[RFC] watchdog: Adding softwatchdog

Message ID	20210424102555.28203-2-peter.enderborg@sony.com
State	New
Headers	show Return-Path: <linux-watchdog-owner@kernel.org> From: Peter Enderborg <peter.enderborg@sony.com> To: Wim Van Sebroeck <wim@linux-watchdog.org>, Guenter Roeck <linux@roeck-us.net>, Andrew Morton <akpm@linux-foundation.org>, <linux-watchdog@vger.kernel.org>, <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>, Shakeel Butt <shakeelb@google.com> CC: Peter Enderborg <peter.enderborg@sony.com> Subject: [RFC PATCH] watchdog: Adding softwatchdog Date: Sat, 24 Apr 2021 12:25:55 +0200 Message-ID: <20210424102555.28203-2-peter.enderborg@sony.com> In-Reply-To: <20210424102555.28203-1-peter.enderborg@sony.com> References: <20210424102555.28203-1-peter.enderborg@sony.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk
Series	[RFC] watchdog: Adding softwatchdog \| expand [RFC] watchdog: Adding softwatchdog

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index f3a6540e725e..bff8f61fe504 100644 --- a/drivers/watchdog/Makefile +++ b/drivers/watchdog/Makefile @@ -221,3 +221,5 @@ obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o obj-$(CONFIG_SL28CPLD_WATCHDOG) += sl28cpld_wdt.o + +obj-y += softwatchdog.o diff --git a/drivers/watchdog/softwatchdog.c b/drivers/watchdog/softwatchdog.c new file mode 100644 index 000000000000..dd7153092da8 --- /dev/null +++ b/drivers/watchdog/softwatchdog.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Soft watchdog + * This is a RFC of a watchdog does do not reboot the system. + * Instead it do a pre defined action + * + * Author: peter.enderborg@sony.com + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/oom.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/types.h> +#include <linux/timer.h> +#include <linux/miscdevice.h> +#include <linux/watchdog.h> +#include <linux/notifier.h> +#include <linux/init.h> +#include <linux/fs.h> + +void wake_oom_reaper(struct task_struct *tsk); /* need to public ... */ +void __oom_kill_process(struct task_struct *victim, const char *message); /* hmm */ + +static struct timer_list swd_timer; +static int heartbeat = 500; +static unsigned long swd_is_open; +static char expect_close; +static bool nowayout = WATCHDOG_NOWAYOUT; + +/* a example policy doing a process kill by calling + * functions within oom-killer. + */ +static int policy_fast_kill_oom_score_adj(void) +{ + struct task_struct *tsk; + struct task_struct *selected = NULL; + int highest = 0; + + rcu_read_lock(); + for_each_process(tsk) { + struct task_struct *candidate; + + if (tsk->flags & PF_KTHREAD) + continue; + + /* Ignore task if coredump in progress */ + if (tsk->mm && tsk->mm->core_state) + continue; + candidate = find_lock_task_mm(tsk); + if (!candidate) + continue; + + if (highest < candidate->signal->oom_score_adj) { + /* for test dont kill level 0 */ + highest = candidate->signal->oom_score_adj; + selected = candidate; + pr_info("new selected %d %d", selected->pid, + selected->signal->oom_score_adj); + } + task_unlock(candidate); + } + if (selected) + get_task_struct(selected); + + rcu_read_unlock(); + if (selected) { + int pid = selected->pid; + + pr_info("swd killing: %d", selected->pid); + __oom_kill_process(selected, "swd"); + return pid; + } + return 0; +} + +static void swd_ping(void) +{ + mod_timer(&swd_timer, jiffies + heartbeat); +} + +static long swd_ioctl(struct file *file, unsigned int cmd, unsigned long arg) +{ + void __user *argp = (void __user *)arg; + int __user *p = argp; + int new_heartbeat; + int status; + + struct watchdog_info ident = { + .options = WDIOF_SETTIMEOUT| + WDIOF_MAGICCLOSE| + WDIOF_OOMKILL | + WDIOF_AUTOKILL, + .identity = "swd", + }; + + switch (cmd) { + case WDIOC_GETSUPPORT: + return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; + case WDIOC_GETSTATUS: + status = 0; + return