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Message-ID: <202512090407.VxRO6xAS-lkp@intel.com>
Date: Tue, 9 Dec 2025 04:04:34 +0800
From: kernel test robot <lkp@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>,
Kees Cook <kees@...nel.org>
Subject: kernel/sched/ext.c:6942:27: warning: diagnostic behavior may be
improved by adding the 'format(printf, 4, 0)' attribute to the declaration
of '__bstr_format'
Hi Andy,
First bad commit (maybe != root cause):
tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: c2f2b01b74be8b40a2173372bcd770723f87e7b2
commit: 7bf819aa992faee980610e9021aec0c38aac53be vsnprintf: Mark binary printing functions with __printf() attribute
date: 9 months ago
config: sparc64-randconfig-001-20251209 (https://download.01.org/0day-ci/archive/20251209/202512090407.VxRO6xAS-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 6ec8c4351cfc1d0627d1633b02ea787bd29c77d8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251209/202512090407.VxRO6xAS-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512090407.VxRO6xAS-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from kernel/sched/build_policy.c:63:
kernel/sched/ext.c:1809:9: warning: default initialization of an object of type 'typeof (b->scx.dsq_vtime)' (aka 'const unsigned long long') leaves the object uninitialized [-Wdefault-const-init-var-unsafe]
1809 | return time_before64(a->scx.dsq_vtime, b->scx.dsq_vtime);
| ^
include/linux/jiffies.h:212:28: note: expanded from macro 'time_before64'
212 | #define time_before64(a,b) time_after64(b,a)
| ^
include/linux/jiffies.h:199:3: note: expanded from macro 'time_after64'
199 | (typecheck(__u64, a) && \
| ^
include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck'
11 | typeof(x) __dummy2; \
| ^
In file included from kernel/sched/build_policy.c:63:
kernel/sched/ext.c:1809:9: warning: default initialization of an object of type 'typeof (a->scx.dsq_vtime)' (aka 'const unsigned long long') leaves the object uninitialized [-Wdefault-const-init-var-unsafe]
include/linux/jiffies.h:212:28: note: expanded from macro 'time_before64'
212 | #define time_before64(a,b) time_after64(b,a)
| ^
include/linux/jiffies.h:200:3: note: expanded from macro 'time_after64'
200 | typecheck(__u64, b) && \
| ^
include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck'
11 | typeof(x) __dummy2; \
| ^
In file included from kernel/sched/build_policy.c:63:
>> kernel/sched/ext.c:6942:27: warning: diagnostic behavior may be improved by adding the 'format(printf, 4, 0)' attribute to the declaration of '__bstr_format' [-Wmissing-format-attribute]
6915 | bprintf_data.bin_args);
| ^
kernel/sched/ext.c:6915:12: note: '__bstr_format' declared here
6915 | static s32 __bstr_format(u64 *data_buf, char *line_buf, size_t line_size,
| ^
>> kernel/sched/ext.c:6957:28: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 0)' attribute to the declaration of 'bstr_format' [-Wmissing-format-attribute]
6953 | static s32 bstr_format(struct scx_bstr_buf *buf,
| __attribute__((format(printf, 2, 0)))
6954 | char *fmt, unsigned long long *data, u32 data__sz)
6955 | {
6956 | return __bstr_format(buf->data, buf->line, sizeof(buf->line),
6957 | fmt, data, data__sz);
