From: Jonathan Wiepert <jonathan.wiepert@gmail.com>
Date: Thu, 24 Apr 2025 22:14:57 +0000 (-0400)
Subject: Use thread-safe function pointer in libbpf_print
X-Git-Tag: v6.16-rc1~131^2~53
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=91dbac4076537b464639953c055c460d2bdfc7ea;p=thirdparty%2Fkernel%2Flinux.git

Use thread-safe function pointer in libbpf_print

This patch fixes a thread safety bug where libbpf_print uses the
global variable storing the print function pointer rather than the local
variable that had the print function set via __atomic_load_n.

Fixes: f1cb927cdb62 ("libbpf: Ensure print callback usage is thread-safe")
Signed-off-by: Jonathan Wiepert <jonathan.wiepert@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>
Link: https://lore.kernel.org/bpf/20250424221457.793068-1-jonathan.wiepert@gmail.com
---

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 080c699582c79..617cfb9a7ff50 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -286,7 +286,7 @@ void libbpf_print(enum libbpf_print_level level, const char *format, ...)
 	old_errno = errno;
 
 	va_start(args, format);
-	__libbpf_pr(level, format, args);
+	print_fn(level, format, args);
 	va_end(args);
 
 	errno = old_errno;