put_user(status, p); + case WDIOC_GETBOOTSTATUS: + return put_user(0, p); + case WDIOC_KEEPALIVE: + swd_ping(); + return 0; + case WDIOC_SETTIMEOUT: + if (get_user(new_heartbeat, p)) + return -EFAULT; + heartbeat = new_heartbeat; + fallthrough; + case WDIOC_GETTIMEOUT: + return put_user(heartbeat, p); + default: + return -ENOTTY; + } + return -ENOTTY; +} + +static void swd_timer_func(struct timer_list *unused) +{ + int res; + + pr_info("swd timer %d\n", heartbeat); + res = policy_fast_kill_oom_score_adj(); + if (res) + pr_info("killed %d\n", res); + + mod_timer(&swd_timer, jiffies + heartbeat); +} + +static int swd_start(void) +{ + add_timer(&swd_timer); + return 0; +} + +static int swd_stop(void) +{ + del_timer(&swd_timer); + return 0; +} + +static int swd_open(struct inode *inode, struct file *file) +{ + if (test_and_set_bit(0, &swd_is_open)) + return -EBUSY; + swd_start(); + return stream_open(inode, file); +} + +static int swd_release(struct inode *inode, struct file *file) +{ + if (expect_close != 42) { + swd_stop(); + clear_bit(0, &swd_is_open); + } else { + pr_crit("SWD device closed unexpectedly. SWD will not stop!\n"); + swd_ping(); + } + expect_close = 0; + return 0; +} +static ssize_t swd_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + if (count) { + if (!nowayout) { + size_t i; + + expect_close = 0; + for (i = 0; i != count; i++) { + char c; + + if (get_user(c, buf + i)) + return -EFAULT; + if (c == 'V') + expect_close = 42; + } + } + swd_ping(); + } + return count; +} + +static const struct file_operations swd_fops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .write = swd_write, + .unlocked_ioctl = swd_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .open = swd_open, + .release = swd_release, +}; + +static struct miscdevice swd_miscdev = { + .minor = WATCHDOG_MINOR, + .name = "soft-watchdog", + .fops = &swd_fops, +}; + +int __init swd_register(void) +{ + int ret; + + pr_info("swd installed with timer"); + ret = misc_register(&swd_miscdev); + timer_setup(&swd_timer, swd_timer_func, 0); + return 0; +} + +static int __init swd_init(void) +{ + return 0; +} + +static void __exit swd_unload(void) +{ + return; +} + +subsys_initcall(swd_register); + +module_init(swd_init); +module_exit(swd_unload); + +MODULE_AUTHOR("Peter Enderborg"); +MODULE_DESCRIPTION("Memory software watchdog"); +MODULE_LICENSE("GPL"); diff --git a/include/uapi/linux/watchdog.h b/include/uapi/linux/watchdog.h index b15cde5c9054..780987482e2d 100644 --- a/include/uapi/linux/watchdog.h +++ b/include/uapi/linux/watchdog.h @@ -48,6 +48,12 @@ struct watchdog_info { #define WDIOF_PRETIMEOUT 0x0200 /* Pretimeout (in seconds), get/set */ #define WDIOF_ALARMONLY 0x0400 /* Watchdog triggers a management or other external alarm not a reboot */ +#define WDIOF_OOMKILL 0x0800 /* Watchdog trigger process kill as + * oom kill + */ +#define WDIOF_AUTOKILL 0x1000 /* Watchdog listen to oom notifiy + * and kills with its policy + */ #define WDIOF_KEEPALIVEPING 0x8000 /* Keep alive ping reply */ #define WDIOS_DISABLECARD 0x0001 /* Turn off the watchdog timer */ diff --git a/mm/oom_kill.c b/mm/oom_kill.c index fa1cf18bac97..a5f7299af9a3 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -658,7 +658,7 @@ static int oom_reaper(void *unused) return 0; } -static void wake_oom_reaper(struct task_struct *tsk) +void wake_oom_reaper(struct task_struct *tsk) { /* mm is already queued? */ if (test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags)) @@ -856,7 +856,7 @@ static bool task_will_free_mem(struct task_struct *task) return ret; } -static void __oom_kill_process(struct task_struct *victim, const char *message) +void __oom_kill_process(struct task_struct *victim, const char *message) { struct task_struct *p; struct mm_struct *mm;

[RFC] watchdog: Adding softwatchdog

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