kernel/bpf/diagnostics.c:328:77: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 3)' attribute to the declaration of 'diag_insn_print'

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/intel-lab-lkp/linux/commits/Kumar-Kartikeya-Dwivedi/bpf-Add-verifier-diagnostics-report-helpers/20260713-235352
head:   481b092f62f3f331a53a188543b27495e7a1763c
commit: 680f28821329be1a104e6110eadde4658c51eab7 bpf: Add source and instruction diagnostic context
date:   13 hours ago
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20260714/202607140753.mH4et9Aj-lkp@intel.com/config)
compiler: clang version 22.1.8 (https://github.com/llvm/llvm-project ca7933e47d3a3451d81e72ac174dcb5aa28b59d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260714/202607140753.mH4et9Aj-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202607140753.mH4et9Aj-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/bpf/diagnostics.c:166:40: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 3)' attribute to the declaration of 'diag_log' [-Wmissing-format-attribute]
     158 | static void diag_log(struct bpf_verifier_env *env, const char *fmt, ...)
         | __attribute__((format(printf, 2, 3))) 
     159 | {
     160 |         va_list args;
     161 | 
     162 |         if (!bpf_diag_enabled(env))
     163 |                 return;
     164 | 
     165 |         va_start(args, fmt);
     166 |         bpf_verifier_vlog(&env->log, fmt, args);
         |                                               ^
   kernel/bpf/diagnostics.c:158:13: note: 'diag_log' declared here
     158 | static void diag_log(struct bpf_verifier_env *env, const char *fmt, ...)
         |             ^
   kernel/bpf/diagnostics.c:217:48: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 0)' attribute to the declaration of 'diag_vprint_indented' [-Wmissing-format-attribute]
     210 | static void diag_vprint_indented(struct bpf_verifier_env *env, const char *fmt, va_list args)
         | __attribute__((format(printf, 2, 0))) 
     211 | {
     212 |         char *buf;
     213 | 
     214 |         if (!bpf_diag_enabled(env))
     215 |                 return;
     216 | 
     217 |         buf = kvasprintf(GFP_KERNEL_ACCOUNT, fmt, args);
         |                                                       ^
   kernel/bpf/diagnostics.c:210:13: note: 'diag_vprint_indented' declared here
     210 | static void diag_vprint_indented(struct bpf_verifier_env *env, const char *fmt, va_list args)
         |             ^
>> kernel/bpf/diagnostics.c:328:77: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 3)' attribute to the declaration of 'diag_insn_print' [-Wmissing-format-attribute]
     318 | static void diag_insn_print(void *private_data, const char *fmt, ...)
         | __attribute__((format(printf, 2, 3))) 
     319 | {
     320 |         struct bpf_diag_insn_ctx *ctx = private_data;
     321 |         struct bpf_diag_insn_buf *buf = &ctx->buf;
     322 |         va_list args;
     323 | 
     324 |         if (buf->len >= buf->size)
     325 |                 return;
     326 | 
     327 |         va_start(args, fmt);
     328 |         buf->len += vscnprintf(buf->buf + buf->len, buf->size - buf->len, fmt, args);
         |                                                                                    ^
   kernel/bpf/diagnostics.c:318:13: note: 'diag_insn_print' declared here
     318 | static void diag_insn_print(void *private_data, const char *fmt, ...)
         |             ^
   kernel/bpf/diagnostics.c:446:2: error: call to undeclared function 'diag_write'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     446 |         diag_write(env, "  %s\n", source_lane);
         |         ^
   kernel/bpf/diagnostics.c:446:2: note: did you mean 'down_write'?
   include/linux/rwsem.h:241:13: note: 'down_write' declared here
     241 | extern void down_write(struct rw_semaphore *sem) __acquires(sem);
         |             ^
   kernel/bpf/diagnostics.c:455:2: error: call to undeclared function 'diag_write'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     455 |         diag_write(env, "  %s%*d | %s\n", diag_insn->idx == focus_insn_idx ? ">>> " : "    ",
         |         ^
   kernel/bpf/diagnostics.c:531:3: error: call to undeclared function 'diag_write'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     531 |                 diag_write(env, "  %*s | %*s^-- %s: %s\n", line_width + 4, "", indent, "", label,
         |                 ^
   kernel/bpf/diagnostics.c:606:2: error: call to undeclared function 'diag_write'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     606 |         diag_write(env, "  Source context:\n");
         |         ^
   3 warnings and 4 errors generated.


vim +328 kernel/bpf/diagnostics.c

   317	
   318	static void diag_insn_print(void *private_data, const char *fmt, ...)
   319	{
   320		struct bpf_diag_insn_ctx *ctx = private_data;
   321		struct bpf_diag_insn_buf *buf = &ctx->buf;
   322		va_list args;
   323	
   324		if (buf->len >= buf->size)
   325			return;
   326	
   327		va_start(args, fmt);
 > 328		buf->len += vscnprintf(buf->buf + buf->len, buf->size - buf->len, fmt, args);
   329		va_end(args);
   330	}
   331	

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