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-rw-r--r--src/vppinfra/atomics.h3
-rw-r--r--src/vppinfra/lock.h12
2 files changed, 13 insertions, 2 deletions
diff --git a/src/vppinfra/atomics.h b/src/vppinfra/atomics.h
index df8e534b683..ce2177df5c2 100644
--- a/src/vppinfra/atomics.h
+++ b/src/vppinfra/atomics.h
@@ -37,11 +37,14 @@
#define clib_atomic_cmp_and_swap(addr,old,new) __sync_val_compare_and_swap(addr, old, new)
#define clib_atomic_bool_cmp_and_swap(addr,old,new) __sync_bool_compare_and_swap(addr, old, new)
+#define clib_atomic_cmp_and_swap_acq_relax_n(addr,exp,new,weak) __atomic_compare_exchange_n ((addr), (exp), (new), (weak), __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)
+
#define clib_atomic_test_and_set(a) __atomic_exchange_n(a, 1, __ATOMIC_ACQUIRE)
#define clib_atomic_release(a) __atomic_store_n(a, 0, __ATOMIC_RELEASE)
#define clib_atomic_fence_rel() __atomic_thread_fence(__ATOMIC_RELEASE);
+#define clib_atomic_load_relax_n(a) __atomic_load_n((a), __ATOMIC_RELAXED)
#define clib_atomic_load_acq_n(a) __atomic_load_n((a), __ATOMIC_ACQUIRE)
#define clib_atomic_store_rel_n(a, b) __atomic_store_n ((a), (b), __ATOMIC_RELEASE)
diff --git a/src/vppinfra/lock.h b/src/vppinfra/lock.h
index cc6a7f086b1..c1f0b87dfc6 100644
--- a/src/vppinfra/lock.h
+++ b/src/vppinfra/lock.h
@@ -17,6 +17,7 @@
#define included_clib_lock_h
#include <vppinfra/clib.h>
+#include <vppinfra/atomics.h>
#if __x86_64__
#define CLIB_PAUSE() __builtin_ia32_pause ()
@@ -76,8 +77,15 @@ clib_spinlock_free (clib_spinlock_t * p)
static_always_inline void
clib_spinlock_lock (clib_spinlock_t * p)
{
- while (clib_atomic_test_and_set (&(*p)->lock))
- CLIB_PAUSE ();
+ u32 free = 0;
+ while (!clib_atomic_cmp_and_swap_acq_relax_n (&(*p)->lock, &free, 1, 0))
+ {
+ /* atomic load limits number of compare_exchange executions */
+ while (clib_atomic_load_relax_n (&(*p)->lock))
+ CLIB_PAUSE ();
+ /* on failure, compare_exchange writes (*p)->lock into free */
+ free = 0;
+ }
CLIB_LOCK_DBG (p);
}