From b3956a896ea57f25cacd74708b8fab611543a81d Mon Sep 17 00:00:00 2001 From: Nathan Zimmer Date: Tue, 26 Mar 2013 19:56:30 -0500 Subject: [PATCH] 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 Reported-by: Dave Jones Cc: John Stultz Cc: Stephen Boyd Link: http://lkml.kernel.org/r/1364345790-14577-3-git-send-email-nzimmer@sgi.com Signed-off-by: Thomas Gleixner --- 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 + +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) -- 2.7.4