[PATCH 5/8] events: Move perf_event sysctls into kernel/events

[Joel Granados <joel.granados@kernel.org>]

Move ctl tables to two files:
* perf_event_{paranoid,mlock_kb,max_sample_rate} and
  perf_cpu_time_max_percent into kernel/events/core.c
* perf_event_max_{stack,context_per_stack} into
  kernel/events/callchain.c

Make static variables and functions that are fully contained in core.c
and callchain.cand remove them from include/linux/perf_event.h.
Additionally six_hundred_forty_kb is moved to callchain.c.

Two new sysctl tables are added ({callchain,events_core}_sysctl_table)
with their respective sysctl registration functions.

This is part of a greater effort to move ctl tables into their
respective subsystems which will reduce the merge conflicts in
kerenel/sysctl.c.

Signed-off-by: Joel Granados <joel.granados@kernel.org>
---
 include/linux/perf_event.h |  9 -------
 kernel/events/callchain.c  | 38 ++++++++++++++++++++++-----
 kernel/events/core.c       | 57 ++++++++++++++++++++++++++++++++++++-----
 kernel/sysctl.c            | 64 ----------------------------------------------
 4 files changed, 83 insertions(+), 85 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 8333f132f4a9..a92ade5d62be 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1646,19 +1646,10 @@ static inline int perf_callchain_store(struct perf_callchain_entry_ctx *ctx, u64
 }
 
 extern int sysctl_perf_event_paranoid;
-extern int sysctl_perf_event_mlock;
 extern int sysctl_perf_event_sample_rate;
-extern int sysctl_perf_cpu_time_max_percent;
 
 extern void perf_sample_event_took(u64 sample_len_ns);
 
-int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write,
-		void *buffer, size_t *lenp, loff_t *ppos);
-int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write,
-		void *buffer, size_t *lenp, loff_t *ppos);
-int perf_event_max_stack_handler(const struct ctl_table *table, int write,
-		void *buffer, size_t *lenp, loff_t *ppos);
-
 /* Access to perf_event_open(2) syscall. */
 #define PERF_SECURITY_OPEN		0
 
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 8a47e52a454f..6c83ad674d01 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -22,6 +22,7 @@ struct callchain_cpus_entries {
 
 int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
 int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK;
+static const int six_hundred_forty_kb = 640 * 1024;
 
 static inline size_t perf_callchain_entry__sizeof(void)
 {
@@ -266,12 +267,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
 	return entry;
 }
 
-/*
- * Used for sysctl_perf_event_max_stack and
- * sysctl_perf_event_max_contexts_per_stack.
- */
-int perf_event_max_stack_handler(const struct ctl_table *table, int write,
-				 void *buffer, size_t *lenp, loff_t *ppos)
+static int perf_event_max_stack_handler(const struct ctl_table *table, int write,
+					void *buffer, size_t *lenp, loff_t *ppos)
 {
 	int *value = table->data;
 	int new_value = *value, ret;
@@ -292,3 +289,32 @@ int perf_event_max_stack_handler(const struct ctl_table *table, int write,
 
 	return ret;
 }
+
+static const struct ctl_table callchain_sysctl_table[] = {
+	{
+		.procname	= "perf_event_max_stack",
+		.data		= &sysctl_perf_event_max_stack,
+		.maxlen		= sizeof(sysctl_perf_event_max_stack),
+		.mode		= 0644,
+		.proc_handler	= perf_event_max_stack_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= (void *)&six_hundred_forty_kb,
+	},
+	{
+		.procname	= "perf_event_max_contexts_per_stack",
+		.data		= &sysctl_perf_event_max_contexts_per_stack,
+		.maxlen		= sizeof(sysctl_perf_event_max_contexts_per_stack),
+		.mode		= 0644,
+		.proc_handler	= perf_event_max_stack_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE_THOUSAND,
+	},
+};
+
+static int __init init_callchain_sysctls(void)
+{
+	register_sysctl_init("kernel", callchain_sysctl_table);
+	return 0;
+}
+core_initcall(init_callchain_sysctls);
+
diff --git a/kernel/events/core.c b/kernel/events/core.c
index bcb09e011e9e..3c3d95312c28 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -452,8 +452,8 @@ static struct kmem_cache *perf_event_cache;
  */
 int sysctl_perf_event_paranoid __read_mostly = 2;
 
-/* Minimum for 512 kiB + 1 user control page */
-int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
+/* Minimum for 512 kiB + 1 user control page. 'free' kiB per user. */
+static int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024);
 
 /*
  * max perf event sample rate
@@ -463,6 +463,7 @@ int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free'
 #define DEFAULT_CPU_TIME_MAX_PERCENT	25
 
 int sysctl_perf_event_sample_rate __read_mostly	= DEFAULT_MAX_SAMPLE_RATE;
+static int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT;
 
 static int max_samples_per_tick __read_mostly	= DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
 static int perf_sample_period_ns __read_mostly	= DEFAULT_SAMPLE_PERIOD_NS;
@@ -484,7 +485,7 @@ static void update_perf_cpu_limits(void)
 
 static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc);
 
-int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write,
+static int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write,
 				       void *buffer, size_t *lenp, loff_t *ppos)
 {
 	int ret;
@@ -506,9 +507,7 @@ int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write,
 	return 0;
 }
 
-int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT;
-
-int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write,
+static int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write,
 		void *buffer, size_t *lenp, loff_t *ppos)
 {
 	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
@@ -528,6 +527,52 @@ int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write,
 	return 0;
 }
 
+static const struct ctl_table events_core_sysctl_table[] = {
+	/*
+	 * User-space relies on this file as a feature check for
+	 * perf_events being enabled. It's an ABI, do not remove!
+	 */
+	{
+		.procname	= "perf_event_paranoid",
+		.data		= &sysctl_perf_event_paranoid,
+		.maxlen		= sizeof(sysctl_perf_event_paranoid),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "perf_event_mlock_kb",
+		.data		= &sysctl_perf_event_mlock,
+		.maxlen		= sizeof(sysctl_perf_event_mlock),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "perf_event_max_sample_rate",
+		.data		= &sysctl_perf_event_sample_rate,
+		.maxlen		= sizeof(sysctl_perf_event_sample_rate),
+		.mode		= 0644,
+		.proc_handler	= perf_event_max_sample_rate_handler,
+		.extra1		= SYSCTL_ONE,
+	},
+	{
+		.procname	= "perf_cpu_time_max_percent",
+		.data		= &sysctl_perf_cpu_time_max_percent,
+		.maxlen		= sizeof(sysctl_perf_cpu_time_max_percent),
+		.mode		= 0644,
+		.proc_handler	= perf_cpu_time_max_percent_handler,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE_HUNDRED,
+	},
+};
+
+static int __init init_events_core_sysctls(void)
+{
+	register_sysctl_init("kernel", events_core_sysctl_table);
+	return 0;
+}
+core_initcall(init_events_core_sysctls);
+
+
 /*
  * perf samples are done in some very critical code paths (NMIs).
  * If they take too much CPU time, the system can lock up and not
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index dc3747cc72d4..fdc92d80e841 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -51,7 +51,6 @@
 #include <linux/nfs_fs.h>
 #include <linux/acpi.h>
 #include <linux/reboot.h>
-#include <linux/perf_event.h>
 #include <linux/oom.h>
 #include <linux/kmod.h>
 #include <linux/capability.h>
@@ -87,12 +86,6 @@ EXPORT_SYMBOL_GPL(sysctl_long_vals);
 #if defined(CONFIG_SYSCTL)
 
 /* Constants used for minimum and maximum */
-
-#ifdef CONFIG_PERF_EVENTS
-static const int six_hundred_forty_kb = 640 * 1024;
-#endif
-
-
 static const int ngroups_max = NGROUPS_MAX;
 static const int cap_last_cap = CAP_LAST_CAP;
 
@@ -1869,63 +1862,6 @@ static const struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_PERF_EVENTS
-	/*
-	 * User-space scripts rely on the existence of this file
-	 * as a feature check for perf_events being enabled.
-	 *
-	 * So it's an ABI, do not remove!
-	 */
-	{
-		.procname	= "perf_event_paranoid",
-		.data		= &sysctl_perf_event_paranoid,
-		.maxlen		= sizeof(sysctl_perf_event_paranoid),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
-	{
-		.procname	= "perf_event_mlock_kb",
-		.data		= &sysctl_perf_event_mlock,
-		.maxlen		= sizeof(sysctl_perf_event_mlock),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
-	{
-		.procname	= "perf_event_max_sample_rate",
-		.data		= &sysctl_perf_event_sample_rate,
-		.maxlen		= sizeof(sysctl_perf_event_sample_rate),
-		.mode		= 0644,
-		.proc_handler	= perf_event_max_sample_rate_handler,
-		.extra1		= SYSCTL_ONE,
-	},
-	{
-		.procname	= "perf_cpu_time_max_percent",
-		.data		= &sysctl_perf_cpu_time_max_percent,
-		.maxlen		= sizeof(sysctl_perf_cpu_time_max_percent),
-		.mode		= 0644,
-		.proc_handler	= perf_cpu_time_max_percent_handler,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE_HUNDRED,
-	},
-	{
-		.procname	= "perf_event_max_stack",
-		.data		= &sysctl_perf_event_max_stack,
-		.maxlen		= sizeof(sysctl_perf_event_max_stack),
-		.mode		= 0644,
-		.proc_handler	= perf_event_max_stack_handler,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= (void *)&six_hundred_forty_kb,
-	},
-	{
-		.procname	= "perf_event_max_contexts_per_stack",
-		.data		= &sysctl_perf_event_max_contexts_per_stack,
-		.maxlen		= sizeof(sysctl_perf_event_max_contexts_per_stack),
-		.mode		= 0644,
-		.proc_handler	= perf_event_max_stack_handler,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE_THOUSAND,
-	},
-#endif
 #ifdef CONFIG_TREE_RCU
 	{
 		.procname	= "panic_on_rcu_stall",

-- 
2.44.2