Introduce two new sysctl interfaces for configuring global loglevels:
- kernel.console_loglevel: Sets the global console loglevel, determining
the minimum priority of messages printed to consoles. Messages with a
loglevel lower than this value will be printed.
- kernel.default_message_loglevel: Sets the default loglevel for
messages that do not specify an explicit loglevel.
The kernel.printk sysctl was previously used to set multiple loglevel
parameters simultaneously, but it was confusing and lacked proper
validation. By introducing these dedicated sysctl interfaces, we provide
a clearer and more granular way to configure the loglevels.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Chris Down <chris@chrisdown.name>
---
Documentation/admin-guide/sysctl/kernel.rst | 17 +++++-
include/linux/sysctl.h | 7 +++
kernel/printk/sysctl.c | 63 +++++++++++++++++++++
kernel/sysctl.c | 18 +++---
4 files changed, 95 insertions(+), 10 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index f3ee807b5d8b..043d5f663b7d 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -1079,6 +1079,20 @@ otherwise the 'doze' mode will be used.
==============================================================
+Some of these settings may be overridden per-console, see
+Documentation/admin-guide/per-console-loglevel.rst. See ``man 2 syslog`` for
+more information on the different loglevels.
+
+console_loglevel
+================
+
+Messages with a higher priority than this will be printed to consoles.
+
+default_message_loglevel
+========================
+
+Messages without an explicit priority will be printed with this priority.
+
printk
======
@@ -1087,8 +1101,7 @@ The four values in printk denote: ``console_loglevel``,
``default_console_loglevel`` respectively.
These values influence printk() behavior when printing or
-logging error messages. See '``man 2 syslog``' for more info on
-the different loglevels.
+logging error messages.
======================== =====================================
console_loglevel messages with a higher priority than
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 92e9146b1104..c2f72d172f64 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -235,6 +235,13 @@ extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
void do_sysctl_args(void);
bool sysctl_is_alias(char *param);
+int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int *valp,
+ int write, void *data);
+int do_proc_dointvec(const struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos,
+ int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
+ int write, void *data),
+ void *data);
int do_proc_douintvec(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp,
diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
index da77f3f5c1fe..034739939a61 100644
--- a/kernel/printk/sysctl.c
+++ b/kernel/printk/sysctl.c
@@ -11,6 +11,9 @@
static const int ten_thousand = 10000;
+static int min_msg_loglevel = LOGLEVEL_EMERG;
+static int max_msg_loglevel = LOGLEVEL_DEBUG;
+
static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
@@ -20,6 +23,50 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
}
+static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
+ int *valp,
+ int write, void *data)
+{
+ int level, ret;
+
+ /*
+ * If writing, first do so via a temporary local int so we can
+ * bounds-check it before touching *valp.
+ */
+ int *intp = write ? &level : valp;
+
+ ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
+ if (ret)
+ return ret;
+
+ if (write) {
+ if (level != console_clamp_loglevel(level))
+ return -ERANGE;
+
+ /*
+ * Honour the administrator-configured minimum console
+ * loglevel (third element of kernel.printk). This mirrors
+ * the syslog() and sysfs control paths so that once the floor
+ * is raised we do not let this sysctl silently bypass it.
