X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_api.h;h=5ddb8ac460951f0bae59a3f098cf6bca510a3799;hb=f52a5702dbeb8125ca373ba363b29cbff3042cc1;hp=56dbef2aa4326c8a4067ecc96ada66b887358afd;hpb=80249235cb6560c6bb915f1cd486aa5017f87456;p=lttng-ust.git

diff --git a/libringbuffer/frontend_api.h b/libringbuffer/frontend_api.h
index 56dbef2a..5ddb8ac4 100644
--- a/libringbuffer/frontend_api.h
+++ b/libringbuffer/frontend_api.h
@@ -37,10 +37,10 @@
 /**
  * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
  *
- * Grabs RCU read-side lock and keeps a ring buffer nesting count as
- * supplementary safety net to ensure tracer client code will never
- * trigger an endless recursion. Returns the processor ID on success,
- * -EPERM on failure (nesting count too high).
+ * Keeps a ring buffer nesting count as supplementary safety net to
+ * ensure tracer client code will never trigger an endless recursion.
+ * Returns the processor ID on success, -EPERM on failure (nesting count
+ * too high).
  *
  * asm volatile and "memory" clobber prevent the compiler from moving
  * instructions out of the ring buffer nesting count. This is required to ensure
@@ -53,7 +53,6 @@ int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *confi
 {
 	int cpu, nesting;
 
-	rcu_read_lock();
 	cpu = lttng_ust_get_cpu();
 	nesting = ++URCU_TLS(lib_ring_buffer_nesting);
 	cmm_barrier();
@@ -61,7 +60,6 @@ int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *confi
 	if (caa_unlikely(nesting > 4)) {
 		WARN_ON_ONCE(1);
 		URCU_TLS(lib_ring_buffer_nesting)--;
-		rcu_read_unlock();
 		return -EPERM;
 	} else
 		return cpu;
@@ -75,7 +73,6 @@ void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *conf
 {
 	cmm_barrier();
 	URCU_TLS(lib_ring_buffer_nesting)--;		/* TLS */
-	rcu_read_unlock();
 }
 
 /*
@@ -163,14 +160,14 @@ int lib_ring_buffer_reserve(const struct lttng_ust_lib_ring_buffer_config *confi
 	unsigned long o_begin, o_end, o_old;
 	size_t before_hdr_pad = 0;
 
-	if (uatomic_read(&chan->record_disabled))
+	if (caa_unlikely(uatomic_read(&chan->record_disabled)))
 		return -EAGAIN;
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
 		buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp);
 	else
 		buf = shmp(handle, chan->backend.buf[0].shmp);
-	if (uatomic_read(&buf->record_disabled))
+	if (caa_unlikely(uatomic_read(&buf->record_disabled)))
 		return -EAGAIN;
 	ctx->buf = buf;