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Commit 84a78a65 authored by Nathan Zimmer's avatar Nathan Zimmer Committed by Linus Torvalds
Browse files

timer_list: correct the iterator for timer_list 



Correct an issue with /proc/timer_list reported by Holger.

When reading from the proc file with a sufficiently small buffer, 2k so
not really that small, there was one could get hung trying to read the
file a chunk at a time.

The timer_list_start function failed to account for the possibility that
the offset was adjusted outside the timer_list_next.

Signed-off-by: default avatarNathan Zimmer <nzimmer@sgi.com>
Reported-by: default avatarHolger Hans Peter Freyther <holger@freyther.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Berke Durak <berke.durak@xiphos.com>
Cc: Jeff Layton <jlayton@redhat.com>
Tested-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org> # 3.10.x
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fa8218de

kernel/time/timer_list.c

+24 −17
Original line number Diff line number Diff line
@@ -265,10 +265,9 @@ static inline void timer_list_header(struct seq_file *m, u64 now) 
static int timer_list_show(struct seq_file *m, void *v)

{

	struct timer_list_iter *iter = v;

	u64 now = ktime_to_ns(ktime_get());



	if (iter->cpu == -1 && !iter->second_pass)

		timer_list_header(m, now);

		timer_list_header(m, iter->now);

	else if (!iter->second_pass)

		print_cpu(m, iter->cpu, iter->now);

#ifdef CONFIG_GENERIC_CLOCKEVENTS
@@ -298,14 +297,11 @@ void sysrq_timer_list_show(void) 
	return;

}



static void *timer_list_start(struct seq_file *file, loff_t *offset)

static void *move_iter(struct timer_list_iter *iter, loff_t offset)

{

	struct timer_list_iter *iter = file->private;



	if (!*offset) {

		iter->cpu = -1;

		iter->now = ktime_to_ns(ktime_get());

	} else if (iter->cpu >= nr_cpu_ids) {

	for (; offset; offset--) {

		iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);

		if (iter->cpu >= nr_cpu_ids) {

#ifdef CONFIG_GENERIC_CLOCKEVENTS

			if (!iter->second_pass) {

				iter->cpu = -1;
@@ -316,15 +312,26 @@ static void *timer_list_start(struct seq_file *file, loff_t *offset) 
			return NULL;

#endif

		}

	}

	return iter;

}



static void *timer_list_start(struct seq_file *file, loff_t *offset)

{

	struct timer_list_iter *iter = file->private;



	if (!*offset)

		iter->now = ktime_to_ns(ktime_get());

	iter->cpu = -1;

	iter->second_pass = false;

	return move_iter(iter, *offset);

}



static void *timer_list_next(struct seq_file *file, void *v, loff_t *offset)

{

	struct timer_list_iter *iter = file->private;

	iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);

	++*offset;

	return timer_list_start(file, offset);

	return move_iter(iter, 1);

}



static void timer_list_stop(struct seq_file *seq, void *v)