[PATCH 3/3] kernel/hung_task convert hung_task_panic boot parameter to sysctl

Vlastimil Babka
2020-03-30T11:56:06Z

We can now handle sysctl parameters on kernel command line and have
infrastructure to convert legacy command line options that duplicate sysctl
to become a sysctl alias.

This patch converts the hung_task_panic parameter. Note that the sysctl handler
is more strict and allows only 0 and 1, while the legacy parameter allowed
any non-zero value. But there is little reason anyone would not be using 1.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
Documentation/admin-guide/kernel-parameters.txt | 2 +-
fs/proc/proc_sysctl.c | 1 +
kernel/hung_task.c | 10 ----------
3 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 81ff626fc700..e0b8840404a1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1457,7 +1457,7 @@
[KNL] Should the hung task detector generate panics.
Format: <integer>

- A nonzero value instructs the kernel to panic when a
+ A value of 1 instructs the kernel to panic when a
hung task is detected. The default value is controlled
by the CONFIG_BOOTPARAM_HUNG_TASK_PANIC build-time
option. The value selected by this boot parameter can
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 97eb0b552bf8..77b1b844b02b 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1743,6 +1743,7 @@ struct sysctl_alias {
*/
static const struct sysctl_alias sysctl_aliases[] = {
{"numa_zonelist_order", "vm.numa_zonelist_order" },
+ {"hung_task_panic", "kernel.hung_task_panic" },
{ }
};

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 14a625c16cb3..b22b5eeab3cb 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -63,16 +63,6 @@ static struct task_struct *watchdog_task;
unsigned int __read_mostly sysctl_hung_task_panic =
CONFIG_BOOTPARAM_HUNG_TASK_PANIC_VALUE;

-static int __init hung_task_panic_setup(char *str)
-{
- int rc = kstrtouint(str, 0, &sysctl_hung_task_panic);
-
- if (rc)
- return rc;
- return 1;
-}
-__setup("hung_task_panic=", hung_task_panic_setup);
-
static int
hung_task_panic(struct notifier_block *this, unsigned long event, void *ptr)
{
--
2.25.1