| ^
kernel/sched/ext.c:6953:12: note: 'bstr_format' declared here
6953 | static s32 bstr_format(struct scx_bstr_buf *buf,
| ^
>> kernel/sched/ext.c:6978:57: warning: diagnostic behavior may be improved by adding the 'format(printf, 2, 0)' attribute to the declaration of 'scx_bpf_exit_bstr' [-Wmissing-format-attribute]
6972 | __bpf_kfunc void scx_bpf_exit_bstr(s64 exit_code, char *fmt,
| __attribute__((format(printf, 2, 0)))
6973 | unsigned long long *data, u32 data__sz)
6974 | {
6975 | unsigned long flags;
6976 |
6977 | raw_spin_lock_irqsave(&scx_exit_bstr_buf_lock, flags);
6978 | if (bstr_format(&scx_exit_bstr_buf, fmt, data, data__sz) >= 0)
| ^
kernel/sched/ext.c:6972:18: note: 'scx_bpf_exit_bstr' declared here
6972 | __bpf_kfunc void scx_bpf_exit_bstr(s64 exit_code, char *fmt,
| ^
>> kernel/sched/ext.c:6999:57: warning: diagnostic behavior may be improved by adding the 'format(printf, 1, 0)' attribute to the declaration of 'scx_bpf_error_bstr' [-Wmissing-format-attribute]
6993 | __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
| __attribute__((format(printf, 1, 0)))
6994 | u32 data__sz)
6995 | {
6996 | unsigned long flags;
6997 |
6998 | raw_spin_lock_irqsave(&scx_exit_bstr_buf_lock, flags);
6999 | if (bstr_format(&scx_exit_bstr_buf, fmt, data, data__sz) >= 0)
| ^
kernel/sched/ext.c:6993:18: note: 'scx_bpf_error_bstr' declared here
6993 | __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
| ^
>> kernel/sched/ext.c:7031:59: warning: diagnostic behavior may be improved by adding the 'format(printf, 1, 0)' attribute to the declaration of 'scx_bpf_dump_bstr' [-Wmissing-format-attribute]
7017 | __bpf_kfunc void scx_bpf_dump_bstr(char *fmt, unsigned long long *data,
| __attribute__((format(printf, 1, 0)))
7018 | u32 data__sz)
7019 | {
7020 | struct scx_dump_data *dd = &scx_dump_data;
7021 | struct scx_bstr_buf *buf = &dd->buf;
7022 | s32 ret;
7023 |
7024 | if (raw_smp_processor_id() != dd->cpu) {
7025 | scx_ops_error("scx_bpf_dump() must only be called from ops.dump() and friends");
7026 | return;
7027 | }
7028 |
7029 | /* append the formatted string to the line buf */
7030 | ret = __bstr_format(buf->data, buf->line + dd->cursor,
7031 | sizeof(buf->line) - dd->cursor, fmt, data, data__sz);
| ^
kernel/sched/ext.c:7017:18: note: 'scx_bpf_dump_bstr' declared here
7017 | __bpf_kfunc void scx_bpf_dump_bstr(char *fmt, unsigned long long *data,
| ^
7 warnings generated.
vim +6942 kernel/sched/ext.c
f0e1a0643a59bf Tejun Heo 2024-06-18 6914
f0e1a0643a59bf Tejun Heo 2024-06-18 6915 static s32 __bstr_format(u64 *data_buf, char *line_buf, size_t line_size,
f0e1a0643a59bf Tejun Heo 2024-06-18 6916 char *fmt, unsigned long long *data, u32 data__sz)
f0e1a0643a59bf Tejun Heo 2024-06-18 6917 {
f0e1a0643a59bf Tejun Heo 2024-06-18 6918 struct bpf_bprintf_data bprintf_data = { .get_bin_args = true };
f0e1a0643a59bf Tejun Heo 2024-06-18 6919 s32 ret;
f0e1a0643a59bf Tejun Heo 2024-06-18 6920
f0e1a0643a59bf Tejun Heo 2024-06-18 6921 if (data__sz % 8 || data__sz > MAX_BPRINTF_VARARGS * 8 ||
f0e1a0643a59bf Tejun Heo 2024-06-18 6922 (data__sz && !data)) {
f0e1a0643a59bf Tejun Heo 2024-06-18 6923 scx_ops_error("invalid data=%p and data__sz=%u",
