Bitmap definition is hard to remember and decode. Add sysctl interface
to translate human readable string like "tasks,mem,timer,lock,ftrace,..."
to bitmap.
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
---
include/linux/sys_info.h | 7 +++
lib/sys_info.c | 97 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+)
diff --git a/include/linux/sys_info.h b/include/linux/sys_info.h
index 79bf4a942e5f..0b49863cd414 100644
--- a/include/linux/sys_info.h
+++ b/include/linux/sys_info.h
@@ -16,5 +16,12 @@
#define SYS_SHOW_BLOCKED_TASKS 0x00000080
extern void sys_show_info(unsigned long info_mask);
+extern unsigned long sys_info_parse_param(char *str);
+#ifdef CONFIG_SYSCTL
+struct ctl_table;
+extern int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
+ void *buffer, size_t *lenp,
+ loff_t *ppos);
+#endif
#endif /* _LINUX_SYS_INFO_H */
diff --git a/lib/sys_info.c b/lib/sys_info.c
index 90a79b5164c9..9693542435ba 100644
--- a/lib/sys_info.c
+++ b/lib/sys_info.c
@@ -5,6 +5,103 @@
#include <linux/console.h>
#include <linux/nmi.h>
+struct sys_info_name {
+ unsigned long bit;
+ const char *name;
+};
+
+static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
+
+static const struct sys_info_name si_names[] = {
+ { SYS_SHOW_TASK_INFO, "tasks" },
+ { SYS_SHOW_MEM_INFO, "mem" },
+ { SYS_SHOW_TIMER_INFO, "timer" },
+ { SYS_SHOW_LOCK_INFO, "lock" },
+ { SYS_SHOW_FTRACE_INFO, "ftrace" },
+ { SYS_SHOW_ALL_CPU_BT, "all_bt" },
+ { SYS_SHOW_BLOCKED_TASKS, "blocked_tasks" },
+};
+
+/* Expecting string like "xxx_sys_info=tasks,mem,timer,lock,ftrace,..." */
+unsigned long sys_info_parse_param(char *str)
+{
+ unsigned long si_bits = 0;
+ char *s, *name;
+ int i;
+
+ s = str;
+ while ((name = strsep(&s, ",")) && *name) {
+ for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+ if (!strcmp(name, si_names[i].name)) {
+ si_bits |= si_names[i].bit;
+ break;
+ }
+ }
+ }
+
+ return si_bits;
+}
+
+#ifdef CONFIG_SYSCTL
+int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
+ void *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ char names[sizeof(sys_info_avail) + 1];
+ struct ctl_table table;
+ unsigned long *si_bits_global;
+ int i, ret, len;
+
+ si_bits_global = ro_table->data;
+
+ if (write) {
+ unsigned long si_bits;
+
+ table = *ro_table;
+ table.data = names;
+ table.maxlen = sizeof(names);
+ ret = proc_dostring(&table, write, buffer, lenp, ppos);
+ if (ret)
+ return ret;
+
+ si_bits = sys_info_parse_param(names);
+ /*
+ * The access to the global value is not synchronized.
+ */
+ WRITE_ONCE(*si_bits_global, si_bits);
+ return 0;
+ } else {
+ /* for 'read' operation */
+ bool first = true;
+ char *buf;
+
+ buf = names;
+ for (i = 0; i < ARRAY_SIZE(si_names); i++) {
+ if (*si_bits_global & si_names[i].bit) {
+
+ if (first) {
+ first = false;
+ } else {
+ *buf = ',';
+ buf++;
+ }
+
+ len = strlen(si_names[i].name);
+ strncpy(buf, si_names[i].name, len);
+ buf += len;
+ }
+
+ }
+ *buf = '\0';
+
+ table = *ro_table;
+ table.data = names;
+ table.maxlen = sizeof(names);
+ return proc_dostring(&table, write, buffer, lenp, ppos);
+ }
+}
+#endif
+
void sys_show_info(unsigned long info_flag)
{
if (info_flag & SYS_SHOW_TASK_INFO)
--
2.39.5 (Apple Git-154)On Mon 2025-06-16 09:08:38, Feng Tang wrote:
> Bitmap definition is hard to remember and decode. Add sysctl interface
> to translate human readable string like "tasks,mem,timer,lock,ftrace,..."
> to bitmap.
