From patchwork Tue Feb 7 23:40:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 9561519 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2DEF46047A for ; Tue, 7 Feb 2017 23:40:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 229C028467 for ; Tue, 7 Feb 2017 23:40:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 16C9428487; Tue, 7 Feb 2017 23:40:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 9CC7828467 for ; Tue, 7 Feb 2017 23:40:48 +0000 (UTC) Received: (qmail 30139 invoked by uid 550); 7 Feb 2017 23:40:46 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 30110 invoked from network); 7 Feb 2017 23:40:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=QXDP3Kw5M7KQf+J6/WZFXeRMfkbgn2wiVm3YGJHUCYU=; b=TSHqJoI9v5uROzH4qQ1dxyA0F0palEs/HyGVfHyZQ7WBbd4sRZKL/WVaIUYGgezNfa utgRFN+R1tdcTaXgcTN6K6xC6+58byU5tEeVEalU59n47ehUKUjQnhhKWUayCjCxhT/e qKzemuv7X2045NPfHq4j0xyL2iytjQHPlRjo0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=QXDP3Kw5M7KQf+J6/WZFXeRMfkbgn2wiVm3YGJHUCYU=; b=iiH81c8To9tEMstdoCmPMwqjwQlkcsHIQ9iXTyjF0YwDG20NozP45+iRQYZ2vBmbr/ l0pTX0Tr64GH+FOrZAEC3jtnMH28KBP3c3mMp0O5BHwp8gHDsJHFdphzoYpVluhgS7VY mOhIQkfZGM+1w8qIP5HpAP2tNzKGvZO6ee8tOoe859ugcFR3FOPMMyFlmcuxpw3cSR+q Aq+gIqfpulHAeZ0imqmK6kW3gwdsM5xS2iS0m0EsRAUCj0zEoCWgmemKMiRSaQdjGQGt MLfTlJ57bKJU+tmr+cEEgaKK+QbsLZK166jVM6fhU/bzQf0wEf1jYxEdwsP+5qPDMG3n 1sLw== X-Gm-Message-State: AIkVDXIuhSnUriCklcE3V95YVf7cST4OAa2davjPtH8CQFOLIxvdDBYYsH0PrgXdAgfe+tvR X-Received: by 10.99.94.195 with SMTP id s186mr23546975pgb.197.1486510833368; Tue, 07 Feb 2017 15:40:33 -0800 (PST) Date: Tue, 7 Feb 2017 15:40:31 -0800 From: Kees Cook To: Thomas Gleixner Cc: Xing Gao , Jessica Frazelle , "Eric W. Biederman" , Jonathan Corbet , John Stultz , Tejun Heo , Lai Jiangshan , Petr Mladek , Andrew Morton , Oleg Nesterov , Nicolas Iooss , Nicolas Pitre , Richard Cochran , "Paul E. McKenney" , Michal Marek , Josh Poimboeuf , Dmitry Vyukov , Olof Johansson , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Message-ID: <20170207234031.GA27933@beast> MIME-Version: 1.0 Content-Disposition: inline Subject: [kernel-hardening] [PATCH] time: Remove CONFIG_TIMER_STATS X-Virus-Scanned: ClamAV using ClamSMTP Currently CONFIG_TIMER_STATS exposes process information across namespaces: kernel/time/timer_list.c print_timer(): SEQ_printf(m, ", %s/%d", tmp, timer->start_pid); /proc/timer_list: #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570 Given that the tracer can give the same information, this patch entirely removes CONFIG_TIMER_STATS. Suggested-by: Thomas Gleixner Signed-off-by: Kees Cook Acked-by: John Stultz --- Documentation/timers/timer_stats.txt | 73 ------ include/linux/hrtimer.h | 5 - include/linux/timer.h | 45 ---- kernel/kthread.c | 1 - kernel/time/Makefile | 1 - kernel/time/hrtimer.c | 38 ---- kernel/time/timer.c | 48 +--- kernel/time/timer_list.c | 10 - kernel/time/timer_stats.c | 425 ----------------------------------- kernel/workqueue.c | 2 - lib/Kconfig.debug | 14 -- 11 files changed, 2 insertions(+), 660 deletions(-) delete mode 100644 Documentation/timers/timer_stats.txt delete mode 100644 kernel/time/timer_stats.c diff --git a/Documentation/timers/timer_stats.txt b/Documentation/timers/timer_stats.txt deleted file mode 100644 index de835ee97455..000000000000 --- a/Documentation/timers/timer_stats.txt +++ /dev/null @@ -1,73 +0,0 @@ -timer_stats - timer usage statistics ------------------------------------- - -timer_stats is a debugging facility to make the timer (ab)usage in a Linux -system visible to kernel and userspace developers. If enabled in the config -but not used it has almost zero runtime overhead, and a relatively small -data structure overhead. Even if collection is enabled runtime all the -locking is per-CPU and lookup is hashed. - -timer_stats should be used by kernel and