[PATCH] bpf: add __printf() to for printf fmt strings

[Ben Dooks <ben.dooks@codethink.co.uk>]

The btf_seq_show() and btf_snprintf_show() take a printk format
string so add a __printf() to these two functions. This fixes the
following extended warnings:

kernel/bpf/btf.c:7094:29: error: function ‘btf_seq_show’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]
kernel/bpf/btf.c:7131:9: error: function ‘btf_snprintf_show’ might be a candidate for ‘gnu_printf’ format attribute [-Werror=suggest-attribute=format]

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
---
 kernel/bpf/btf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 15d71d2986d3..46c2e87c383d 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7088,8 +7088,8 @@ static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
 	btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
 }
 
-static void btf_seq_show(struct btf_show *show, const char *fmt,
-			 va_list args)
+static __printf(2,0) void btf_seq_show(struct btf_show *show, const char *fmt,
+				       va_list args)
 {
 	seq_vprintf((struct seq_file *)show->target, fmt, args);
 }
@@ -7122,7 +7122,7 @@ struct btf_show_snprintf {
 	int len;		/* length we would have written */
 };
 
-static void btf_snprintf_show(struct btf_show *show, const char *fmt,
+static __printf(2,0) void btf_snprintf_show(struct btf_show *show, const char *fmt,
 			      va_list args)
 {
 	struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
-- 
2.37.2.352.g3c44437643