>
> Suggested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
> ---
> include/linux/sys_info.h | 7 +++
> lib/sys_info.c | 97 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 104 insertions(+)
>
> diff --git a/include/linux/sys_info.h b/include/linux/sys_info.h
> index 79bf4a942e5f..0b49863cd414 100644
> --- a/include/linux/sys_info.h
> +++ b/include/linux/sys_info.h
> @@ -16,5 +16,12 @@
> #define SYS_SHOW_BLOCKED_TASKS 0x00000080
>
> extern void sys_show_info(unsigned long info_mask);
> +extern unsigned long sys_info_parse_param(char *str);
>
> +#ifdef CONFIG_SYSCTL
> +struct ctl_table;
> +extern int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> + void *buffer, size_t *lenp,
> + loff_t *ppos);
> +#endif
> #endif /* _LINUX_SYS_INFO_H */
> diff --git a/lib/sys_info.c b/lib/sys_info.c
> index 90a79b5164c9..9693542435ba 100644
> --- a/lib/sys_info.c
> +++ b/lib/sys_info.c
> @@ -5,6 +5,103 @@
> #include <linux/console.h>
> #include <linux/nmi.h>
>
> +struct sys_info_name {
> + unsigned long bit;
> + const char *name;
> +};
> +
> +static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
> +
> +static const struct sys_info_name si_names[] = {
> + { SYS_SHOW_TASK_INFO, "tasks" },
> + { SYS_SHOW_MEM_INFO, "mem" },
> + { SYS_SHOW_TIMER_INFO, "timer" },
I see that the naming is a bit inconsistent in using singulars
vs. plurals. I suggest to use plulars when it makes sense.
It means here:
{ SYS_SHOW_TIMERS_INFO, "timers" },
> + { SYS_SHOW_LOCK_INFO, "lock" },
and here
{ SYS_SHOW_LOCKS_INFO, "locks" },
> + { SYS_SHOW_FTRACE_INFO, "ftrace" },
> + { SYS_SHOW_ALL_CPU_BT, "all_bt" },
> + { SYS_SHOW_BLOCKED_TASKS, "blocked_tasks" },
> +};
[...]
> +#ifdef CONFIG_SYSCTL
> +int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> + void *buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + char names[sizeof(sys_info_avail) + 1];
> + struct ctl_table table;
> + unsigned long *si_bits_global;
> + int i, ret, len;
> +
> + si_bits_global = ro_table->data;
> +
> + if (write) {
> + unsigned long si_bits;
> +
> + table = *ro_table;
> + table.data = names;
> + table.maxlen = sizeof(names);
> + ret = proc_dostring(&table, write, buffer, lenp, ppos);
> + if (ret)
> + return ret;
> +
> + si_bits = sys_info_parse_param(names);
> + /*
> + * The access to the global value is not synchronized.
> + */
Nit, the comment fits on a single line. I would use:
/* The access to the global value is not synchronized. */
> + WRITE_ONCE(*si_bits_global, si_bits);
> + return 0;
> + } else {
> + /* for 'read' operation */
> + bool first = true;
> + char *buf;
> +
> + buf = names;
> + for (i = 0; i < ARRAY_SIZE(si_names); i++) {
> + if (*si_bits_global & si_names[i].bit) {
> +
> + if (first) {
> + first = false;
> + } else {
> + *buf = ',';
> + buf++;
> + }
> +
> + len = strlen(si_names[i].name);
> + strncpy(buf, si_names[i].name, len);
I am afraid of a buffer overflow when people add new entry into
si_names[] table but they forget to update sys_info_avail[] string.
I would prefer to limit the write to the buffer by the size of the buffer.
Something like (on top of this patch):
--- a/lib/sys_info.c
+++ b/lib/sys_info.c
@@ -50,7 +50,7 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
char names[sizeof(sys_info_avail) + 1];
struct ctl_table table;
unsigned long *si_bits_global;
- int i, ret, len;
+ int i, ret;
si_bits_global = ro_table->data;
@@ -72,27 +72,18 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
return 0;
} else {
/* for 'read' operation */
- bool first = true;
- char *buf;
+ char *delim = "";
+ int len = 0;
- buf = names;
+ names[0] = '\0';
for (i = 0; i < ARRAY_SIZE(si_names); i++) {
if (*si_bits_global & si_names[i].bit) {
-
- if (first) {
- first = false;
- } else {
- *buf = ',';
- buf++;
- }
-
- len = strlen(si_names[i].name);
- strncpy(buf, si_names[i].name, len);
- buf += len;
+ len += scnprintf(names + len, sizeof(names) - len,
+ "%s%s", delim, si_names[i].name);
+ delim = ",";
}
}
- *buf = '\0';
table = *ro_table;
table.data = names;
Best Regards,
Petr
On Mon, Jun 23, 2025 at 04:04:56PM +0200, Petr Mladek wrote:
> On Mon 2025-06-16 09:08:38, Feng Tang wrote:
> > Bitmap definition is hard to remember and decode. Add sysctl interface
> > to translate human readable string like "tasks,mem,timer,lock,ftrace,..."
