sched_ext: Add __printf format attributes to scx_vexit() and bstr formatters

scx_vexit() forwards (fmt, args) to vscnprintf(); bstr_format() and
__bstr_format() forward fmt to bstr_printf(); the BPF kfunc wrappers
scx_bpf_exit_bstr(), scx_bpf_error_bstr() and scx_bpf_dump_bstr() in
turn forward fmt to those formatters. None of them have __printf(),
so clang -Wmissing-format-attribute fires on the forwarded calls and
C-side callers don't get format-string checking.

Annotate the six functions with __printf(N, 0) matching the fmt
parameter position in each.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/all/202605041112.Y6OG7v9r-lkp@intel.com/
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 966a846c213c30a90013e2b3f9138d5b8892db38..7ac7d10a41befb47f7223b9ecceb386679f3c54f 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -9338,6 +9338,7 @@ __bpf_kfunc void scx_bpf_reenqueue_local___v2(const struct bpf_prog_aux *aux)
 
 __bpf_kfunc_end_defs();
 
+__printf(5, 0)
 static s32 __bstr_format(struct scx_sched *sch, u64 *data_buf, char *line_buf,
                         size_t line_size, char *fmt, unsigned long long *data,
                         u32 data__sz)
@@ -9375,6 +9376,7 @@ static s32 __bstr_format(struct scx_sched *sch, u64 *data_buf, char *line_buf,
        return ret;
 }
 
+__printf(3, 0)
 static s32 bstr_format(struct scx_sched *sch, struct scx_bstr_buf *buf,
                       char *fmt, unsigned long long *data, u32 data__sz)
 {
@@ -9395,6 +9397,7 @@ __bpf_kfunc_start_defs();
  * Indicate that the BPF scheduler wants to exit gracefully, and initiate ops
  * disabling.
  */
+__printf(2, 0)
 __bpf_kfunc void scx_bpf_exit_bstr(s64 exit_code, char *fmt,
                                   unsigned long long *data, u32 data__sz,
                                   const struct bpf_prog_aux *aux)
@@ -9420,6 +9423,7 @@ __bpf_kfunc void scx_bpf_exit_bstr(s64 exit_code, char *fmt,
  * Indicate that the BPF scheduler encountered a fatal error and initiate ops
  * disabling.
  */
+__printf(1, 0)
 __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
                                    u32 data__sz, const struct bpf_prog_aux *aux)
 {
@@ -9447,6 +9451,7 @@ __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
  * The extra dump may be multiple lines. A single line may be split over
  * multiple calls. The last line is automatically terminated.
  */
+__printf(1, 0)
 __bpf_kfunc void scx_bpf_dump_bstr(char *fmt, unsigned long long *data,
                                   u32 data__sz, const struct bpf_prog_aux *aux)
 {

diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index b4f5dd28855e8d26bd5c133ed353d2fa0866d51d..0ed79bd891c7d0b8a6f8f67fba4d6748b69c5667 100644 (file)
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -1477,8 +1477,9 @@ int scx_kfunc_context_filter(const struct bpf_prog *prog, u32 kfunc_id);
 
 bool scx_cpu_valid(struct scx_sched *sch, s32 cpu, const char *where);
 
-bool scx_vexit(struct scx_sched *sch, enum scx_exit_kind kind, s64 exit_code,
-              s32 exit_cpu, const char *fmt, va_list args);
+__printf(5, 0) bool scx_vexit(struct scx_sched *sch, enum scx_exit_kind kind,
+                             s64 exit_code, s32 exit_cpu, const char *fmt,
+                             va_list args);
 __printf(5, 6) bool __scx_exit(struct scx_sched *sch, enum scx_exit_kind kind,
                               s64 exit_code, s32 exit_cpu, const char *fmt, ...);