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Date: Tue, 26 Mar 2013 19:56:30 -0500
From: Nathan Zimmer <nzimmer@....com>
To: unlisted-recipients:; (no To-header on input)
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
Nathan Zimmer <nzimmer@....com>,
John Stultz <johnstul@...ibm.com>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...eaurora.org>
Subject: [PATCH 2/2] timer_list: convert timer list to be a proper seq_file
When running with 4096 cores attemping to read /proc/timer_list will fail
with an ENOMEM condition. On a sufficantly large systems the total amount
of data is more then 4mb, so it won't fit into a single buffer. The
failure can also occur on smaller systems when memory fragmentation is
high as reported by Dave Jones.
Convert /proc/timer_list to a proper seq_file with its own iterator. This
is a little more complex given that we have to make two passes with two
separate headers.
sysrq_timer_list_show also needed to be updated to reflect the fact that
now timer_list_show only does one cpu at at time.
Signed-off-by: Nathan Zimmer <nzimmer@....com>
Reported-by: Dave Jones <davej@...hat.com>
Cc: John Stultz <johnstul@...ibm.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Stephen Boyd <sboyd@...eaurora.org>
v2: Added comments on the iteration and other fixups pointed to by Andrew.
v3: Corrected the case where max_cpus != nr_cpu_ids by exiting early.
v5: Use seq_open_private and supply a proper iterator rather then a big mess.
---
kernel/time/timer_list.c | 89 +++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 77 insertions(+), 12 deletions(-)
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 380a589..3bdf283 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -20,6 +20,13 @@
#include <asm/uaccess.h>
+
+struct timer_list_iter {
+ int cpu;
+ bool second_pass;
+ u64 now;
+};
+
typedef void (*print_fn_t)(struct seq_file *m, unsigned int *classes);
DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases);
@@ -247,43 +254,101 @@ static void timer_list_show_tickdevices_header(struct seq_file *m)
}
#endif
-static int timer_list_show(struct seq_file *m, void *v)
+static inline void timer_list_header(struct seq_file *m, u64 now)
{
- u64 now = ktime_to_ns(ktime_get());
- int cpu;
-
SEQ_printf(m, "Timer List Version: v0.7\n");
SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);
SEQ_printf(m, "\n");
+}
+
+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);
+ else if (!iter->second_pass)
+ print_cpu(m, iter->cpu, iter->now);
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ else if (iter->cpu == -1 && iter->second_pass)
+ timer_list_show_tickdevices_header(m);
+ else
+ print_tickdevice(m, tick_get_device(iter->cpu), iter->cpu);
+#endif
+ return 0;
+}
+
+void sysrq_timer_list_show(void)
+{
+ u64 now = ktime_to_ns(ktime_get());
+ int cpu;
+
+ timer_list_header(NULL, now);
for_each_online_cpu(cpu)
- print_cpu(m, cpu, now);
+ print_cpu(NULL, cpu, now);
#ifdef CONFIG_GENERIC_CLOCKEVENTS
- timer_list_show_tickdevices_header(m);
+ timer_list_show_tickdevices_header(NULL);
for_each_online_cpu(cpu)
- print_tickdevice(m, tick_get_device(cpu), cpu);
+ print_tickdevice(NULL, tick_get_device(cpu), cpu);
#endif
+ return;
+}
- return 0;
+static void *timer_list_start(struct seq_file *file, 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) {
+#ifdef CONFIG_GENERIC_CLOCKEVENTS
+ if (!iter->second_pass) {
+ iter->cpu = -1;
+ iter->second_pass = true;
+ } else
+ return NULL;
+#else
+ return NULL;
+#endif
+ }
+ return iter;
}
-void sysrq_timer_list_show(void)
+static void *timer_list_next(struct seq_file *file, void *v, loff_t *offset)
{
- timer_list_show(NULL, NULL);
+ struct timer_list_iter *iter = file->private;
+ iter->cpu = cpumask_next(iter->cpu, cpu_online_mask);
+ ++*offset;
+ return timer_list_start(file, offset);
}
+static void timer_list_stop(struct seq_file *seq, void *v)
+{
+}
+
+static const struct seq_operations timer_list_sops = {
+ .start = timer_list_start,
+ .next = timer_list_next,
+ .stop = timer_list_stop,
+ .show = timer_list_show,
+};
+
static int timer_list_open(struct inode *inode, struct file *filp)
{
- return single_open(filp, timer_list_show, NULL);
+ return seq_open_private(filp, &timer_list_sops,
+ sizeof(struct timer_list_iter));
}
static const struct file_operations timer_list_fops = {
.open = timer_list_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = single_release,
+ .release = seq_release_private,
};
static int __init init_timer_list_procfs(void)
--
1.8.1.2
--
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