> > to bitmap.
> >
> > Suggested-by: Petr Mladek <pmladek@suse.com>
> > Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
> > ---
> > include/linux/sys_info.h | 7 +++
> > lib/sys_info.c | 97 ++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 104 insertions(+)
> >
> > diff --git a/include/linux/sys_info.h b/include/linux/sys_info.h
> > index 79bf4a942e5f..0b49863cd414 100644
> > --- a/include/linux/sys_info.h
> > +++ b/include/linux/sys_info.h
> > @@ -16,5 +16,12 @@
> > #define SYS_SHOW_BLOCKED_TASKS 0x00000080
> >
> > extern void sys_show_info(unsigned long info_mask);
> > +extern unsigned long sys_info_parse_param(char *str);
> >
> > +#ifdef CONFIG_SYSCTL
> > +struct ctl_table;
> > +extern int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> > + void *buffer, size_t *lenp,
> > + loff_t *ppos);
> > +#endif
> > #endif /* _LINUX_SYS_INFO_H */
> > diff --git a/lib/sys_info.c b/lib/sys_info.c
> > index 90a79b5164c9..9693542435ba 100644
> > --- a/lib/sys_info.c
> > +++ b/lib/sys_info.c
> > @@ -5,6 +5,103 @@
> > #include <linux/console.h>
> > #include <linux/nmi.h>
> >
> > +struct sys_info_name {
> > + unsigned long bit;
> > + const char *name;
> > +};
> > +
> > +static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
> > +
> > +static const struct sys_info_name si_names[] = {
> > + { SYS_SHOW_TASK_INFO, "tasks" },
> > + { SYS_SHOW_MEM_INFO, "mem" },
> > + { SYS_SHOW_TIMER_INFO, "timer" },
>
> I see that the naming is a bit inconsistent in using singulars
> vs. plurals. I suggest to use plulars when it makes sense.
> It means here:
>
> { SYS_SHOW_TIMERS_INFO, "timers" },
>
> > + { SYS_SHOW_LOCK_INFO, "lock" },
>
> and here
>
> { SYS_SHOW_LOCKS_INFO, "locks" },
Will change.
> > + { SYS_SHOW_FTRACE_INFO, "ftrace" },
> > + { SYS_SHOW_ALL_CPU_BT, "all_bt" },
> > + { SYS_SHOW_BLOCKED_TASKS, "blocked_tasks" },
> > +};
>
> [...]
>
> > +#ifdef CONFIG_SYSCTL
> > +int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> > + void *buffer, size_t *lenp,
> > + loff_t *ppos)
> > +{
> > + char names[sizeof(sys_info_avail) + 1];
> > + struct ctl_table table;
> > + unsigned long *si_bits_global;
> > + int i, ret, len;
> > +
> > + si_bits_global = ro_table->data;
> > +
> > + if (write) {
> > + unsigned long si_bits;
> > +
> > + table = *ro_table;
> > + table.data = names;
> > + table.maxlen = sizeof(names);
> > + ret = proc_dostring(&table, write, buffer, lenp, ppos);
> > + if (ret)
> > + return ret;
> > +
> > + si_bits = sys_info_parse_param(names);
> > + /*
> > + * The access to the global value is not synchronized.
> > + */
>
> Nit, the comment fits on a single line. I would use:
>
> /* The access to the global value is not synchronized. */
Yes.
> > + WRITE_ONCE(*si_bits_global, si_bits);
> > + return 0;
> > + } else {
> > + /* for 'read' operation */
> > + bool first = true;
> > + char *buf;
> > +
> > + buf = names;
> > + for (i = 0; i < ARRAY_SIZE(si_names); i++) {
> > + if (*si_bits_global & si_names[i].bit) {
> > +
> > + if (first) {
> > + first = false;
> > + } else {
> > + *buf = ',';
> > + buf++;
> > + }
> > +
> > + len = strlen(si_names[i].name);
> > + strncpy(buf, si_names[i].name, len);
>
> I am afraid of a buffer overflow when people add new entry into
> si_names[] table but they forget to update sys_info_avail[] string.
> I would prefer to limit the write to the buffer by the size of the buffer.
Indeed. In my v3 branch, I have also added a line to warn about it:
/*
* When 'si_names' gets updated, please make sure the 'sys_info_avail'
* below is updated accordingly.
*/
static const struct sys_info_name si_names[] = {
But still, better to do some handling in code as you suggested.
