/* * Watchdog timer driver for the WinSystems EBC-C384 * Copyright (C) 2016 William Breathitt Gray * * 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. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */ #include #include #include #include #include #include #include #include #include #include #include #define MODULE_NAME "ebc-c384_wdt" #define WATCHDOG_TIMEOUT 60 /* * The timeout value in minutes must fit in a single byte when sent to the * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds. */ #define WATCHDOG_MAX_TIMEOUT 15300 #define BASE_ADDR 0x564 #define ADDR_EXTENT 5 #define CFG_ADDR (BASE_ADDR + 1) #define PET_ADDR (BASE_ADDR + 2) static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); static unsigned timeout; module_param(timeout, uint, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); static int ebc_c384_wdt_start(struct watchdog_device *wdev) { unsigned t = wdev->timeout; /* resolution is in minutes for timeouts greater than 255 seconds */ if (t > 255) t = DIV_ROUND_UP(t, 60); outb(t, PET_ADDR); return 0; } static int ebc_c384_wdt_stop(struct watchdog_device *wdev) { outb(0x00, PET_ADDR); return 0; } static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t) { /* resolution is in minutes for timeouts greater than 255 seconds */ if (t > 255) { /* round second resolution up to minute granularity */ wdev->timeout = roundup(t, 60); /* set watchdog timer for minutes */ outb(0x00, CFG_ADDR); } else { wdev->timeout = t; /* set watchdog timer for seconds */ outb(0x80, CFG_ADDR); } return 0; } static const struct watchdog_ops ebc_c384_wdt_ops = { .start = ebc_c384_wdt_start, .stop = ebc_c384_wdt_stop, .set_timeout = ebc_c384_wdt_set_timeout }; static const struct watchdog_info ebc_c384_wdt_info = { .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT, .identity = MODULE_NAME }; static int ebc_c384_wdt_probe(struct device *dev, unsigned int id) { struct watchdog_device *wdd; if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) { dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n", BASE_ADDR, BASE_ADDR + ADDR_EXTENT); return -EBUSY; } wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL); if (!wdd) return -ENOMEM; wdd->info = &ebc_c384_wdt_info; wdd->ops = &ebc_c384_wdt_ops; wdd->timeout = WATCHDOG_TIMEOUT; wdd->min_timeout = 1; wdd->max_timeout = WATCHDOG_MAX_TIMEOUT; watchdog_set_nowayout(wdd, nowayout); if (watchdog_init_timeout(wdd, timeout, dev)) dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n", timeout, WATCHDOG_TIMEOUT); dev_set_drvdata(dev, wdd); return watchdog_register_device(wdd); } static int ebc_c384_wdt_remove(struct device *dev, unsigned int id) { struct watchdog_device *wdd = dev_get_drvdata(dev); watchdog_unregister_device(wdd); return 0; } static struct isa_driver ebc_c384_wdt_driver = { .probe = ebc_c384_wdt_probe, .driver = { .name = MODULE_NAME }, .remove = ebc_c384_wdt_remove }; static int __init ebc_c384_wdt_init(void) { if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC")) return -ENODEV; return isa_register_driver(&ebc_c384_wdt_driver, 1); } static void __exit ebc_c384_wdt_exit(void) { isa_unregister_driver(&ebc_c384_wdt_driver); } module_init(ebc_c384_wdt_init); module_exit(ebc_c384_wdt_exit); MODULE_AUTHOR("William Breathitt Gray "); MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("isa:" MODULE_NAME); ace:mode:
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 /net/tipc/ib_media.c
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 'net/tipc/ib_media.c')