[PATCH] tracing: remove __printf() attribute on __ftrace_vbprintk()

[Arnd Bergmann <arnd@kernel.org>]

From: Arnd Bergmann <arnd@arndb.de>

The sunrpc change to use trace_printk() for debugging caused
a new warning for every instance of dprintk() in some configurations,
when -Wformat-security is enabled:

fs/nfs/getroot.c: In function 'nfs_get_root':
fs/nfs/getroot.c:90:17: error: format not a string literal and no format arguments [-Werror=format-security]
   90 |                 nfs_errorf(fc, "NFS: Couldn't getattr on root");

I've been slowly chipping away at those warnings over time with the
intention of enabling them by default in the future. While I could not
figure out why this only happens for this one instance, I see that the
__trace_bprintk() function is always called with a local variable as
the format string, rather than a literal.

Remove the __printf(2,3) annotation on this function, as this is can
only be validated for literals. The format strings still get checked
because the underlying literal keeps getting passed into __trace_printk()
in the "else" branch, which is not taken but still evaluated for
compile-time warnings.

Fixes: ec7d8e68ef0e ("sunrpc: add a Kconfig option to redirect dfprintk() output to trace buffer")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/trace_printk.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/trace_printk.h b/include/linux/trace_printk.h
index bb5874097f24..2670ec7f4262 100644
--- a/include/linux/trace_printk.h
+++ b/include/linux/trace_printk.h
@@ -107,7 +107,6 @@ do {									\
 		__trace_printk(_THIS_IP_, fmt, ##args);			\
 } while (0)
 
-extern __printf(2, 3)
 int __trace_bprintk(unsigned long ip, const char *fmt, ...);
 
 extern __printf(2, 3)
-- 
2.39.5