+ */
+ if (minimum_console_loglevel > CONSOLE_LOGLEVEL_MIN &&
+ level < minimum_console_loglevel)
+ level = minimum_console_loglevel;
+
+ WRITE_ONCE(*valp, level);
+ }
+
+ return 0;
+}
+
+static int proc_dointvec_console_loglevel(const struct ctl_table *table,
+ int write, void *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ return do_proc_dointvec(table, write, buffer, lenp, ppos,
+ do_proc_dointvec_console_loglevel, NULL);
+}
+
static const struct ctl_table printk_sysctls[] = {
{
.procname = "printk",
@@ -76,6 +123,22 @@ static const struct ctl_table printk_sysctls[] = {
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_TWO,
},
+ {
+ .procname = "console_loglevel",
+ .data = &console_loglevel,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_console_loglevel,
+ },
+ {
+ .procname = "default_message_loglevel",
+ .data = &default_message_loglevel,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &min_msg_loglevel,
+ .extra2 = &max_msg_loglevel,
+ },
};
void __init printk_sysctl_init(void)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index cb6196e3fa99..3ed010b8f6b3 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -354,9 +354,9 @@ static void proc_put_char(void **buf, size_t *size, char c)
}
}
-static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
- int *valp,
- int write, void *data)
+int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
+ int *valp,
+ int write, void *data)
{
if (write) {
if (*negp) {
@@ -380,6 +380,7 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
}
return 0;
}
+EXPORT_SYMBOL(do_proc_dointvec_conv);
static int do_proc_douintvec_conv(unsigned long *lvalp,
unsigned int *valp,
@@ -471,15 +472,16 @@ static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table,
return err;
}
-static int do_proc_dointvec(const struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos,
- int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
- int write, void *data),
- void *data)
+int do_proc_dointvec(const struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos,
+ int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
+ int write, void *data),
+ void *data)
{
return __do_proc_dointvec(table->data, table, write,
buffer, lenp, ppos, conv, data);
}
+EXPORT_SYMBOL(do_proc_dointvec);
static int do_proc_douintvec_w(unsigned int *tbl_data,
const struct ctl_table *table,
--
2.51.2Adding Joel into Cc. Joel, see the original patch at
https://lore.kernel.org/all/c3e5cc507eb3fd7db0a002f31d7e47d764cad176.1764272407.git.chris@chrisdown.name/
On Fri 2025-11-28 03:44:25, Chris Down wrote:
> Introduce two new sysctl interfaces for configuring global loglevels:
>
> - kernel.console_loglevel: Sets the global console loglevel, determining
> the minimum priority of messages printed to consoles. Messages with a
> loglevel lower than this value will be printed.
> - kernel.default_message_loglevel: Sets the default loglevel for
> messages that do not specify an explicit loglevel.
>
> The kernel.printk sysctl was previously used to set multiple loglevel
> parameters simultaneously, but it was confusing and lacked proper
> validation. By introducing these dedicated sysctl interfaces, we provide
> a clearer and more granular way to configure the loglevels.
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Tested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Chris Down <chris@chrisdown.name>
This patch requires non-trivial changes when rebased on top of v6.19.
There have been some conflicting changes in the sysctl API, see
https://lore.kernel.org/lkml/20251016-jag-sysctl_conv-v2-0-a2f16529acc4@kernel.org/
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -235,6 +235,13 @@ extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
>
> void do_sysctl_args(void);
> bool sysctl_is_alias(char *param);
> +int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int *valp,
> + int write, void *data);
> +int do_proc_dointvec(const struct ctl_table *table, int write,
> + void *buffer, size_t *lenp, loff_t *ppos,
> + int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> + int write, void *data),
> + void *data);
> int do_proc_douintvec(const struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos,
> int (*conv)(unsigned long *lvalp,
This hunk can be removed in v6.19. There is another interface in 6.19,
see below.
> diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
> index da77f3f5c1fe..034739939a61 100644
> --- a/kernel/printk/sysctl.c
> +++ b/kernel/printk/sysctl.c
> @@ -11,6 +11,9 @@
>
> static const int ten_thousand = 10000;
>
> +static int min_msg_loglevel = LOGLEVEL_EMERG;
> +static int max_msg_loglevel = LOGLEVEL_DEBUG;
> +
> static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int write,
> void *buffer, size_t *lenp, loff_t *ppos)
> {
> @@ -20,6 +23,50 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
> return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> }
The new way is to define the needed helpers using macros. We need this:
static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
sysctl_kern_to_user_int_conv, false)
> +static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> + int *valp,
> + int write, void *data)
There parameters have got renamed and @table is passed instead or @data:
static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *u_ptr,
int *k_ptr, int dir,
const struct ctl_table *table)
> +{
> + int level, ret;
> +
> + /*
> + * If writing, first do so via a temporary local int so we can
> + * bounds-check it before touching *valp.