userspace developers to verify that -their code does not make unduly use of timers. This helps to avoid unnecessary -wakeups, which should be avoided to optimize power consumption. - -It can be enabled by CONFIG_TIMER_STATS in the "Kernel hacking" configuration -section. - -timer_stats collects information about the timer events which are fired in a -Linux system over a sample period: - -- the pid of the task(process) which initialized the timer -- the name of the process which initialized the timer -- the function where the timer was initialized -- the callback function which is associated to the timer -- the number of events (callbacks) - -timer_stats adds an entry to /proc: /proc/timer_stats - -This entry is used to control the statistics functionality and to read out the -sampled information. - -The timer_stats functionality is inactive on bootup. - -To activate a sample period issue: -# echo 1 >/proc/timer_stats - -To stop a sample period issue: -# echo 0 >/proc/timer_stats - -The statistics can be retrieved by: -# cat /proc/timer_stats - -While sampling is enabled, each readout from /proc/timer_stats will see -newly updated statistics. Once sampling is disabled, the sampled information -is kept until a new sample period is started. This allows multiple readouts. - -Sample output of /proc/timer_stats: - -Timerstats sample period: 3.888770 s - 12, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick) - 15, 1 swapper hcd_submit_urb (rh_timer_func) - 4, 959 kedac schedule_timeout (process_timeout) - 1, 0 swapper page_writeback_init (wb_timer_fn) - 28, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick) - 22, 2948 IRQ 4 tty_flip_buffer_push (delayed_work_timer_fn) - 3, 3100 bash schedule_timeout (process_timeout) - 1, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) - 1, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) - 1, 1 swapper neigh_table_init_no_netlink (neigh_periodic_timer) - 1, 2292 ip __netdev_watchdog_up (dev_watchdog) - 1, 23 events/1 do_cache_clean (delayed_work_timer_fn) -90 total events, 30.0 events/sec - -The first column is the number of events, the second column the pid, the third -column is the name of the process. The forth column shows the function which -initialized the timer and in parenthesis the callback function which was -executed on expiry. - - Thomas, Ingo - -Added flag to indicate 'deferrable timer' in /proc/timer_stats. A deferrable -timer will appear as follows - 10D, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) - diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index cdab81ba29f8..19c66b89899c 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -104,11 +104,6 @@ struct hrtimer { struct hrtimer_clock_base *base; u8 state; u8 is_rel; -#ifdef CONFIG_TIMER_STATS - int start_pid; - void *start_site; - char start_comm[16]; -#endif }; /** diff --git a/include/linux/timer.h b/include/linux/timer.h index 51d601f192d4..5a209b84fd9e 100644 --- a/include/linux/timer.h +++ b/include/linux/timer.h @@ -20,11 +20,6 @@ struct timer_list { unsigned long data; u32 flags; -#ifdef CONFIG_TIMER_STATS - int start_pid; - void *start_site; - char start_comm[16]; -#endif #ifdef CONFIG_LOCKDEP struct lockdep_map lockdep_map; #endif @@ -197,46 +192,6 @@ extern int mod_timer_pending(struct timer_list *timer, unsigned long expires); */ #define NEXT_TIMER_MAX_DELTA ((1UL << 30) - 1) -/* - * Timer-statistics info: - */ -#ifdef CONFIG_TIMER_STATS - -extern int timer_stats_active; - -extern void init_timer_stats(void); - -extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf, - void *timerf, char *comm, u32 flags); - -extern void __timer_stats_timer_set_start_info(struct timer_list *timer, - void *addr); - -static inline void timer_stats_timer_set_start_info(struct timer_list *timer) -{ - if (likely(!timer_stats_active)) - return; - __timer_stats_timer_set_start_info(timer, __builtin_return_address(0)); -} - -static inline void timer_stats_timer_clear_start_info(struct timer_list *timer) -{ - timer->start_site = NULL; -} -#else -static inline void init_timer_stats(void) -{ -} - -static inline void timer_stats_timer_set_start_info(struct timer_list *timer) -{ -} - -static inline void timer_stats_timer_clear_start_info(struct timer_list *timer) -{ -} -#endif - extern void add_timer(struct timer_list *timer); extern int try_to_del_timer_sync(struct timer_list *timer); diff --git a/kernel/kthread.c b/kernel/kthread.c index 2318fba86277..8461a4372e8a 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -850,7 +850,6 @@ void __kthread_queue_delayed_work(struct kthread_worker *worker, list_add(&work->node, &worker->delayed_work_list); work->worker = worker; - timer_stats_timer_set_start_info(&dwork->timer); timer->expires = jiffies + delay; add_timer(timer); } diff --git a/kernel/time/Makefile b/kernel/time/Makefile index 976840d29a71..938dbf33ef49 100644 --- a/kernel/time/Makefile +++ b/kernel/time/Makefile @@ -15,6 +15,5 @@ ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y) endif obj-$(CONFIG_GENERIC_SCHED_CLOCK) += sched_clock.o obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o tick-sched.o -obj-$(CONFIG_TIMER_STATS) += timer_stats.o obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o obj-$(CONFIG_TEST_UDELAY) += test_udelay.o diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index c6ecedd3b839..edabde646e58 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -766,34 +766,6 @@ void hrtimers_resume(void) clock_was_set_delayed(); } -static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer) -{ -#ifdef CONFIG_TIMER_STATS - if (timer->start_site) - return; - timer->start_site = __builtin_return_address(0); - memcpy(timer->start_comm, current->comm, TASK_COMM_LEN); - timer->start_pid = current->pid; -#endif -} - -static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer) -{ -#ifdef CONFIG_TIMER_STATS - timer->start_site = NULL; -#endif -} - -static inline void timer_stats_account_hrtimer(struct hrtimer *timer) -{ -#ifdef CONFIG_TIMER_STATS - if (likely(!timer_stats_active)) - return; - timer_stats_update_stats(timer, timer->start_pid, timer->start_site, - timer->function, timer->start_comm, 0); -#endif -} - /* * Counterpart to lock_hrtimer_base above: */ @@ -932,7 +904,6 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool rest * rare case and less expensive than a smp call. */ debug_deactivate(timer); - timer_stats_hrtimer_clear_start_info(timer); reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases); if (!restart) @@ -990,8 +961,6 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim, /* Switch the timer base, if necessary: */ new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED); - timer_stats_hrtimer_set_start_info(timer); - leftmost = enqueue_hrtimer(timer, new_base); if (!leftmost) goto unlock; @@ -1128,12 +1097,6 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id, base = hrtimer_clockid_to_base(clock_id); timer->base = &cpu_base->clock_base[base]; timerqueue_init(&timer->node); - -#ifdef CONFIG_TIMER_STATS - timer->start_site = NULL; - timer->start_pid = -1; - memset(timer->start_comm, 0, TASK_COMM_LEN); -#endif } /** @@ -1217,7 +1180,6 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, raw_write_seqcount_barrier(&cpu_base->seq); __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0); - timer_stats_account_hrtimer(timer); fn = timer->function; /* diff --git a/kernel/time/timer.c b/kernel/time/timer.c index ec33a6933eae..82a6bfa0c307 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -571,38 +571,6 @@ internal_add_timer(struct timer_base *base, struct timer_list *timer) trigger_dyntick_cpu(base, timer); } -#ifdef