linuxrwlocks: two bug fixes; guess the model checker helps find bugs

diff --git a/test/linuxrwlocks.c b/test/linuxrwlocks.c
index a616b67c1b55162ee73a5096aa4317a42d2ecc48..dcf323caed1383d0c973a2801b52e00517b0d21b 100644 (file)
--- a/test/linuxrwlocks.c
+++ b/test/linuxrwlocks.c
@@ -28,32 +28,32 @@ static inline int write_can_lock(rwlock_t *lock)
 
 static inline void read_lock(rwlock_t *rw)
 {
-       int currentvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
-       while (currentvalue<0) {
+       int priorvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
+       while (priorvalue<=0) {
                atomic_fetch_add_explicit(&rw->lock, 1, memory_order_relaxed);
                do {
-                       currentvalue=atomic_load_explicit(&rw->lock, memory_order_relaxed);
-               }       while(currentvalue<=0);
-               currentvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
+                       priorvalue=atomic_load_explicit(&rw->lock, memory_order_relaxed);
+               }       while(priorvalue<=0);
+               priorvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
        }
 }
 
 static inline void write_lock(rwlock_t *rw)
 {
-       int currentvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
-       while (currentvalue!=0) {
+       int priorvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
+       while (priorvalue!=RW_LOCK_BIAS) {
                atomic_fetch_add_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_relaxed);
                do {
-                       currentvalue=atomic_load_explicit(&rw->lock, memory_order_relaxed);
-               }       while(currentvalue!=RW_LOCK_BIAS);
-               currentvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
+                       priorvalue=atomic_load_explicit(&rw->lock, memory_order_relaxed);
+               }       while(priorvalue!=RW_LOCK_BIAS);
+               priorvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
        }
 }
 
 static inline int read_trylock(rwlock_t *rw)
 {
-       int currentvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
-       if (currentvalue>=0)
+       int priorvalue=atomic_fetch_sub_explicit(&rw->lock, 1, memory_order_acquire);
+       if (priorvalue>0)
                return 1;
        
        atomic_fetch_add_explicit(&rw->lock, 1, memory_order_relaxed);
@@ -62,8 +62,8 @@ static inline int read_trylock(rwlock_t *rw)
 
 static inline int write_trylock(rwlock_t *rw)
 {
-       int currentvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
-       if (currentvalue>=0)
+       int priorvalue=atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_acquire);
+       if (priorvalue==RW_LOCK_BIAS)
                return 1;
        
        atomic_fetch_add_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_relaxed);