> + */
> + int *intp = write ? &level : valp;
The direction is newly checked by macro:
int *int_ptr = SYSCTL_USER_TO_KERN(dir) ? &level : k_ptr;
> + ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
The following helper is defined by the above mentioned macros:
ret = do_proc_int_conv(negp, u_ptr, int_ptr, dir, table);
> + if (ret)
> + return ret;
> +
> + if (write) {
The new way:
if (SYSCTL_USER_TO_KERN(dir)) {
> + if (level != console_clamp_loglevel(level))
> + return -ERANGE;
> +
> + /*
> + * Honour the administrator-configured minimum console
> + * loglevel (third element of kernel.printk). This mirrors
> + * the syslog() and sysfs control paths so that once the floor
> + * is raised we do not let this sysctl silently bypass it.
> + */
> + if (minimum_console_loglevel > CONSOLE_LOGLEVEL_MIN &&
> + level < minimum_console_loglevel)
> + level = minimum_console_loglevel;
> +
> + WRITE_ONCE(*valp, level);
New parameter name:
WRITE_ONCE(*k_ptr, level);
> + }
> +
> + return 0;
> +}
> +
> +static int proc_dointvec_console_loglevel(const struct ctl_table *table,
> + int write, void *buffer, size_t *lenp,
> + loff_t *ppos)
> +{
> + return do_proc_dointvec(table, write, buffer, lenp, ppos,
> + do_proc_dointvec_console_loglevel, NULL);
There is a new function where the last NULL parameter is not longer passed:
return proc_dointvec_conv(table, write, buffer, lenp, ppos,
do_proc_dointvec_console_loglevel);
> +}
> +
> static const struct ctl_table printk_sysctls[] = {
> {
> .procname = "printk",
Here are the above described changes made by diff:
--- a/kernel/printk/sysctl.c
+++ b/kernel/printk/sysctl.c
@@ -24,9 +24,14 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
}
-static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
- int *valp,
- int write, void *data)
+static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
+static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
+static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
+ sysctl_kern_to_user_int_conv, false)
+
+static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *u_ptr,
+ int *k_ptr, int dir,
+ const struct ctl_table *table)
{
int level, ret;
@@ -34,13 +39,13 @@ static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
* If writing, first do so via a temporary local int so we can
* bounds-check it before touching *valp.
*/
- int *intp = write ? &level : valp;
+ int *int_ptr = SYSCTL_USER_TO_KERN(dir) ? &level : k_ptr;
- ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
+ ret = do_proc_int_conv(negp, u_ptr, int_ptr, dir, table);
if (ret)
return ret;
- if (write) {
+ if (SYSCTL_USER_TO_KERN(dir)) {
if (level != console_clamp_loglevel(level))
return -ERANGE;
@@ -54,7 +59,7 @@ static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
level < minimum_console_loglevel)
level = minimum_console_loglevel;
- WRITE_ONCE(*valp, level);
+ WRITE_ONCE(*k_ptr, level);
}
return 0;
@@ -64,8 +69,8 @@ static int proc_dointvec_console_loglevel(const struct ctl_table *table,
int write, void *buffer, size_t *lenp,
loff_t *ppos)
{
- return do_proc_dointvec(table, write, buffer, lenp, ppos,
- do_proc_dointvec_console_loglevel, NULL);
+ return proc_dointvec_conv(table, write, buffer, lenp, ppos,
+ do_proc_dointvec_console_loglevel);
}
static int proc_dointvec_printk_deprecated(const struct ctl_table *table, int write,
> void __init printk_sysctl_init(void)
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index cb6196e3fa99..3ed010b8f6b3 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -354,9 +354,9 @@ static void proc_put_char(void **buf, size_t *size, char c)
> }
> }
>
> -static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> - int *valp,
> - int write, void *data)
> +int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> + int *valp,
> + int write, void *data)
> {
> if (write) {
> if (*negp) {
> @@ -380,6 +380,7 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> }
> return 0;
> }
> +EXPORT_SYMBOL(do_proc_dointvec_conv);
>
> static int do_proc_douintvec_conv(unsigned long *lvalp,
> unsigned int *valp,
> @@ -471,15 +472,16 @@ static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table,
> return err;
> }
>
> -static int do_proc_dointvec(const struct ctl_table *table, int write,
> - void *buffer, size_t *lenp, loff_t *ppos,
> - int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> - int write, void *data),
> - void *data)
> +int do_proc_dointvec(const struct ctl_table *table, int write,
> + void *buffer, size_t *lenp, loff_t *ppos,
> + int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> + int write, void *data),
> + void *data)
> {
> return __do_proc_dointvec(table->data, table, write,
> buffer, lenp, ppos, conv, data);
> }
> +EXPORT_SYMBOL(do_proc_dointvec);
>
> static int do_proc_douintvec_w(unsigned int *tbl_data,
> const struct ctl_table *table,
Also all these changes in kernel/sysctl.c are not loger needed.
Best Regards,
Petr
On Fri, Dec 12, 2025 at 04:24:17PM +0100, Petr Mladek wrote:
> Adding Joel into Cc. Joel, see the original patch at
> https://lore.kernel.org/all/c3e5cc507eb3fd7db0a002f31d7e47d764cad176.1764272407.git.chris@chrisdown.name/
Thx for adding me. Please CC me in the next versions of this series as
the interface might change (slightly) again. By having this on my radar
we can better coordinate (if needed) linux-next and PRs for Linus.
>
> On Fri 2025-11-28 03:44:25, Chris Down wrote:
> > Introduce two new sysctl interfaces for configuring global loglevels:
> >
> > - kernel.console_loglevel: Sets the global console loglevel, determining
> > the minimum priority of messages printed to consoles. Messages with a
> > loglevel lower than this value will be printed.
> > - kernel.default_message_loglevel: Sets the default loglevel for
> > messages that do not specify an explicit loglevel.
> >
> > The kernel.printk sysctl was previously used to set multiple loglevel
> > parameters simultaneously, but it was confusing and lacked proper
> > validation. By introducing these dedicated sysctl interfaces, we provide
> > a clearer and more granular way to configure the loglevels.
> >
> > Reviewed-by: Petr Mladek <pmladek@suse.com>
> > Tested-by: Petr Mladek <pmladek@suse.com>
> > Signed-off-by: Chris Down <chris@chrisdown.name>
>
> This patch requires non-trivial changes when rebased on top of v6.19.
> There have been some conflicting changes in the sysctl API, see
> https://lore.kernel.org/lkml/20251016-jag-sysctl_conv-v2-0-a2f16529acc4@kernel.org/
>
> > --- a/include/linux/sysctl.h
> > +++ b/include/linux/sysctl.h
> > @@ -235,6 +235,13 @@ extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
> >
> > void do_sysctl_args(void);
> > bool sysctl_is_alias(char *param);
> > +int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int *valp,
> > + int write, void *data);
> > +int do_proc_dointvec(const struct ctl_table *table, int write,
> > + void *buffer, size_t *lenp, loff_t *ppos,
> > + int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> > + int write, void *data),
> > + void *data);
> > int do_proc_douintvec(const struct ctl_table *table, int write,
> > void *buffer, size_t *lenp, loff_t *ppos,
> > int (*conv)(unsigned long *lvalp,
>
> This hunk can be removed in v6.19. There is another interface in 6.19,
> see below.
>
> > diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
> > index da77f3f5c1fe..034739939a61 100644
> > --- a/kernel/printk/sysctl.c
> > +++ b/kernel/printk/sysctl.c
> > @@ -11,6 +11,9 @@
> >
> > static const int ten_thousand = 10000;
> >
> > +static int min_msg_loglevel = LOGLEVEL_EMERG;
> > +static int max_msg_loglevel = LOGLEVEL_DEBUG;
> > +
> > static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int write,
> > void *buffer, size_t *lenp, loff_t *ppos)
> > {
> > @@ -20,6 +23,50 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
> > return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> > }
>
> The new way is to define the needed helpers using macros. We need this:
>
> static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
> static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
> static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
> sysctl_kern_to_user_int_conv, false)
>
>
> > +static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> > + int *valp,
> > + int write, void *data)
>
> There parameters have got renamed and @table is passed instead or @data:
>
> static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *u_ptr,
> int *k_ptr, int dir,
> const struct ctl_table *table)
>
>
> > +{
> > + int level, ret;
> > +
> > + /*
> > + * If writing, first do so via a temporary local int so we can
> > + * bounds-check it before touching *valp.
> > + */
> > + int *intp = write ? &level : valp;
>
> The direction is newly checked by macro:
>
> int *int_ptr = SYSCTL_USER_TO_KERN(dir) ? &level : k_ptr;
>
> > + ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
>
> The following helper is defined by the above mentioned macros:
>
> ret = do_proc_int_conv(negp, u_ptr, int_ptr, dir, table);
>
> > + if (ret)
> > + return ret;
> > +
> > + if (write) {
>
> The new way:
>
> if (SYSCTL_USER_TO_KERN(dir)) {
>
> > + if (level != console_clamp_loglevel(level))
> > + return -ERANGE;
> > +
> > + /*
> > + * Honour the administrator-configured minimum console
> > + * loglevel (third element of kernel.printk). This mirrors
> > + * the syslog() and sysfs control paths so that once the floor
> > + * is raised we do not let this sysctl silently bypass it.
> > + */
> > + if (minimum_console_loglevel > CONSOLE_LOGLEVEL_MIN &&
> > + level < minimum_console_loglevel)
> > + level = minimum_console_loglevel;
> > +
> > + WRITE_ONCE(*valp, level);
>
> New parameter name:
>
> WRITE_ONCE(*k_ptr, level);
>
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int proc_dointvec_console_loglevel(const struct ctl_table *table,
> > + int write, void *buffer, size_t *lenp,
> > + loff_t *ppos)
> > +{
> > + return do_proc_dointvec(table, write, buffer, lenp, ppos,
> > + do_proc_dointvec_console_loglevel, NULL);
>
> There is a new function where the last NULL parameter is not longer passed:
>
> return proc_dointvec_conv(table, write, buffer, lenp, ppos,
> do_proc_dointvec_console_loglevel);
>
> > +}
> > +
> > static const struct ctl_table printk_sysctls[] = {
> > {
> > .procname = "printk",
>
>
> Here are the above described changes made by diff:
The changes look ok, but there is a lot of context that I'm missing from
just looking at this change. Will there be another version re-based on
top of v19-rc1?
>
> --- a/kernel/printk/sysctl.c
> +++ b/kernel/printk/sysctl.c
> @@ -24,9 +24,14 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
> return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> }
>
> -static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> - int *valp,
> - int write, void *data)
> +static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
> +static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
> +static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
> + sysctl_kern_to_user_int_conv, false)
> +
> +static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *u_ptr,
> + int *k_ptr, int dir,
> + const struct ctl_table *table)
> {
> int level, ret;
>
> @@ -34,13 +39,13 @@ static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> * If writing, first do so via a temporary local int so we can
> * bounds-check it before touching *valp.
> */
> - int *intp = write ? &level : valp;
> + int *int_ptr = SYSCTL_USER_TO_KERN(dir) ? &level : k_ptr;
>
> - ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
> + ret = do_proc_int_conv(negp, u_ptr, int_ptr, dir, table);
> if (ret)
> return ret;
>
> - if (write) {
> + if (SYSCTL_USER_TO_KERN(dir)) {
> if (level != console_clamp_loglevel(level))
> return -ERANGE;
>
> @@ -54,7 +59,7 @@ static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> level < minimum_console_loglevel)
> level = minimum_console_loglevel;
>
> - WRITE_ONCE(*valp, level);
> + WRITE_ONCE(*k_ptr, level);
> }
>
> return 0;
> @@ -64,8 +69,8 @@ static int proc_dointvec_console_loglevel(const struct ctl_table *table,
> int write, void *buffer, size_t *lenp,
> loff_t *ppos)
> {
> - return do_proc_dointvec(table, write, buffer, lenp, ppos,
> - do_proc_dointvec_console_loglevel, NULL);
> + return proc_dointvec_conv(table, write, buffer, lenp, ppos,
> + do_proc_dointvec_console_loglevel);
> }
>
> static int proc_dointvec_printk_deprecated(const struct ctl_table *table, int write,
>
>
> > void __init printk_sysctl_init(void)
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index cb6196e3fa99..3ed010b8f6b3 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -354,9 +354,9 @@ static void proc_put_char(void **buf, size_t *size, char c)
> > }
> > }
> >
> > -static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> > - int *valp,
> > - int write, void *data)
> > +int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> > + int *valp,
> > + int write, void *data)
> > {
> > if (write) {
> > if (*negp) {
> > @@ -380,6 +380,7 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp,
> > }
> > return 0;
> > }
> > +EXPORT_SYMBOL(do_proc_dointvec_conv);
> >
> > static int do_proc_douintvec_conv(unsigned long *lvalp,
> > unsigned int *valp,
> > @@ -471,15 +472,16 @@ static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table,
> > return err;
> > }
> >
> > -static int do_proc_dointvec(const struct ctl_table *table, int write,
> > - void *buffer, size_t *lenp, loff_t *ppos,
> > - int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> > - int write, void *data),
> > - void *data)
> > +int do_proc_dointvec(const struct ctl_table *table, int write,
> > + void *buffer, size_t *lenp, loff_t *ppos,
> > + int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> > + int write, void *data),
> > + void *data)
> > {
> > return __do_proc_dointvec(table->data, table, write,
> > buffer, lenp, ppos, conv, data);
> > }
> > +EXPORT_SYMBOL(do_proc_dointvec);
> >
> > static int do_proc_douintvec_w(unsigned int *tbl_data,
> > const struct ctl_table *table,
>
> Also all these changes in kernel/sysctl.c are not loger needed.
>
> Best Regards,
> Petr
--
Joel Granados
On Mon 2025-12-15 11:08:12, Joel Granados wrote:
> On Fri, Dec 12, 2025 at 04:24:17PM +0100, Petr Mladek wrote:
> > Adding Joel into Cc. Joel, see the original patch at
> > https://lore.kernel.org/all/c3e5cc507eb3fd7db0a002f31d7e47d764cad176.1764272407.git.chris@chrisdown.name/
> Thx for adding me. Please CC me in the next versions of this series as
> the interface might change (slightly) again. By having this on my radar
> we can better coordinate (if needed) linux-next and PRs for Linus.
> >
> > On Fri 2025-11-28 03:44:25, Chris Down wrote:
> > > Introduce two new sysctl interfaces for configuring global loglevels:
> > >
> > > --- a/include/linux/sysctl.h
> > > +++ b/include/linux/sysctl.h
> > > @@ -235,6 +235,13 @@ extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
> > >
> > > void do_sysctl_args(void);
> > > bool sysctl_is_alias(char *param);
> > > +int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int *valp,
> > > + int write, void *data);
> > > +int do_proc_dointvec(const struct ctl_table *table, int write,
> > > + void *buffer, size_t *lenp, loff_t *ppos,
> > > + int (*conv)(bool *negp, unsigned long *lvalp, int *valp,
> > > + int write, void *data),
> > > + void *data);
> > > int do_proc_douintvec(const struct ctl_table *table, int write,
> > > void *buffer, size_t *lenp, loff_t *ppos,
> > > int (*conv)(unsigned long *lvalp,
> >
> > This hunk can be removed in v6.19. There is another interface in 6.19,
> > see below.
> >
> > > diff --git a/kernel/printk/sysctl.c b/kernel/printk/sysctl.c
> > > index da77f3f5c1fe..034739939a61 100644
> > > --- a/kernel/printk/sysctl.c
> > > +++ b/kernel/printk/sysctl.c
> > > @@ -11,6 +11,9 @@
> > >
> > > static const int ten_thousand = 10000;
> > >
> > > +static int min_msg_loglevel = LOGLEVEL_EMERG;
> > > +static int max_msg_loglevel = LOGLEVEL_DEBUG;
> > > +
> > > static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int write,
> > > void *buffer, size_t *lenp, loff_t *ppos)
> > > {
> > > @@ -20,6 +23,50 @@ static int proc_dointvec_minmax_sysadmin(const struct ctl_table *table, int writ
> > > return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
> > > }
> >
> > The new way is to define the needed helpers using macros. We need this:
> >
> > static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
> > static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
> > static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
> > sysctl_kern_to_user_int_conv, false)
> >
> >
> > > +static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *lvalp,
> > > + int *valp,
> > > + int write, void *data)
> >
> > There parameters have got renamed and @table is passed instead or @data:
> >
> > static int do_proc_dointvec_console_loglevel(bool *negp, unsigned long *u_ptr,
> > int *k_ptr, int dir,
> > const struct ctl_table *table)
> >
> >
> > > +{
> > > + int level, ret;
> > > +
> > > + /*
> > > + * If writing, first do so via a temporary local int so we can
> > > + * bounds-check it before touching *valp.
> > > + */
> > > + int *intp = write ? &level : valp;
> >
> > The direction is newly checked by macro:
> >
> > int *int_ptr = SYSCTL_USER_TO_KERN(dir) ? &level : k_ptr;
> >
> > > + ret = do_proc_dointvec_conv(negp, lvalp, intp, write, data);
> >
> > The following helper is defined by the above mentioned macros:
> >
> > ret = do_proc_int_conv(negp, u_ptr, int_ptr, dir, table);
> >
> > > + if (ret)
> > > + return ret;
> > > +
> > > + if (write) {
> >
> > The new way:
> >
> > if (SYSCTL_USER_TO_KERN(dir)) {
> >
> > > + if (level != console_clamp_loglevel(level))
> > > + return -ERANGE;
> > > +
> > > + /*
> > > + * Honour the administrator-configured minimum console
> > > + * loglevel (third element of kernel.printk). This mirrors
> > > + * the syslog() and sysfs control paths so that once the floor
> > > + * is raised we do not let this sysctl silently bypass it.
> > > + */
> > > + if (minimum_console_loglevel > CONSOLE_LOGLEVEL_MIN &&
> > > + level < minimum_console_loglevel)
> > > + level = minimum_console_loglevel;
> > > +
> > > + WRITE_ONCE(*valp, level);
> >
> > New parameter name:
> >
> > WRITE_ONCE(*k_ptr, level);
> >
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int proc_dointvec_console_loglevel(const struct ctl_table *table,
> > > + int write, void *buffer, size_t *lenp,
> > > + loff_t *ppos)
> > > +{
> > > + return do_proc_dointvec(table, write, buffer, lenp, ppos,
> > > + do_proc_dointvec_console_loglevel, NULL);
> >
> > There is a new function where the last NULL parameter is not longer passed:
> >
> > return proc_dointvec_conv(table, write, buffer, lenp, ppos,
> > do_proc_dointvec_console_loglevel);
> >
> > > +}
> > > +
> > > static const struct ctl_table printk_sysctls[] = {
> > > {
> > > .procname = "printk",
> >
> >
> > Here are the above described changes made by diff:
> The changes look ok,
Great.
> but there is a lot of context that I'm missing from
> just looking at this change. Will there be another version re-based on
> top of v19-rc1?
Yes, we need v9. Chris, please add Joel into Cc.
Thanks a lot for checking.
Best Regards,
Petr
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