CONFIG_TIMER_STATS -void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr) -{ - if (timer->start_site) - return; - - timer->start_site = addr; - memcpy(timer->start_comm, current->comm, TASK_COMM_LEN); - timer->start_pid = current->pid; -} - -static void timer_stats_account_timer(struct timer_list *timer) -{ - void *site; - - /* - * start_site can be concurrently reset by - * timer_stats_timer_clear_start_info() - */ - site = READ_ONCE(timer->start_site); - if (likely(!site)) - return; - - timer_stats_update_stats(timer, timer->start_pid, site, - timer->function, timer->start_comm, - timer->flags); -} - -#else -static void timer_stats_account_timer(struct timer_list *timer) {} -#endif - #ifdef CONFIG_DEBUG_OBJECTS_TIMERS static struct debug_obj_descr timer_debug_descr; @@ -789,11 +757,6 @@ static void do_init_timer(struct timer_list *timer, unsigned int flags, { timer->entry.pprev = NULL; timer->flags = flags | raw_smp_processor_id(); -#ifdef CONFIG_TIMER_STATS - timer->start_site = NULL; - timer->start_pid = -1; - memset(timer->start_comm, 0, TASK_COMM_LEN); -#endif lockdep_init_map(&timer->lockdep_map, name, key, 0); } @@ -1001,8 +964,6 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) base = lock_timer_base(timer, &flags); } - timer_stats_timer_set_start_info(timer); - ret = detach_if_pending(timer, base, false); if (!ret && pending_only) goto out_unlock; @@ -1130,7 +1091,6 @@ void add_timer_on(struct timer_list *timer, int cpu) struct timer_base *new_base, *base; unsigned long flags; - timer_stats_timer_set_start_info(timer); BUG_ON(timer_pending(timer) || !timer->function); new_base = get_timer_cpu_base(timer->flags, cpu); @@ -1176,7 +1136,6 @@ int del_timer(struct timer_list *timer) debug_assert_init(timer); - timer_stats_timer_clear_start_info(timer); if (timer_pending(timer)) { base = lock_timer_base(timer, &flags); ret = detach_if_pending(timer, base, true); @@ -1204,10 +1163,9 @@ int try_to_del_timer_sync(struct timer_list *timer) base = lock_timer_base(timer, &flags); - if (base->running_timer != timer) { - timer_stats_timer_clear_start_info(timer); + if (base->running_timer != timer) ret = detach_if_pending(timer, base, true); - } + spin_unlock_irqrestore(&base->lock, flags); return ret; @@ -1331,7 +1289,6 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head) unsigned long data; timer = hlist_entry(head->first, struct timer_list, entry); - timer_stats_account_timer(timer); base->running_timer = timer; detach_timer(timer, true); @@ -1868,7 +1825,6 @@ static void __init init_timer_cpus(void) void __init init_timers(void) { init_timer_cpus(); - init_timer_stats(); open_softirq(TIMER_SOFTIRQ, run_timer_softirq); } diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c index afe6cd1944fc..387a3a5aa388 100644 --- a/kernel/time/timer_list.c +++ b/kernel/time/timer_list.c @@ -62,21 +62,11 @@ static void print_timer(struct seq_file *m, struct hrtimer *taddr, struct hrtimer *timer, int idx, u64 now) { -#ifdef CONFIG_TIMER_STATS - char tmp[TASK_COMM_LEN + 1]; -#endif SEQ_printf(m, " #%d: ", idx); print_name_offset(m, taddr); SEQ_printf(m, ", "); print_name_offset(m, timer->function); SEQ_printf(m, ", S:%02x", timer->state); -#ifdef CONFIG_TIMER_STATS - SEQ_printf(m, ", "); - print_name_offset(m, timer->start_site); - memcpy(tmp, timer->start_comm, TASK_COMM_LEN); - tmp[TASK_COMM_LEN] = 0; - SEQ_printf(m, ", %s/%d", tmp, timer->start_pid); -#endif SEQ_printf(m, "\n"); SEQ_printf(m, " # expires at %Lu-%Lu nsecs [in %Ld to %Ld nsecs]\n", (unsigned long long)ktime_to_ns(hrtimer_get_softexpires(timer)), diff --git a/kernel/time/timer_stats.c b/kernel/time/timer_stats.c deleted file mode 100644 index afddded947df..000000000000 --- a/kernel/time/timer_stats.c +++ /dev/null @@ -1,425 +0,0 @@ -/* - * kernel/time/timer_stats.c - * - * Collect