Fix: handle sys_futex() FUTEX_WAIT interrupted by signal

[urcu.git] / urcu / static / urcu-qsbr.h

diff --git a/urcu/static/urcu-qsbr.h b/urcu/static/urcu-qsbr.h
index ea5e13adebd5fae0374a5ad81693dd6cf46436c2..143d75a7e1e047f0ec2f81709f3ca39175debdab 100644 (file)
--- a/urcu/static/urcu-qsbr.h
+++ b/urcu/static/urcu-qsbr.h
@@ -68,63 +68,21 @@ enum rcu_state {
        RCU_READER_INACTIVE,
 };
 
-#ifdef DEBUG_YIELD
-#include <sched.h>
-#include <time.h>
-#include <pthread.h>
-#include <unistd.h>
-
-#define RCU_YIELD_READ         (1 << 0)
-#define RCU_YIELD_WRITE        (1 << 1)
-
-/* maximum sleep delay, in us */
-#define MAX_SLEEP 50
-
-extern unsigned int rcu_yield_active;
-extern DECLARE_URCU_TLS(unsigned int, rcu_rand_yield);
-
-static inline void rcu_debug_yield_read(void)
-{
-       if (rcu_yield_active & RCU_YIELD_READ)
-               if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1)
-                       usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP);
-}
-
-static inline void rcu_debug_yield_write(void)
-{
-       if (rcu_yield_active & RCU_YIELD_WRITE)
-               if (rand_r(&URCU_TLS(rcu_rand_yield)) & 0x1)
-                       usleep(rand_r(&URCU_TLS(rcu_rand_yield)) % MAX_SLEEP);
-}
-
-static inline void rcu_debug_yield_init(void)
-{
-       URCU_TLS(rcu_rand_yield) = time(NULL) ^ (unsigned long) pthread_self();
-}
-#else
-static inline void rcu_debug_yield_read(void)
-{
-}
-
-static inline void rcu_debug_yield_write(void)
-{
-}
-
-static inline void rcu_debug_yield_init(void)
-{
-
-}
-#endif
-
 #define RCU_GP_ONLINE          (1UL << 0)
 #define RCU_GP_CTR             (1UL << 1)
 
-/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
- */
-extern unsigned long rcu_gp_ctr;
+struct rcu_gp {
+       /*
+        * Global quiescent period counter with low-order bits unused.
+        * Using a int rather than a char to eliminate false register
+        * dependencies causing stalls on some architectures.
+        */
+       unsigned long ctr;
+
+       int32_t futex;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
+extern struct rcu_gp rcu_gp;
 
 struct rcu_reader {
        /* Data used by both reader and synchronize_rcu() */
@@ -137,8 +95,6 @@ struct rcu_reader {
 
 extern DECLARE_URCU_TLS(struct rcu_reader, rcu_reader);
 
-extern int32_t rcu_gp_futex;
-
 /*
  * Wake-up waiting synchronize_rcu(). Called from many concurrent threads.
  */
@@ -147,11 +103,16 @@ static inline void wake_up_gp(void)
        if (caa_unlikely(_CMM_LOAD_SHARED(URCU_TLS(rcu_reader).waiting))) {
                _CMM_STORE_SHARED(URCU_TLS(rcu_reader).waiting, 0);
                cmm_smp_mb();
-               if (uatomic_read(&rcu_gp_futex) != -1)
+               if (uatomic_read(&rcu_gp.futex) != -1)
                        return;
-               uatomic_set(&rcu_gp_futex, 0);
-               futex_noasync(&rcu_gp_futex, FUTEX_WAKE, 1,
-                     NULL, NULL, 0);
+               uatomic_set(&rcu_gp.futex, 0);
+               /*
+                * Ignoring return value until we can make this function
+                * return something (because urcu_die() is not publicly
+                * exposed).
+                */
+               (void) futex_noasync(&rcu_gp.futex, FUTEX_WAKE, 1,
+                               NULL, NULL, 0);
        }
 }
 
@@ -162,7 +123,7 @@ static inline enum rcu_state rcu_reader_state(unsigned long *ctr)
        v = CMM_LOAD_SHARED(*ctr);
        if (!v)
                return RCU_READER_INACTIVE;
-       if (v == rcu_gp_ctr)
+       if (v == rcu_gp.ctr)
                return RCU_READER_ACTIVE_CURRENT;
        return RCU_READER_ACTIVE_OLD;
 }
@@ -228,7 +189,7 @@ static inline void _rcu_quiescent_state_update_and_wakeup(unsigned long gp_ctr)
  * to be invoked directly from non-LGPL code.
  *
  * We skip the memory barriers and gp store if our local ctr already
- * matches the global rcu_gp_ctr value: this is OK because a prior
+ * matches the global rcu_gp.ctr value: this is OK because a prior
  * _rcu_quiescent_state() or _rcu_thread_online() already updated it
  * within our thread, so we have no quiescent state to report.
  */
@@ -236,7 +197,7 @@ static inline void _rcu_quiescent_state(void)
 {
        unsigned long gp_ctr;
 
-       if ((gp_ctr = CMM_LOAD_SHARED(rcu_gp_ctr)) == URCU_TLS(rcu_reader).ctr)
+       if ((gp_ctr = CMM_LOAD_SHARED(rcu_gp.ctr)) == URCU_TLS(rcu_reader).ctr)
                return;
        _rcu_quiescent_state_update_and_wakeup(gp_ctr);
 }
@@ -269,7 +230,7 @@ static inline void _rcu_thread_offline(void)
 static inline void _rcu_thread_online(void)
 {
        cmm_barrier();  /* Ensure the compiler does not reorder us with mutex */
-       _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, CMM_LOAD_SHARED(rcu_gp_ctr));
+       _CMM_STORE_SHARED(URCU_TLS(rcu_reader).ctr, CMM_LOAD_SHARED(rcu_gp.ctr));
        cmm_smp_mb();
 }