/* * drivers/char/watchdog/ixp4xx_wdt.c * * Watchdog driver for Intel IXP4xx network processors * * Author: Deepak Saxena * * Copyright 2004 (c) MontaVista, Software, Inc. * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include #include static bool nowayout = WATCHDOG_NOWAYOUT; static int heartbeat = 60; /* (secs) Default is 1 minute */ static unsigned long wdt_status; static unsigned long boot_status; static DEFINE_SPINLOCK(wdt_lock); #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL) #define WDT_IN_USE 0 #define WDT_OK_TO_CLOSE 1 static void wdt_enable(void) { spin_lock(&wdt_lock); *IXP4XX_OSWK = IXP4XX_WDT_KEY; *IXP4XX_OSWE = 0; *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat; *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE; *IXP4XX_OSWK = 0; spin_unlock(&wdt_lock); } static void wdt_disable(void) { spin_lock(&wdt_lock); *IXP4XX_OSWK = IXP4XX_WDT_KEY; *IXP4XX_OSWE = 0; *IXP4XX_OSWK = 0; spin_unlock(&wdt_lock); } static int ixp4xx_wdt_open(struct inode *inode, struct file *file) { if (test_and_set_bit(WDT_IN_USE, &wdt_status)) return -EBUSY; clear_bit(WDT_OK_TO_CLOSE, &wdt_status); wdt_enable(); return nonseekable_open(inode, file); } static ssize_t ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos) { if (len) { if (!nowayout) { size_t i; clear_bit(WDT_OK_TO_CLOSE, &wdt_status); for (i = 0; i != len; i++) { char c; if (get_user(c, data + i)) return -EFAULT; if (c == 'V') set_bit(WDT_OK_TO_CLOSE, &wdt_status); } } wdt_enable(); } return len; } static const struct watchdog_info ident = { .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, .identity = "IXP4xx Watchdog", }; static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { int ret = -ENOTTY; int time; switch (cmd) { case WDIOC_GETSUPPORT: ret = copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)) ? -EFAULT : 0; break; case WDIOC_GETSTATUS: ret = put_user(0, (int *)arg); break; case WDIOC_GETBOOTSTATUS: ret = put_user(boot_status, (int *)arg); break; case WDIOC_KEEPALIVE: wdt_enable(); ret = 0; break; case WDIOC_SETTIMEOUT: ret = get_user(time, (int *)arg); if (ret) break; if (time <= 0 || time > 60) { ret = -EINVAL; break; } heartbeat = time; wdt_enable(); /* Fall through */ case WDIOC_GETTIMEOUT: ret = put_user(heartbeat, (int *)arg); break; } return ret; } static int ixp4xx_wdt_release(struct inode *inode, struct file *file) { if (test_bit(WDT_OK_TO_CLOSE, &wdt_status)) wdt_disable(); else pr_crit("Device closed unexpectedly - timer will not stop\n"); clear_bit(WDT_IN_USE, &wdt_status); clear_bit(WDT_OK_TO_CLOSE, &wdt_status); return 0; } static const struct file_operations ixp4xx_wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = ixp4xx_wdt_write, .unlocked_ioctl = ixp4xx_wdt_ioctl, .open = ixp4xx_wdt_open, .release = ixp4xx_wdt_release, }; static struct miscdevice ixp4xx_wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &ixp4xx_wdt_fops, }; static int __init ixp4xx_wdt_init(void) { int ret; if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) { pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n"); return -ENODEV; } boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ? WDIOF_CARDRESET : 0; ret = misc_register(&ixp4xx_wdt_miscdev); if (ret == 0) pr_info("timer heartbeat %d sec\n", heartbeat); return ret; } static void __exit ixp4xx_wdt_exit(void) { misc_deregister(&ixp4xx_wdt_miscdev); } module_init(ixp4xx_wdt_init); module_exit(ixp4xx_wdt_exit); MODULE_AUTHOR("Deepak Saxena "); MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog"); module_param(heartbeat, int, 0); MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)"); module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"); MODULE_LICENSE("GPL"); alue='2'>stat only
authorDouglas Miller <dougmill@linux.vnet.ibm.com>2017-01-28 06:42:20 -0600
committerTejun Heo <tj@kernel.org>2017-01-28 07:49:42 -0500
commit966d2b04e070bc040319aaebfec09e0144dc3341 (patch)
tree4b96156e3d1dd4dfd6039b7c219c9dc4616da52d /include/uapi/scsi
parent1b1bc42c1692e9b62756323c675a44cb1a1f9dbd (diff)
percpu-refcount: fix reference leak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'include/uapi/scsi')