timer usage statistics. - * - * Copyright(C) 2006, Red Hat, Inc., Ingo Molnar - * Copyright(C) 2006 Timesys Corp., Thomas Gleixner - * - * timer_stats is based on timer_top, a similar functionality which was part of - * Con Kolivas dyntick patch set. It was developed by Daniel Petrini at the - * Instituto Nokia de Tecnologia - INdT - Manaus. timer_top's design was based - * on dynamic allocation of the statistics entries and linear search based - * lookup combined with a global lock, rather than the static array, hash - * and per-CPU locking which is used by timer_stats. It was written for the - * pre hrtimer kernel code and therefore did not take hrtimers into account. - * Nevertheless it provided the base for the timer_stats implementation and - * was a helpful source of inspiration. Kudos to Daniel and the Nokia folks - * for this effort. - * - * timer_top.c is - * Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus - * Written by Daniel Petrini - * timer_top.c was released under the GNU General Public License version 2 - * - * We export the addresses and counting of timer functions being called, - * the pid and cmdline from the owner process if applicable. - * - * Start/stop data collection: - * # echo [1|0] >/proc/timer_stats - * - * Display the information collected so far: - * # cat /proc/timer_stats - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License version 2 as - * published by the Free Software Foundation. - */ - -#include -#include -#include -#include -#include -#include - -#include - -/* - * This is our basic unit of interest: a timer expiry event identified - * by the timer, its start/expire functions and the PID of the task that - * started the timer. We count the number of times an event happens: - */ -struct entry { - /* - * Hash list: - */ - struct entry *next; - - /* - * Hash keys: - */ - void *timer; - void *start_func; - void *expire_func; - pid_t pid; - - /* - * Number of timeout events: - */ - unsigned long count; - u32 flags; - - /* - * We save the command-line string to preserve - * this information past task exit: - */ - char comm[TASK_COMM_LEN + 1]; - -} ____cacheline_aligned_in_smp; - -/* - * Spinlock protecting the tables - not taken during lookup: - */ -static DEFINE_RAW_SPINLOCK(table_lock); - -/* - * Per-CPU lookup locks for fast hash lookup: - */ -static DEFINE_PER_CPU(raw_spinlock_t, tstats_lookup_lock); - -/* - * Mutex to serialize state changes with show-stats activities: - */ -static DEFINE_MUTEX(show_mutex); - -/* - * Collection status, active/inactive: - */ -int __read_mostly timer_stats_active; - -/* - * Beginning/end timestamps of measurement: - */ -static ktime_t time_start, time_stop; - -/* - * tstat entry structs only get allocated while collection is - * active and never freed during that time - this simplifies - * things quite a bit. - * - * They get freed when a new collection period is started. - */ -#define MAX_ENTRIES_BITS 10 -#define MAX_ENTRIES (1UL << MAX_ENTRIES_BITS) - -static unsigned long nr_entries; -static struct entry entries[MAX_ENTRIES]; - -static atomic_t overflow_count; - -/* - * The entries are in a hash-table, for fast lookup: - */ -#define TSTAT_HASH_BITS (MAX_ENTRIES_BITS - 1) -#define TSTAT_HASH_SIZE (1UL << TSTAT_HASH_BITS) -#define TSTAT_HASH_MASK (TSTAT_HASH_SIZE - 1) - -#define __tstat_hashfn(entry) \ - (((unsigned long)(entry)->timer ^ \ - (unsigned long)(entry)->start_func ^ \ - (unsigned long)(entry)->expire_func ^ \ - (unsigned long)(entry)->pid ) & TSTAT_HASH_MASK) - -#define tstat_hashentry(entry) (tstat_hash_table + __tstat_hashfn(entry)) - -static struct entry *tstat_hash_table[TSTAT_HASH_SIZE] __read_mostly; - -static void reset_entries(void) -{ - nr_entries = 0; - memset(entries, 0, sizeof(entries)); - memset(tstat_hash_table, 0, sizeof(tstat_hash_table)); - atomic_set(&overflow_count, 0); -} - -static struct entry *alloc_entry(void) -{ - if (nr_entries >= MAX_ENTRIES) - return NULL; - - return entries + nr_entries++; -} - -static int match_entries(struct entry *entry1, struct entry *entry2) -{ - return entry1->timer == entry2->timer && - entry1->start_func == entry2->start_func && - entry1->expire_func == entry2->expire_func && - entry1->pid == entry2->pid; -} - -/* - * Look up whether an entry matching this item is present - * in the hash already. Must be called with irqs off and the - * lookup lock held: - */ -static struct entry *tstat_lookup(struct entry *entry, char *comm) -{ - struct entry **head, *curr, *prev; - - head = tstat_hashentry(entry); - curr = *head; - - /* - * The fastpath is when the entry is already hashed, - * we do this with the lookup lock held, but with the - * table lock not held: - */ - while (curr) { - if (match_entries(curr, entry)) - return curr; - - curr = curr->next; - } - /* - * Slowpath: allocate, set up and link a new hash entry: - */ - prev = NULL; - curr = *head; - - raw_spin_lock(&table_lock); - /* - * Make sure we have not raced with another CPU: - */ - while (curr) { - if (match_entries(curr, entry)) - goto out_unlock; - - prev = curr; - curr = curr->next; - } - - curr = alloc_entry(); - if (curr) { - *curr = *entry; - curr->count = 0; - curr->next = NULL; - memcpy(curr->comm, comm, TASK_COMM_LEN); - - smp_mb(); /* Ensure that curr is initialized before insert */ - - if (prev) - prev->next = curr; - else - *head = curr; - } - out_unlock: - raw_spin_unlock(&table_lock); - - return curr; -} - -/** - * timer_stats_update_stats - Update the statistics for a timer. - * @timer: pointer to either a timer_list or a hrtimer - * @pid: the pid of the task which set up the timer - * @startf: pointer to the function which did the timer setup - * @timerf: pointer to the timer callback function of the timer - * @comm: name of the process which set up the timer - * @tflags: The flags field of the timer - * - * When the timer is already registered, then the event counter is - * incremented. Otherwise the timer is registered in a free slot. - */ -void timer_stats_update_stats(void *timer, pid_t pid, void *startf, - void *timerf, char *comm, u32 tflags) -{ - /* - * It doesn't matter which lock we take: - */ - raw_spinlock_t *lock; - struct entry *entry, input; - unsigned long flags; - - if (likely(!timer_stats_active)) - return; - - lock = &per_cpu(tstats_lookup_lock, raw_smp_processor_id()); - - input.timer = timer; - input.start_func = startf; - input.expire_func = timerf; - input.pid = pid; - input.flags = tflags; - - raw_spin_lock_irqsave(lock, flags); - if (!timer_stats_active) - goto out_unlock; - - entry = tstat_lookup(&input, comm); - if (likely(entry)) - entry->count++; - else - atomic_inc(&overflow_count); - - out_unlock: - raw_spin_unlock_irqrestore(lock, flags); -} - -static void print_name_offset(struct seq_file *m, unsigned long addr) -{ - char symname[KSYM_NAME_LEN]; - - if (lookup_symbol_name(addr, symname) < 0) - seq_printf(m, "<%p>", (void *)addr); - else - seq_printf(m, "%s", symname); -} - -static int tstats_show(struct seq_file *m, void *v) -{ - struct timespec64 period; - struct entry *entry; - unsigned long ms; - long events = 0; - ktime_t time; - int i; - - mutex_lock(&show_mutex); - /* - * If still active then calculate up to now: - */ - if (timer_stats_active) - time_stop = ktime_get(); - - time = ktime_sub(time_stop, time_start); - - period = ktime_to_timespec64(time); - ms = period.tv_nsec / 1000000; - - seq_puts(m, "Timer Stats Version: v0.3\n"); - seq_printf(m, "Sample period: %ld.