From: Jason A. Donenfeld <Jason@zx2c4.com>
Date: Mon, 18 Mar 2019 18:49:25 +0000 (-0600)
Subject: ringlogger: document races
X-Git-Tag: 0.0.20190319-1~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=51822f722a033a481a5e0edcc51e33f5c39e9369;p=thirdparty%2Fwireguard-apple.git

ringlogger: document races

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---

diff --git a/WireGuard/Shared/Logging/ringlogger.c b/WireGuard/Shared/Logging/ringlogger.c
index 440a269..563483a 100644
--- a/WireGuard/Shared/Logging/ringlogger.c
+++ b/WireGuard/Shared/Logging/ringlogger.c
@@ -42,11 +42,14 @@ void write_msg_to_log(struct log *log, const char *tag, const char *msg)
 	struct log_line *line;
 	struct timespec ts;
 
+	// Race: This isn't synchronized with the fetch_add below, so items might be slightly out of order.
 	clock_gettime(CLOCK_REALTIME, &ts);
 
+	// Race: More than MAX_LINES writers and this will clash.
 	index = atomic_fetch_add(&log->next_index, 1);
 	line = &log->lines[index % MAX_LINES];
 
+	// Race: Before this line executes, we'll display old data after new data.
 	atomic_store(&line->time_ns, 0);
 	memset(line->line, 0, MAX_LOG_LINE_LENGTH);