time: Remove CONFIG_TIMER_STATS

Currently CONFIG_TIMER_STATS exposes process information across namespaces:

kernel/time/timer_list.c print_timer():

        SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);

/proc/timer_list:

 #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570

Given that the tracer can give the same information, this patch entirely
removes CONFIG_TIMER_STATS.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-doc@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Xing Gao <xgao01@email.wm.edu>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jessica Frazelle <me@jessfraz.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Marek <mmarek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 2 insertions, 46 deletions

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index ec33a6933eae..82a6bfa0c307 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -571,38 +571,6 @@ internal_add_timer(struct timer_base *base, struct timer_list *timer)
 	trigger_dyntick_cpu(base, timer);
 }
 
-#ifdef CONFIG_TIMER_STATS
-void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
-{
-	if (timer->start_site)
-		return;
-
-	timer->start_site = addr;
-	memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
-	timer->start_pid = current->pid;
-}
-
-static void timer_stats_account_timer(struct timer_list *timer)
-{
-	void *site;
-
-	/*
-	 * start_site can be concurrently reset by
-	 * timer_stats_timer_clear_start_info()
-	 */
-	site = READ_ONCE(timer->start_site);
-	if (likely(!site))
-		return;
-
-	timer_stats_update_stats(timer, timer->start_pid, site,
-				 timer->function, timer->start_comm,
-				 timer->flags);
-}
-
-#else
-static void timer_stats_account_timer(struct timer_list *timer) {}
-#endif
-
 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 
 static struct debug_obj_descr timer_debug_descr;
@@ -789,11 +757,6 @@ static void do_init_timer(struct timer_list *timer, unsigned int flags,
 {
 	timer->entry.pprev = NULL;
 	timer->flags = flags | raw_smp_processor_id();
-#ifdef CONFIG_TIMER_STATS
-	timer->start_site = NULL;
-	timer->start_pid = -1;
-	memset(timer->start_comm, 0, TASK_COMM_LEN);
-#endif
 	lockdep_init_map(&timer->lockdep_map, name, key, 0);
 }
 
@@ -1001,8 +964,6 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 		base = lock_timer_base(timer, &flags);
 	}
 
-	timer_stats_timer_set_start_info(timer);
-
 	ret = detach_if_pending(timer, base, false);
 	if (!ret && pending_only)
 		goto out_unlock;
@@ -1130,7 +1091,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
 	struct timer_base *new_base, *base;
 	unsigned long flags;
 
-	timer_stats_timer_set_start_info(timer);
 	BUG_ON(timer_pending(timer) || !timer->function);
 
 	new_base = get_timer_cpu_base(timer->flags, cpu);
@@ -1176,7 +1136,6 @@ int del_timer(struct timer_list *timer)
 
 	debug_assert_init(timer);
 
-	timer_stats_timer_clear_start_info(timer);
 	if (timer_pending(timer)) {
 		base = lock_timer_base(timer, &flags);
 		ret = detach_if_pending(timer, base, true);
@@ -1204,10 +1163,9 @@ int try_to_del_timer_sync(struct timer_list *timer)
 
 	base = lock_timer_base(timer, &flags);
 
-	if (base->running_timer != timer) {
-		timer_stats_timer_clear_start_info(timer);
+	if (base->running_timer != timer)
 		ret = detach_if_pending(timer, base, true);
-	}
+
 	spin_unlock_irqrestore(&base->lock, flags);
 
 	return ret;
@@ -1331,7 +1289,6 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
 		unsigned long data;
 
 		timer = hlist_entry(head->first, struct timer_list, entry);
-		timer_stats_account_timer(timer);
 
 		base->running_timer = timer;
 		detach_timer(timer, true);
@@ -1868,7 +1825,6 @@ static void __init init_timer_cpus(void)
 void __init init_timers(void)
 {
 	init_timer_cpus();
-	init_timer_stats();
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }