[PATCH] [v2] bpf: add printf attributes

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

Building with extra warnings enabled shows a missing printf attribute:

kernel/bpf/diagnostics.c: In function 'bpf_diag_source':
kernel/bpf/diagnostics.c:828:9: error: function 'bpf_diag_source' might be a candidate for 'gnu_printf' format attribute [-Werror=suggest-attribute=format]
  828 |         msg = bpf_diag_vfmt(env, fmt, args);

Add these to shut up the warning and allow the compiler to check the
format strings.

Fixes: b9c5d822f677 ("bpf: Add source and instruction diagnostic context")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2 changes:
 - only change the one function that needs it
 - fix line wrapping
 - use correct Fixes tag
---
 kernel/bpf/diagnostics.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/diagnostics.c b/kernel/bpf/diagnostics.c
index a2cac59c6639..48ea3ac23b63 100644
--- a/kernel/bpf/diagnostics.c
+++ b/kernel/bpf/diagnostics.c
@@ -794,8 +794,9 @@ static void diag_print_insn_context(struct bpf_verifier_env *env, u32 insn_idx,
 	}
 }
 
-static void bpf_diag_source(struct bpf_verifier_env *env, u32 insn_idx, const char *label,
-			    const char *fmt, ...)
+static __printf(4, 5) void bpf_diag_source(struct bpf_verifier_env *env,
+					   u32 insn_idx, const char *label,
+					   const char *fmt, ...)
 {
 	struct bpf_diag_scratch *scratch;
 	struct bpf_linfo_source *source_lines;
-- 
2.53.0