X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libringbuffer%2Ffrontend_internal.h;h=1fb08dfdec90d3f25e5f7ce85f39c010386badf4;hb=49deb55988d873a8b8084ca75644b7d61c7a047c;hp=02cb4d4a75d37c4b70f1f515be7fe5a1e18443d9;hpb=950aab0c40f2e2c66aabe94a8b8a1b554b2b2c27;p=lttng-ust.git

diff --git a/libringbuffer/frontend_internal.h b/libringbuffer/frontend_internal.h
index 02cb4d4a..1fb08dfd 100644
--- a/libringbuffer/frontend_internal.h
+++ b/libringbuffer/frontend_internal.h
@@ -386,6 +386,20 @@ void lib_ring_buffer_check_deliver(const struct lib_ring_buffer_config *config,
 					 * Wake-up the other end by
 					 * writing a null byte in the
 					 * pipe (non-blocking).
+					 * Important note: Because
+					 * writing into the pipe is
+					 * non-blocking (and therefore
+					 * we allow dropping wakeup
+					 * data, as long as there is
+					 * wakeup data present in the
+					 * pipe buffer to wake up the
+					 * consumer), the consumer
+					 * should perform the following
+					 * sequence for waiting:
+					 * 1) empty the pipe (reads).
+					 * 2) check if there is data in
+					 *    the buffer.
+					 * 3) wait on the pipe (poll).
 					 */
 					do {
 						ret = write(wakeup_fd, "", 1);