libc_logging: mention that they're async signal safe.
Test: none
Change-Id: I826756d9338e80f1dd16bd650eb89892bcbbb850
diff --git a/libc/private/libc_logging.h b/libc/private/libc_logging.h
index d3e4140..f4b5968 100644
--- a/libc/private/libc_logging.h
+++ b/libc/private/libc_logging.h
@@ -76,6 +76,7 @@
//
// Formatting routines for the C library's internal debugging.
// Unlike the usual alternatives, these don't allocate, and they don't drag in all of stdio.
+// These are async signal safe, so they can be called from signal handlers.
//
int __libc_format_buffer(char* _Nonnull buf, size_t size, const char* _Nonnull fmt, ...) __printflike(3, 4);