urcu-wait: move wait code into separate file

[urcu.git] / urcu-qsbr.c

diff --git a/urcu-qsbr.c b/urcu-qsbr.c
index 7f747ed5f9ce8ef133df3c2d026b8b76154e2e9e..d69138974722d881d9345a105f48a6c4870d8f45 100644 (file)
--- a/urcu-qsbr.c
+++ b/urcu-qsbr.c
@@ -44,6 +44,7 @@
 #include "urcu/tls-compat.h"
 
 #include "urcu-die.h"
+#include "urcu-wait.h"
 
 /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
 #undef _LGPL_SOURCE
@@ -79,24 +80,9 @@ DEFINE_URCU_TLS(unsigned int, rcu_rand_yield);
 
 static CDS_LIST_HEAD(registry);
 
-/*
- * Number of busy-loop attempts before waiting on futex for grace period
- * batching.
- */
-#define RCU_AWAKE_ATTEMPTS 1000
-
-enum adapt_wakeup_state {
-       /* AWAKE_WAITING is compared directly (futex compares it). */
-       AWAKE_WAITING =         0,
-       /* non-zero are used as masks. */
-       AWAKE_WAKEUP =          (1 << 0),
-       AWAKE_AWAKENED =        (1 << 1),
-       AWAKE_TEARDOWN =        (1 << 2),
-};
-
 struct gp_waiters_thread {
        struct cds_wfs_node node;
-       int32_t wait_futex;
+       struct urcu_wait wait;
 };
 
 /*
@@ -146,58 +132,6 @@ static void wait_gp(void)
                      NULL, NULL, 0);
 }
 
-/*
- * Note: urcu_adaptative_wake_up needs "value" to stay allocated
- * throughout its execution. In this scheme, the waiter owns the futex
- * memory, and we only allow it to free this memory when it receives the
- * AWAKE_TEARDOWN flag.
- */
-static void urcu_adaptative_wake_up(int32_t *value)
-{
-       cmm_smp_mb();
-       assert(uatomic_read(value) == AWAKE_WAITING);
-       uatomic_set(value, AWAKE_WAKEUP);
-       if (!(uatomic_read(value) & AWAKE_AWAKENED))
-               futex_noasync(value, FUTEX_WAKE, 1, NULL, NULL, 0);
-       /* Allow teardown of "value" memory. */
-       uatomic_or(value, AWAKE_TEARDOWN);
-}
-
-/*
- * Caller must initialize "value" to AWAKE_WAITING before passing its
- * memory to waker thread.
- */
-static void urcu_adaptative_busy_wait(int32_t *value)
-{
-       unsigned int i;
-
-       /* Load and test condition before read futex */
-       cmm_smp_rmb();
-       for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) {
-               if (uatomic_read(value) != AWAKE_WAITING)
-                       goto skip_futex_wait;
-               caa_cpu_relax();
-       }
-       futex_noasync(value, FUTEX_WAIT, AWAKE_WAITING, NULL, NULL, 0);
-skip_futex_wait:
-
-       /* Tell waker thread than we are awakened. */
-       uatomic_or(value, AWAKE_AWAKENED);
-
-       /*
-        * Wait until waker thread lets us know it's ok to tear down
-        * memory allocated for value.
-        */
-       for (i = 0; i < RCU_AWAKE_ATTEMPTS; i++) {
-               if (uatomic_read(value) & AWAKE_TEARDOWN)
-                       break;
-               caa_cpu_relax();
-       }
-       while (!(uatomic_read(value) & AWAKE_TEARDOWN))
-               poll(NULL, 0, 10);
-       assert(uatomic_read(value) & AWAKE_TEARDOWN);
-}
-
 static void wait_for_readers(struct cds_list_head *input_readers,
                        struct cds_list_head *cur_snap_readers,
                        struct cds_list_head *qsreaders)
@@ -305,10 +239,10 @@ void synchronize_rcu(void)
         * if we are the first thread added into the stack.
         */
        cds_wfs_node_init(&gp_waiters_thread.node);
-       gp_waiters_thread.wait_futex = AWAKE_WAITING;
+       urcu_wait_init(&gp_waiters_thread.wait);
        if (cds_wfs_push(&gp_waiters, &gp_waiters_node) != 0) {
                /* Not first in stack: will be awakened by another thread. */
-               urcu_adaptative_busy_wait(&gp_waiters_thread.wait_futex);
+               urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
                goto gp_end;
        }
 
@@ -384,7 +318,7 @@ out:
                                struct gp_waiters_thread, node);
                if (wt == &gp_waiters_thread)
                        continue;
-               urcu_adaptative_wake_up(&wt->wait_futex);
+               urcu_adaptative_wake_up(&wt->wait);
        }
 
 gp_end:
@@ -424,10 +358,10 @@ void synchronize_rcu(void)
         * if we are the first thread added into the stack.
         */
        cds_wfs_node_init(&gp_waiters_thread.node);
-       gp_waiters_thread.wait_futex = AWAKE_WAITING;
+       urcu_wait_init(&gp_waiters_thread.wait);
        if (cds_wfs_push(&gp_waiters, &gp_waiters_thread.node) != 0) {
                /* Not first in stack: will be awakened by another thread. */
-               urcu_adaptative_busy_wait(&gp_waiters_thread.wait_futex);
+               urcu_adaptative_busy_wait(&gp_waiters_thread.wait);
                goto gp_end;
        }
 
@@ -481,7 +415,7 @@ out:
                                struct gp_waiters_thread, node);
                if (wt == &gp_waiters_thread)
                        continue;
-               urcu_adaptative_wake_up(&wt->wait_futex);
+               urcu_adaptative_wake_up(&wt->wait);
        }
 
 gp_end: