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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@sgi.com>
Reported-by: Dave Jones <davej@redhat.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Link: http://lkml.kernel.org/r/1364345790-14577-3-git-send-email-nzimmer@sgi.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Nathan Zimmer 2013-03-26 19:56:30 -05:00 committed by Thomas Gleixner
parent 60cf7ea849
commit b3956a896e
1 changed files with 78 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

91
kernel/time/timer_list.c
View File

@ -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");
}
for_each_online_cpu(cpu)
print_cpu(m, cpu, 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);
else if (!iter->second_pass)
print_cpu(m, iter->cpu, iter->now);
#ifdef CONFIG_GENERIC_CLOCKEVENTS
timer_list_show_tickdevices_header(m);
for_each_online_cpu(cpu)
print_tickdevice(m, tick_get_device(cpu), cpu);
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)
{
timer_list_show(NULL, NULL);
u64 now = ktime_to_ns(ktime_get());
int cpu;
timer_list_header(NULL, now);
for_each_online_cpu(cpu)
print_cpu(NULL, cpu, now);
#ifdef CONFIG_GENERIC_CLOCKEVENTS
timer_list_show_tickdevices_header(NULL);
for_each_online_cpu(cpu)
print_tickdevice(NULL, tick_get_device(cpu), cpu);
#endif
return;
}
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;
}
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);
}
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)