From: Nathan Zimmer <nzimmer@xxxxxxx>
Subject: timer_list: correct the iterator for timer_list
Correct the 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: Nathan Zimmer <nzimmer@xxxxxxx>
Reported-by: Holger Hans Peter Freyther <holger@xxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Berke Durak <berke.durak@xxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Tested-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.10.x
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/time/timer_list.c | 41 +++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 17 deletions(-)
diff -puN kernel/time/timer_list.c~timer_list-correct-the-iterator-for-timer_list kernel/time/timer_list.c
--- a/kernel/time/timer_list.c~timer_list-correct-the-iterator-for-timer_list
+++ a/kernel/time/timer_list.c
@@ -265,10 +265,9 @@ static inline void timer_list_header(str
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
@@ -298,33 +297,41 @@ 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;
- iter->second_pass = true;
- } else
- return NULL;
+ if (!iter->second_pass) {
+ iter->cpu = -1;
+ iter->second_pass = true;
+ } else
+ return NULL;
#else
- return NULL;
+ 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)
_
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