f0e1a0643a59bf Tejun Heo 2024-06-18 6924 (void *)data, data__sz);
f0e1a0643a59bf Tejun Heo 2024-06-18 6925 return -EINVAL;
f0e1a0643a59bf Tejun Heo 2024-06-18 6926 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6927
f0e1a0643a59bf Tejun Heo 2024-06-18 6928 ret = copy_from_kernel_nofault(data_buf, data, data__sz);
f0e1a0643a59bf Tejun Heo 2024-06-18 6929 if (ret < 0) {
f0e1a0643a59bf Tejun Heo 2024-06-18 6930 scx_ops_error("failed to read data fields (%d)", ret);
f0e1a0643a59bf Tejun Heo 2024-06-18 6931 return ret;
f0e1a0643a59bf Tejun Heo 2024-06-18 6932 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6933
f0e1a0643a59bf Tejun Heo 2024-06-18 6934 ret = bpf_bprintf_prepare(fmt, UINT_MAX, data_buf, data__sz / 8,
f0e1a0643a59bf Tejun Heo 2024-06-18 6935 &bprintf_data);
f0e1a0643a59bf Tejun Heo 2024-06-18 6936 if (ret < 0) {
f0e1a0643a59bf Tejun Heo 2024-06-18 6937 scx_ops_error("format preparation failed (%d)", ret);
f0e1a0643a59bf Tejun Heo 2024-06-18 6938 return ret;
f0e1a0643a59bf Tejun Heo 2024-06-18 6939 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6940
f0e1a0643a59bf Tejun Heo 2024-06-18 6941 ret = bstr_printf(line_buf, line_size, fmt,
f0e1a0643a59bf Tejun Heo 2024-06-18 @6942 bprintf_data.bin_args);
f0e1a0643a59bf Tejun Heo 2024-06-18 6943 bpf_bprintf_cleanup(&bprintf_data);
f0e1a0643a59bf Tejun Heo 2024-06-18 6944 if (ret < 0) {
f0e1a0643a59bf Tejun Heo 2024-06-18 6945 scx_ops_error("(\"%s\", %p, %u) failed to format",
f0e1a0643a59bf Tejun Heo 2024-06-18 6946 fmt, data, data__sz);
f0e1a0643a59bf Tejun Heo 2024-06-18 6947 return ret;
f0e1a0643a59bf Tejun Heo 2024-06-18 6948 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6949
f0e1a0643a59bf Tejun Heo 2024-06-18 6950 return ret;
f0e1a0643a59bf Tejun Heo 2024-06-18 6951 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6952
f0e1a0643a59bf Tejun Heo 2024-06-18 @6953 static s32 bstr_format(struct scx_bstr_buf *buf,
f0e1a0643a59bf Tejun Heo 2024-06-18 6954 char *fmt, unsigned long long *data, u32 data__sz)
f0e1a0643a59bf Tejun Heo 2024-06-18 6955 {
f0e1a0643a59bf Tejun Heo 2024-06-18 6956 return __bstr_format(buf->data, buf->line, sizeof(buf->line),
f0e1a0643a59bf Tejun Heo 2024-06-18 @6957 fmt, data, data__sz);
f0e1a0643a59bf Tejun Heo 2024-06-18 6958 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6959
f0e1a0643a59bf Tejun Heo 2024-06-18 6960 __bpf_kfunc_start_defs();
f0e1a0643a59bf Tejun Heo 2024-06-18 6961
f0e1a0643a59bf Tejun Heo 2024-06-18 6962 /**
f0e1a0643a59bf Tejun Heo 2024-06-18 6963 * scx_bpf_exit_bstr - Gracefully exit the BPF scheduler.
f0e1a0643a59bf Tejun Heo 2024-06-18 6964 * @exit_code: Exit value to pass to user space via struct scx_exit_info.
f0e1a0643a59bf Tejun Heo 2024-06-18 6965 * @fmt: error message format string
f0e1a0643a59bf Tejun Heo 2024-06-18 6966 * @data: format string parameters packaged using ___bpf_fill() macro
f0e1a0643a59bf Tejun Heo 2024-06-18 6967 * @data__sz: @data len, must end in '__sz' for the verifier
f0e1a0643a59bf Tejun Heo 2024-06-18 6968 *
f0e1a0643a59bf Tejun Heo 2024-06-18 6969 * Indicate that the BPF scheduler wants to exit gracefully, and initiate ops
f0e1a0643a59bf Tejun Heo 2024-06-18 6970 * disabling.
