#include "frontend.h"
/**
- * lib_ring_buffer_get_cpu - Precedes ring buffer reserve/commit.
+ * lib_ring_buffer_nesting_inc - Ring buffer recursive use protection.
*
- * 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).
+ * The rint buffer buffer nesting count is a safety net to ensure tracer
+ * client code will never trigger an endless recursion.
+ * Returns 0 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
* section.
*/
static inline
-int lib_ring_buffer_get_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
+int lib_ring_buffer_nesting_inc(const struct lttng_ust_lib_ring_buffer_config *config)
{
- int cpu, nesting;
+ int nesting;
- cpu = lttng_ust_get_cpu();
nesting = ++URCU_TLS(lib_ring_buffer_nesting);
cmm_barrier();
-
if (caa_unlikely(nesting > 4)) {
WARN_ON_ONCE(1);
URCU_TLS(lib_ring_buffer_nesting)--;
return -EPERM;
- } else
- return cpu;
+ }
+ return 0;
}
-/**
- * lib_ring_buffer_put_cpu - Follows ring buffer reserve/commit.
- */
static inline
-void lib_ring_buffer_put_cpu(const struct lttng_ust_lib_ring_buffer_config *config)
+void lib_ring_buffer_nesting_dec(const struct lttng_ust_lib_ring_buffer_config *config)
{
cmm_barrier();
URCU_TLS(lib_ring_buffer_nesting)--; /* TLS */
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
+ if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+ ctx->reserve_cpu = lttng_ust_get_cpu();
+ buf = shmp(handle, chan->backend.buf[ctx->reserve_cpu].shmp);
+ } else {
buf = shmp(handle, chan->backend.buf[0].shmp);
+ }
if (caa_unlikely(!buf))
return -EIO;
if (caa_unlikely(uatomic_read(&buf->record_disabled)))