%03ld s\n", (long)period.tv_sec, ms); - if (atomic_read(&overflow_count)) - seq_printf(m, "Overflow: %d entries\n", atomic_read(&overflow_count)); - seq_printf(m, "Collection: %s\n", timer_stats_active ? "active" : "inactive"); - - for (i = 0; i < nr_entries; i++) { - entry = entries + i; - if (entry->flags & TIMER_DEFERRABLE) { - seq_printf(m, "%4luD, %5d %-16s ", - entry->count, entry->pid, entry->comm); - } else { - seq_printf(m, " %4lu, %5d %-16s ", - entry->count, entry->pid, entry->comm); - } - - print_name_offset(m, (unsigned long)entry->start_func); - seq_puts(m, " ("); - print_name_offset(m, (unsigned long)entry->expire_func); - seq_puts(m, ")\n"); - - events += entry->count; - } - - ms += period.tv_sec * 1000; - if (!ms) - ms = 1; - - if (events && period.tv_sec) - seq_printf(m, "%ld total events, %ld.%03ld events/sec\n", - events, events * 1000 / ms, - (events * 1000000 / ms) % 1000); - else - seq_printf(m, "%ld total events\n", events); - - mutex_unlock(&show_mutex); - - return 0; -} - -/* - * After a state change, make sure all concurrent lookup/update - * activities have stopped: - */ -static void sync_access(void) -{ - unsigned long flags; - int cpu; - - for_each_online_cpu(cpu) { - raw_spinlock_t *lock = &per_cpu(tstats_lookup_lock, cpu); - - raw_spin_lock_irqsave(lock, flags); - /* nothing */ - raw_spin_unlock_irqrestore(lock, flags); - } -} - -static ssize_t tstats_write(struct file *file, const char __user *buf, - size_t count, loff_t *offs) -{ - char ctl[2]; - - if (count != 2 || *offs) - return -EINVAL; - - if (copy_from_user(ctl, buf, count)) - return -EFAULT; - - mutex_lock(&show_mutex); - switch (ctl[0]) { - case '0': - if (timer_stats_active) { - timer_stats_active = 0; - time_stop = ktime_get(); - sync_access(); - } - break; - case '1': - if (!timer_stats_active) { - reset_entries(); - time_start = ktime_get(); - smp_mb(); - timer_stats_active = 1; - } - break; - default: - count = -EINVAL; - } - mutex_unlock(&show_mutex); - - return count; -} - -static int tstats_open(struct inode *inode, struct file *filp) -{ - return single_open(filp, tstats_show, NULL); -} - -static const struct file_operations tstats_fops = { - .open = tstats_open, - .read = seq_read, - .write = tstats_write, - .llseek = seq_lseek, - .release = single_release, -}; - -void __init init_timer_stats(void) -{ - int cpu; - - for_each_possible_cpu(cpu) - raw_spin_lock_init(&per_cpu(tstats_lookup_lock, cpu)); -} - -static int __init init_tstats_procfs(void) -{ - struct proc_dir_entry *pe; - - pe = proc_create("timer_stats", 0644, NULL, &tstats_fops); - if (!pe) - return -ENOMEM; - return 0; -} -__initcall(init_tstats_procfs); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 1d9fb6543a66..072cbc9b175d 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1523,8 +1523,6 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, return; } - timer_stats_timer_set_start_info(&dwork->timer); - dwork->wq = wq; dwork->cpu = cpu; timer->expires = jiffies + delay; diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index eb9e9a7870fa..132af338d6dd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -980,20 +980,6 @@ config DEBUG_TIMEKEEPING If unsure, say N. -config TIMER_STATS - bool "Collect kernel timers statistics" - depends on DEBUG_KERNEL && PROC_FS - help - If you say Y here, additional code will be inserted into the - timer routines to collect statistics about kernel timers being - reprogrammed. The statistics can be read from /proc/timer_stats. - The statistics collection is started by writing 1 to /proc/timer_stats, - writing 0 stops it. This feature is useful to collect information - about timer usage patterns in kernel and userspace. This feature - is lightweight if enabled in the kernel config but not activated - (it defaults to deactivated on bootup and will only be activated - if some application like powertop activates it explicitly). - config DEBUG_PREEMPT bool "Debug preemptible kernel" depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT