Re: [PATCH v2] treewide: const qualify ctl_tables where applicable

Alexander Gordeev
2025-01-21T13:40:56Z

On Fri, Jan 10, 2025 at 03:16:08PM +0100, Joel Granados wrote:

Hi Joel,

> Add the const qualifier to all the ctl_tables in the tree except for
> watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
> loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
> drivers/inifiniband dirs). These are special cases as they use a
> registration function with a non-const qualified ctl_table argument or
> modify the arrays before passing them on to the registration function.
>
> Constifying ctl_table structs will prevent the modification of
> proc_handler function pointers as the arrays would reside in .rodata.
> This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
> constify the ctl_table argument of proc_handlers") constified all the
> proc_handlers.

I could identify at least these occurences in s390 code as well:

diff --git a/arch/s390/appldata/appldata_base.c b/arch/s390/appldata/appldata_base.c
index dd7ba7587dd5..9b83c318f919 100644
--- a/arch/s390/appldata/appldata_base.c
+++ b/arch/s390/appldata/appldata_base.c
@@ -204,7 +204,7 @@ appldata_timer_handler(const struct ctl_table *ctl, int write,
{
int timer_active = appldata_timer_active;
int rc;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &timer_active,
.maxlen = sizeof(int),
@@ -237,7 +237,7 @@ appldata_interval_handler(const struct ctl_table *ctl, int write,
{
int interval = appldata_interval;
int rc;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &interval,
.maxlen = sizeof(int),
@@ -269,7 +269,7 @@ appldata_generic_handler(const struct ctl_table *ctl, int write,
struct list_head *lh;
int rc, found;
int active;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.data = &active,
.maxlen = sizeof(int),
.extra1 = SYSCTL_ZERO,
diff --git a/arch/s390/kernel/hiperdispatch.c b/arch/s390/kernel/hiperdispatch.c
index 7857a7e8e56c..7d0ba16085c1 100644
--- a/arch/s390/kernel/hiperdispatch.c
+++ b/arch/s390/kernel/hiperdispatch.c
@@ -273,7 +273,7 @@ static int hiperdispatch_ctl_handler(const struct ctl_table *ctl, int write,
{
int hiperdispatch;
int rc;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &hiperdispatch,
.maxlen = sizeof(int),
diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index 6691808bf50a..26e50de83d80 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c
@@ -629,7 +629,7 @@ static int topology_ctl_handler(const struct ctl_table *ctl, int write,
int enabled = topology_is_enabled();
int new_mode;
int rc;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &enabled,
.maxlen = sizeof(int),
@@ -658,7 +658,7 @@ static int polarization_ctl_handler(const struct ctl_table *ctl, int write,
{
int polarization;
int rc;
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &polarization,
.maxlen = sizeof(int),
diff --git a/arch/s390/mm/cmm.c b/arch/s390/mm/cmm.c
index 939e3bec2db7..8e354c90a3dd 100644
--- a/arch/s390/mm/cmm.c
+++ b/arch/s390/mm/cmm.c
@@ -263,7 +263,7 @@ static int cmm_pages_handler(const struct ctl_table *ctl, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
long nr = cmm_get_pages();
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &nr,
.maxlen = sizeof(long),
@@ -283,7 +283,7 @@ static int cmm_timed_pages_handler(const struct ctl_table *ctl, int write,
loff_t *ppos)
{
long nr = cmm_get_timed_pages();
- struct ctl_table ctl_entry = {
+ const struct ctl_table ctl_entry = {
.procname = ctl->procname,
.data = &nr,
.maxlen = sizeof(long),

> Best regards,
> --
> Joel Granados <joel.granados@kernel.org>

Thanks!