff94c4a07cb5f56d68084267798e471d1b1;p=urcu.git runs --- diff --git a/test_urcu.c b/test_urcu.c index f9b0e86..8212dfc 100644 --- a/test_urcu.c +++ b/test_urcu.c @@ -1,27 +1,50 @@ #include #include #include +#include #include #include #include #include +#include #include "urcu.h" -#define NR_READ 10 -#define NR_WRITE 4 +struct test_array { + int a; + int b; + char c[200]; +}; + +static struct test_array *test_rcu_pointer; + +#define NR_READ 1000 +#define NR_WRITE 50 void *thr_reader(void *arg) { + int qparity, i; + struct test_array *local_ptr; + printf("thread %s, thread id : %lu, pid %lu\n", "reader", pthread_self(), getpid()); sleep(2); urcu_register_thread(); - + for (i = 0; i < 1000; i++) { + qparity = rcu_read_lock(); + local_ptr = rcu_dereference(test_rcu_pointer); + if (local_ptr) { + assert(local_ptr->a == 8); + assert(local_ptr->b == 12); + assert(local_ptr->c[55] == 2); + } + rcu_read_unlock(qparity); + } urcu_unregister_thread(); + return ((void*)1); } @@ -29,12 +52,28 @@ void *thr_reader(void *arg) void *thr_writer(void *arg) { int i; + struct test_array *new, *old; printf("thread %s, thread id : %lu, pid %lu\n", "writer", pthread_self(), getpid()); sleep(2); for (i = 0; i < 1000; i++) { + rcu_write_lock(); + new = malloc(sizeof(struct test_array)); + old = test_rcu_pointer; + if (old) { + assert(old->a == 8); + assert(old->b == 12); + assert(old->c[55] == 2); + } + assert(new->a = 8); + assert(new->b = 12); + assert(new->c[55] = 2); + old = urcu_publish_content(&test_rcu_pointer, new); + rcu_write_unlock(); + /* can be done after unlock */ + free(old); } return ((void*)2); diff --git a/urcu.c b/urcu.c index c55a5a2..7e79207 100644 --- a/urcu.c +++ b/urcu.c @@ -26,6 +26,27 @@ static struct reader_data *reader_data; static int num_readers, alloc_readers; static int sig_done; +void rcu_write_lock(void) +{ + int ret; + ret = pthread_mutex_lock(&urcu_mutex); + if (ret) { + perror("Error in pthread mutex lock"); + exit(-1); + } +} + +void rcu_write_unlock(void) +{ + int ret; + + ret = pthread_mutex_unlock(&urcu_mutex); + if (ret) { + perror("Error in pthread mutex unlock"); + exit(-1); + } +} + /* * called with urcu_mutex held. */ @@ -84,18 +105,13 @@ void wait_for_quiescent_state(int parity) /* * Return old pointer, OK to free, no more reference exist. + * Called under rcu_write_lock. */ void *urcu_publish_content(void **ptr, void *new) { int ret, prev_parity; void *oldptr; - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex lock"); - exit(-1); - } - /* * We can publish the new pointer before we change the current qparity. * Readers seeing the new pointer while being in the previous qparity @@ -121,11 +137,6 @@ void *urcu_publish_content(void **ptr, void *new) * Deleting old data is ok ! */ - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex lock"); - exit(-1); - } return oldptr; } @@ -179,44 +190,17 @@ void urcu_remove_reader(pthread_t id) void urcu_register_thread(void) { - pthread_t self = pthread_self(); - int ret; - - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex lock"); - exit(-1); - } - - urcu_add_reader(self); - - - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex unlock"); - exit(-1); - } + rcu_write_lock(); + urcu_add_reader(pthread_self()); + rcu_write_unlock(); } void urcu_unregister_thread(void) { pthread_t self = pthread_self(); - int ret; - - ret = pthread_mutex_lock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex lock"); - exit(-1); - } - - urcu_remove_reader(self); - - ret = pthread_mutex_unlock(&urcu_mutex); - if (ret) { - perror("Error in pthread mutex unlock"); - exit(-1); - } - + rcu_write_lock(); + urcu_remove_reader(pthread_self()); + rcu_write_unlock(); } void sigurcu_handler(int signo, siginfo_t *siginfo, void *context) diff --git a/urcu.h b/urcu.h index 363021d..bee7715 100644 --- a/urcu.h +++ b/urcu.h @@ -21,6 +21,36 @@ static inline void atomic_inc(int *v) /* Nop everywhere except on alpha. */ #define smp_read_barrier_depends() +/* + * Prevent the compiler from merging or refetching accesses. The compiler + * is also forbidden from reordering successive instances of ACCESS_ONCE(), + * but only when the compiler is aware of some particular ordering. One way + * to make the compiler aware of ordering is to put the two invocations of + * ACCESS_ONCE() in different C statements. + * + * This macro does absolutely -nothing- to prevent the CPU from reordering, + * merging, or refetching absolutely anything at any time. Its main intended + * use is to mediate communication between process-level code and irq/NMI + * handlers, all running on the same CPU. + */ +#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) + +/** + * rcu_dereference - fetch an RCU-protected pointer in an + * RCU read-side critical section. This pointer may later + * be safely dereferenced. + * + * Inserts memory barriers on architectures that require them + * (currently only the Alpha), and, more importantly, documents + * exactly which pointers are protected by RCU. + */ + +#define rcu_dereference(p) ({ \ + typeof(p) _________p1 = ACCESS_ONCE(p); \ + smp_read_barrier_depends(); \ + (_________p1); \ + }) + #define SIGURCU SIGUSR1 /* Global quiescent period parity */ @@ -58,6 +88,9 @@ static inline void rcu_read_unlock(int urcu_parity) urcu_active_readers[urcu_parity]--; } +extern void rcu_write_lock(void); +extern void rcu_write_unlock(void); + extern void *urcu_publish_content(void **ptr, void *new); /*