f0e1a0643a59bf Tejun Heo 2024-06-18 6971 */
f0e1a0643a59bf Tejun Heo 2024-06-18 @6972 __bpf_kfunc void scx_bpf_exit_bstr(s64 exit_code, char *fmt,
f0e1a0643a59bf Tejun Heo 2024-06-18 6973 unsigned long long *data, u32 data__sz)
f0e1a0643a59bf Tejun Heo 2024-06-18 6974 {
f0e1a0643a59bf Tejun Heo 2024-06-18 6975 unsigned long flags;
f0e1a0643a59bf Tejun Heo 2024-06-18 6976
f0e1a0643a59bf Tejun Heo 2024-06-18 6977 raw_spin_lock_irqsave(&scx_exit_bstr_buf_lock, flags);
f0e1a0643a59bf Tejun Heo 2024-06-18 @6978 if (bstr_format(&scx_exit_bstr_buf, fmt, data, data__sz) >= 0)
f0e1a0643a59bf Tejun Heo 2024-06-18 6979 scx_ops_exit_kind(SCX_EXIT_UNREG_BPF, exit_code, "%s",
f0e1a0643a59bf Tejun Heo 2024-06-18 6980 scx_exit_bstr_buf.line);
f0e1a0643a59bf Tejun Heo 2024-06-18 6981 raw_spin_unlock_irqrestore(&scx_exit_bstr_buf_lock, flags);
f0e1a0643a59bf Tejun Heo 2024-06-18 6982 }
f0e1a0643a59bf Tejun Heo 2024-06-18 6983
f0e1a0643a59bf Tejun Heo 2024-06-18 6984 /**
f0e1a0643a59bf Tejun Heo 2024-06-18 6985 * scx_bpf_error_bstr - Indicate fatal error
f0e1a0643a59bf Tejun Heo 2024-06-18 6986 * @fmt: error message format string
f0e1a0643a59bf Tejun Heo 2024-06-18 6987 * @data: format string parameters packaged using ___bpf_fill() macro
f0e1a0643a59bf Tejun Heo 2024-06-18 6988 * @data__sz: @data len, must end in '__sz' for the verifier
f0e1a0643a59bf Tejun Heo 2024-06-18 6989 *
f0e1a0643a59bf Tejun Heo 2024-06-18 6990 * Indicate that the BPF scheduler encountered a fatal error and initiate ops
f0e1a0643a59bf Tejun Heo 2024-06-18 6991 * disabling.
f0e1a0643a59bf Tejun Heo 2024-06-18 6992 */
f0e1a0643a59bf Tejun Heo 2024-06-18 @6993 __bpf_kfunc void scx_bpf_error_bstr(char *fmt, unsigned long long *data,
f0e1a0643a59bf Tejun Heo 2024-06-18 6994 u32 data__sz)
f0e1a0643a59bf Tejun Heo 2024-06-18 6995 {
f0e1a0643a59bf Tejun Heo 2024-06-18 6996 unsigned long flags;
f0e1a0643a59bf Tejun Heo 2024-06-18 6997
f0e1a0643a59bf Tejun Heo 2024-06-18 6998 raw_spin_lock_irqsave(&scx_exit_bstr_buf_lock, flags);
f0e1a0643a59bf Tejun Heo 2024-06-18 @6999 if (bstr_format(&scx_exit_bstr_buf, fmt, data, data__sz) >= 0)
f0e1a0643a59bf Tejun Heo 2024-06-18 7000 scx_ops_exit_kind(SCX_EXIT_ERROR_BPF, 0, "%s",
f0e1a0643a59bf Tejun Heo 2024-06-18 7001 scx_exit_bstr_buf.line);
f0e1a0643a59bf Tejun Heo 2024-06-18 7002 raw_spin_unlock_irqrestore(&scx_exit_bstr_buf_lock, flags);
f0e1a0643a59bf Tejun Heo 2024-06-18 7003 }
f0e1a0643a59bf Tejun Heo 2024-06-18 7004
07814a9439a3b0 Tejun Heo 2024-06-18 7005 /**
987ce79b5242c0 Randy Dunlap 2025-01-10 7006 * scx_bpf_dump_bstr - Generate extra debug dump specific to the BPF scheduler
07814a9439a3b0 Tejun Heo 2024-06-18 7007 * @fmt: format string
07814a9439a3b0 Tejun Heo 2024-06-18 7008 * @data: format string parameters packaged using ___bpf_fill() macro
07814a9439a3b0 Tejun Heo 2024-06-18 7009 * @data__sz: @data len, must end in '__sz' for the verifier
07814a9439a3b0 Tejun Heo 2024-06-18 7010 *
07814a9439a3b0 Tejun Heo 2024-06-18 7011 * To be called through scx_bpf_dump() helper from ops.dump(), dump_cpu() and
07814a9439a3b0 Tejun Heo 2024-06-18 7012 * dump_task() to generate extra debug dump specific to the BPF scheduler.
07814a9439a3b0 Tejun Heo 2024-06-18 7013 *
07814a9439a3b0 Tejun Heo 2024-06-18 7014 * The extra dump may be multiple lines. A single line may be split over
07814a9439a3b0 Tejun Heo 2024-06-18 7015 * multiple calls. The last line is automatically terminated.
