[PATCH v4 3/4] hung_task: Move hung_task sysctl interface to hung_task.c

From: Xiaoming Ni
Date: Mon May 18 2020 - 23:31:32 EST


Move hung_task sysctl interface to hung_task.c.
Use register_sysctl() to register the sysctl interface to avoid
merge conflicts when different features modify sysctl.c at the same time.

Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
include/linux/sched/sysctl.h | 14 +-------
kernel/hung_task.c | 77 +++++++++++++++++++++++++++++++++++++++++++-
kernel/sysctl.c | 62 -----------------------------------
3 files changed, 77 insertions(+), 76 deletions(-)

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 660ac49..fcd397a8 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -7,20 +7,8 @@
struct ctl_table;

#ifdef CONFIG_DETECT_HUNG_TASK
-
-#ifdef CONFIG_SMP
-extern unsigned int sysctl_hung_task_all_cpu_backtrace;
-#else
-#define sysctl_hung_task_all_cpu_backtrace 0
-#endif /* CONFIG_SMP */
-
-extern int sysctl_hung_task_check_count;
-extern unsigned int sysctl_hung_task_panic;
+/* used for hung_task and block/ */
extern unsigned long sysctl_hung_task_timeout_secs;
-extern unsigned long sysctl_hung_task_check_interval_secs;
-extern int sysctl_hung_task_warnings;
-int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
- void *buffer, size_t *lenp, loff_t *ppos);
#else
/* Avoid need for ifdefs elsewhere in the code */
enum { sysctl_hung_task_timeout_secs = 0 };
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index a672db8..d67df599 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -63,6 +63,9 @@
* Defaults to 0, can be changed via sysctl.
*/
unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace;
+#else
+/* Avoid need for ifdefs elsewhere in the code */
+enum { sysctl_hung_task_timeout_secs = 0 };
#endif /* CONFIG_SMP */

/*
@@ -265,10 +268,11 @@ static long hung_timeout_jiffies(unsigned long last_checked,
MAX_SCHEDULE_TIMEOUT;
}

+#ifdef CONFIG_SYSCTL
/*
* Process updating of timeout sysctl
*/
-int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
+static int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
void __user *buffer,
size_t *lenp, loff_t *ppos)
{
@@ -285,6 +289,76 @@ int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
return ret;
}

+/*
+ * This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs
+ * and hung_task_check_interval_secs
+ */
+static const unsigned long hung_task_timeout_max = (LONG_MAX / HZ);
+static struct ctl_table hung_task_sysctls[] = {
+#ifdef CONFIG_SMP
+ {
+ .procname = "hung_task_all_cpu_backtrace",
+ .data = &sysctl_hung_task_all_cpu_backtrace,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+#endif /* CONFIG_SMP */
+ {
+ .procname = "hung_task_panic",
+ .data = &sysctl_hung_task_panic,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
+ {
+ .procname = "hung_task_check_count",
+ .data = &sysctl_hung_task_check_count,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ },
+ {
+ .procname = "hung_task_timeout_secs",
+ .data = &sysctl_hung_task_timeout_secs,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_dohung_task_timeout_secs,
+ .extra2 = (void *)&hung_task_timeout_max,
+ },
+ {
+ .procname = "hung_task_check_interval_secs",
+ .data = &sysctl_hung_task_check_interval_secs,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = proc_dohung_task_timeout_secs,
+ .extra2 = (void *)&hung_task_timeout_max,
+ },
+ {
+ .procname = "hung_task_warnings",
+ .data = &sysctl_hung_task_warnings,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = SYSCTL_NEG_ONE,
+ },
+ {}
+};
+
+static void __init hung_task_sysctl_init(void)
+{
+ register_sysctl_init("kernel", hung_task_sysctls, "hung_task_sysctls");
+}
+#else
+#define hung_task_sysctl_init() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
+
static atomic_t reset_hung_task = ATOMIC_INIT(0);

void reset_hung_task_detector(void)
@@ -354,6 +428,7 @@ static int __init hung_task_init(void)
pm_notifier(hungtask_pm_notify, 0);

watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
+ hung_task_sysctl_init();

return 0;
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 38469bf..b7fd4e6 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -131,13 +131,6 @@
static const int ngroups_max = NGROUPS_MAX;
static const int cap_last_cap = CAP_LAST_CAP;

-/*
- * This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs
- * and hung_task_check_interval_secs
- */
-#ifdef CONFIG_DETECT_HUNG_TASK
-static unsigned long hung_task_timeout_max = (LONG_MAX/HZ);
-#endif

#ifdef CONFIG_INOTIFY_USER
#include <linux/inotify.h>
@@ -229,7 +222,6 @@ static int bpf_stats_handler(struct ctl_table *table, int write,
return ret;
}
#endif
-
/*
* /proc/sys support
*/
@@ -2431,60 +2423,6 @@ int proc_do_static_key(struct ctl_table *table, int write,
.proc_handler = proc_dointvec,
},
#endif
-#ifdef CONFIG_DETECT_HUNG_TASK
-#ifdef CONFIG_SMP
- {
- .procname = "hung_task_all_cpu_backtrace",
- .data = &sysctl_hung_task_all_cpu_backtrace,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
-#endif /* CONFIG_SMP */
- {
- .procname = "hung_task_panic",
- .data = &sysctl_hung_task_panic,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- .extra2 = SYSCTL_ONE,
- },
- {
- .procname = "hung_task_check_count",
- .data = &sysctl_hung_task_check_count,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_ZERO,
- },
- {
- .procname = "hung_task_timeout_secs",
- .data = &sysctl_hung_task_timeout_secs,
- .maxlen = sizeof(unsigned long),
- .mode = 0644,
- .proc_handler = proc_dohung_task_timeout_secs,
- .extra2 = &hung_task_timeout_max,
- },
- {
- .procname = "hung_task_check_interval_secs",
- .data = &sysctl_hung_task_check_interval_secs,
- .maxlen = sizeof(unsigned long),
- .mode = 0644,
- .proc_handler = proc_dohung_task_timeout_secs,
- .extra2 = &hung_task_timeout_max,
- },
- {
- .procname = "hung_task_warnings",
- .data = &sysctl_hung_task_warnings,
- .maxlen = sizeof(int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = SYSCTL_NEG_ONE,
- },
-#endif
#ifdef CONFIG_RT_MUTEXES
{
.procname = "max_lock_depth",
--
1.8.5.6