> Something like (on top of this patch):
>
> --- a/lib/sys_info.c
> +++ b/lib/sys_info.c
> @@ -50,7 +50,7 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> char names[sizeof(sys_info_avail) + 1];
> struct ctl_table table;
> unsigned long *si_bits_global;
> - int i, ret, len;
> + int i, ret;
>
> si_bits_global = ro_table->data;
>
> @@ -72,27 +72,18 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
> return 0;
> } else {
> /* for 'read' operation */
> - bool first = true;
> - char *buf;
> + char *delim = "";
> + int len = 0;
>
> - buf = names;
> + names[0] = '\0';
> for (i = 0; i < ARRAY_SIZE(si_names); i++) {
> if (*si_bits_global & si_names[i].bit) {
> -
> - if (first) {
> - first = false;
> - } else {
> - *buf = ',';
> - buf++;
> - }
> -
> - len = strlen(si_names[i].name);
> - strncpy(buf, si_names[i].name, len);
> - buf += len;
> + len += scnprintf(names + len, sizeof(names) - len,
> + "%s%s", delim, si_names[i].name);
> + delim = ",";
> }
>
> }
> - *buf = '\0';
>
> table = *ro_table;
> table.data = names;
Thanks!
- Feng
> Best Regards,
> Petr
Hi Feng,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-nonmm-unstable]
[also build test WARNING on akpm-mm/mm-everything linus/master v6.16-rc2 next-20250613]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Feng-Tang/panic-clean-up-code-for-console-replay/20250616-091042
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
patch link: https://lore.kernel.org/r/20250616010840.38258-4-feng.tang%40linux.alibaba.com
patch subject: [PATCH V2 3/5] sys_info: add help to translate sys_info string to bitmap
config: x86_64-buildonly-randconfig-001-20250616 (https://download.01.org/0day-ci/archive/20250616/202506161234.wRZSzo5v-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
rustc: rustc 1.78.0 (9b00956e5 2024-04-29)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250616/202506161234.wRZSzo5v-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/202506161234.wRZSzo5v-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> lib/sys_info.c:13:19: warning: unused variable 'sys_info_avail' [-Wunused-const-variable]
13 | static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
| ^~~~~~~~~~~~~~
1 warning generated.
vim +/sys_info_avail +13 lib/sys_info.c
12
> 13 static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
14
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On Mon, Jun 16, 2025 at 12:25:29PM +0800, kernel test robot wrote:
> Hi Feng,
>
> kernel test robot noticed the following build warnings:
>
> [auto build test WARNING on akpm-mm/mm-nonmm-unstable]
> [also build test WARNING on akpm-mm/mm-everything linus/master v6.16-rc2 next-20250613]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Feng-Tang/panic-clean-up-code-for-console-replay/20250616-091042
> base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-nonmm-unstable
> patch link: https://lore.kernel.org/r/20250616010840.38258-4-feng.tang%40linux.alibaba.com
> patch subject: [PATCH V2 3/5] sys_info: add help to translate sys_info string to bitmap
> config: x86_64-buildonly-randconfig-001-20250616 (https://download.01.org/0day-ci/archive/20250616/202506161234.wRZSzo5v-lkp@intel.com/config)
> compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
> rustc: rustc 1.78.0 (9b00956e5 2024-04-29)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250616/202506161234.wRZSzo5v-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/202506161234.wRZSzo5v-lkp@intel.com/
>
> All warnings (new ones prefixed by >>):
>
> >> lib/sys_info.c:13:19: warning: unused variable 'sys_info_avail' [-Wunused-const-variable]
> 13 | static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
> | ^~~~~~~~~~~~~~
> 1 warning generated.
Thanks for the reporting! This is related with CONFIG_SYSCTL=n, and
should be fixed by below patch:
---
diff --git a/lib/sys_info.c b/lib/sys_info.c
index 9693542435ba..ca289b4871b4 100644
--- a/lib/sys_info.c
+++ b/lib/sys_info.c
@@ -10,8 +10,6 @@ struct sys_info_name {
const char *name;
};
-static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
-
static const struct sys_info_name si_names[] = {
{ SYS_SHOW_TASK_INFO, "tasks" },
{ SYS_SHOW_MEM_INFO, "mem" },
@@ -43,6 +41,8 @@ unsigned long sys_info_parse_param(char *str)
}
#ifdef CONFIG_SYSCTL
+static const char sys_info_avail[] = "tasks,mem,timer,lock,ftrace,all_bt,blocked_tasks";
+
int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
void *buffer, size_t *lenp,
loff_t *ppos)
© 2016 - 2025 Red Hat, Inc.