07814a9439a3b0 Tejun Heo 2024-06-18 7016 */
07814a9439a3b0 Tejun Heo 2024-06-18 7017 __bpf_kfunc void scx_bpf_dump_bstr(char *fmt, unsigned long long *data,
07814a9439a3b0 Tejun Heo 2024-06-18 7018 u32 data__sz)
07814a9439a3b0 Tejun Heo 2024-06-18 7019 {
07814a9439a3b0 Tejun Heo 2024-06-18 7020 struct scx_dump_data *dd = &scx_dump_data;
07814a9439a3b0 Tejun Heo 2024-06-18 7021 struct scx_bstr_buf *buf = &dd->buf;
07814a9439a3b0 Tejun Heo 2024-06-18 7022 s32 ret;
07814a9439a3b0 Tejun Heo 2024-06-18 7023
07814a9439a3b0 Tejun Heo 2024-06-18 7024 if (raw_smp_processor_id() != dd->cpu) {
07814a9439a3b0 Tejun Heo 2024-06-18 7025 scx_ops_error("scx_bpf_dump() must only be called from ops.dump() and friends");
07814a9439a3b0 Tejun Heo 2024-06-18 7026 return;
07814a9439a3b0 Tejun Heo 2024-06-18 7027 }
07814a9439a3b0 Tejun Heo 2024-06-18 7028
07814a9439a3b0 Tejun Heo 2024-06-18 7029 /* append the formatted string to the line buf */
07814a9439a3b0 Tejun Heo 2024-06-18 7030 ret = __bstr_format(buf->data, buf->line + dd->cursor,
07814a9439a3b0 Tejun Heo 2024-06-18 @7031 sizeof(buf->line) - dd->cursor, fmt, data, data__sz);
07814a9439a3b0 Tejun Heo 2024-06-18 7032 if (ret < 0) {
07814a9439a3b0 Tejun Heo 2024-06-18 7033 dump_line(dd->s, "%s[!] (\"%s\", %p, %u) failed to format (%d)",
07814a9439a3b0 Tejun Heo 2024-06-18 7034 dd->prefix, fmt, data, data__sz, ret);
07814a9439a3b0 Tejun Heo 2024-06-18 7035 return;
07814a9439a3b0 Tejun Heo 2024-06-18 7036 }
07814a9439a3b0 Tejun Heo 2024-06-18 7037
07814a9439a3b0 Tejun Heo 2024-06-18 7038 dd->cursor += ret;
07814a9439a3b0 Tejun Heo 2024-06-18 7039 dd->cursor = min_t(s32, dd->cursor, sizeof(buf->line));
07814a9439a3b0 Tejun Heo 2024-06-18 7040
07814a9439a3b0 Tejun Heo 2024-06-18 7041 if (!dd->cursor)
07814a9439a3b0 Tejun Heo 2024-06-18 7042 return;
07814a9439a3b0 Tejun Heo 2024-06-18 7043
07814a9439a3b0 Tejun Heo 2024-06-18 7044 /*
07814a9439a3b0 Tejun Heo 2024-06-18 7045 * If the line buf overflowed or ends in a newline, flush it into the
07814a9439a3b0 Tejun Heo 2024-06-18 7046 * dump. This is to allow the caller to generate a single line over
07814a9439a3b0 Tejun Heo 2024-06-18 7047 * multiple calls. As ops_dump_flush() can also handle multiple lines in
07814a9439a3b0 Tejun Heo 2024-06-18 7048 * the line buf, the only case which can lead to an unexpected
07814a9439a3b0 Tejun Heo 2024-06-18 7049 * truncation is when the caller keeps generating newlines in the middle
07814a9439a3b0 Tejun Heo 2024-06-18 7050 * instead of the end consecutively. Don't do that.
07814a9439a3b0 Tejun Heo 2024-06-18 7051 */
07814a9439a3b0 Tejun Heo 2024-06-18 7052 if (dd->cursor >= sizeof(buf->line) || buf->line[dd->cursor - 1] == '\n')
07814a9439a3b0 Tejun Heo 2024-06-18 7053 ops_dump_flush();
07814a9439a3b0 Tejun Heo 2024-06-18 7054 }
07814a9439a3b0 Tejun Heo 2024-06-18 7055
:::::: The code at line 6942 was first introduced by commit
:::::: f0e1a0643a59bf1f922fa209cec86a170b784f3f sched_ext: Implement BPF extensible scheduler class
:::::: TO: Tejun Heo <tj@...nel.org>
:::::: CC: Tejun Heo <tj@...nel.org>
--
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