Fix: move wait loop increment before first conditional block

[urcu.git] / urcu.c

diff --git a/urcu.c b/urcu.c
index a016bbda89db8ca970014728f24b24d738fb4464..ae3490f7cb2cdc1f7cdb1d26f77c0ee22620e9eb 100644 (file)
--- a/urcu.c
+++ b/urcu.c
@@ -53,9 +53,9 @@
 /*
  * If a reader is really non-cooperative and refuses to commit its
  * rcu_active_readers count to memory (there is no barrier in the reader
- * per-se), kick it after a few loops waiting for it.
+ * per-se), kick it after 10 loops waiting for it.
  */
-#define KICK_READER_LOOPS 10000
+#define KICK_READER_LOOPS      10
 
 /*
  * Active attempts to check for reader Q.S. before calling futex().
@@ -230,8 +230,11 @@ static void wait_for_readers(struct cds_list_head *input_readers,
                        struct cds_list_head *cur_snap_readers,
                        struct cds_list_head *qsreaders)
 {
-       int wait_loops = 0;
+       unsigned int wait_loops = 0;
        struct rcu_reader *index, *tmp;
+#ifdef HAS_INCOHERENT_CACHES
+       unsigned int wait_gp_loops = 0;
+#endif /* HAS_INCOHERENT_CACHES */
 
        /*
         * Wait for each thread URCU_TLS(rcu_reader).ctr to either
@@ -239,8 +242,9 @@ static void wait_for_readers(struct cds_list_head *input_readers,
         * rcu_gp.ctr value.
         */
        for (;;) {
-               wait_loops++;
-               if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+               if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
+                       wait_loops++;
+               if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                        uatomic_dec(&rcu_gp.futex);
                        /* Write futex before read reader_gp */
                        smp_mb_master(RCU_MB_GROUP);
@@ -271,14 +275,14 @@ static void wait_for_readers(struct cds_list_head *input_readers,
 
 #ifndef HAS_INCOHERENT_CACHES
                if (cds_list_empty(input_readers)) {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                                /* Read reader_gp before write futex */
                                smp_mb_master(RCU_MB_GROUP);
                                uatomic_set(&rcu_gp.futex, 0);
                        }
                        break;
                } else {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS)
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
                                wait_gp();
                        else
                                caa_cpu_relax();
@@ -290,22 +294,21 @@ static void wait_for_readers(struct cds_list_head *input_readers,
                 * for too long.
                 */
                if (cds_list_empty(input_readers)) {
-                       if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) {
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
                                /* Read reader_gp before write futex */
                                smp_mb_master(RCU_MB_GROUP);
                                uatomic_set(&rcu_gp.futex, 0);
                        }
                        break;
                } else {
-                       switch (wait_loops) {
-                       case RCU_QS_ACTIVE_ATTEMPTS:
-                               wait_gp();
-                               break; /* only escape switch */
-                       case KICK_READER_LOOPS:
+                       if (wait_gp_loops == KICK_READER_LOOPS) {
                                smp_mb_master(RCU_MB_GROUP);
-                               wait_loops = 0;
-                               break; /* only escape switch */
-                       default:
+                               wait_gp_loops = 0;
+                       }
+                       if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) {
+                               wait_gp();
+                               wait_gp_loops++;
+                       } else {
                                caa_cpu_relax();
                        }
                }