/* * Copyright (C) 2009-2010, Lars-Peter Clausen * PCF50633 backlight device driver * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include #include #include #include #include #include #include #include struct pcf50633_bl { struct pcf50633 *pcf; struct backlight_device *bl; unsigned int brightness; unsigned int brightness_limit; }; /* * pcf50633_bl_set_brightness_limit * * Update the brightness limit for the pc50633 backlight. The actual brightness * will not go above the limit. This is useful to limit power drain for example * on low battery. * * @dev: Pointer to a pcf50633 device * @limit: The brightness limit. Valid values are 0-63 */ int pcf50633_bl_set_brightness_limit(struct pcf50633 *pcf, unsigned int limit) { struct pcf50633_bl *pcf_bl = platform_get_drvdata(pcf->bl_pdev); if (!pcf_bl) return -ENODEV; pcf_bl->brightness_limit = limit & 0x3f; backlight_update_status(pcf_bl->bl); return 0; } static int pcf50633_bl_update_status(struct backlight_device *bl) { struct pcf50633_bl *pcf_bl = bl_get_data(bl); unsigned int new_brightness; if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK) || bl->props.power != FB_BLANK_UNBLANK) new_brightness = 0; else if (bl->props.brightness < pcf_bl->brightness_limit) new_brightness = bl->props.brightness; else new_brightness = pcf_bl->brightness_limit; if (pcf_bl->brightness == new_brightness) return 0; if (new_brightness) { pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDOUT, new_brightness); if (!pcf_bl->brightness) pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 1); } else { pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDENA, 0); } pcf_bl->brightness = new_brightness; return 0; } static int pcf50633_bl_get_brightness(struct backlight_device *bl) { struct pcf50633_bl *pcf_bl = bl_get_data(bl); return pcf_bl->brightness; } static const struct backlight_ops pcf50633_bl_ops = { .get_brightness = pcf50633_bl_get_brightness, .update_status = pcf50633_bl_update_status, .options = BL_CORE_SUSPENDRESUME, }; static int pcf50633_bl_probe(struct platform_device *pdev) { struct pcf50633_bl *pcf_bl; struct device *parent = pdev->dev.parent; struct pcf50633_platform_data *pcf50633_data = dev_get_platdata(parent); struct pcf50633_bl_platform_data *pdata = pcf50633_data->backlight_data; struct backlight_properties bl_props; pcf_bl = devm_kzalloc(&pdev->dev, sizeof(*pcf_bl), GFP_KERNEL); if (!pcf_bl) return -ENOMEM; memset(&bl_props, 0, sizeof(bl_props)); bl_props.type = BACKLIGHT_RAW; bl_props.max_brightness = 0x3f; bl_props.power = FB_BLANK_UNBLANK; if (pdata) { bl_props.brightness = pdata->default_brightness; pcf_bl->brightness_limit = pdata->default_brightness_limit; } else { bl_props.brightness = 0x3f; pcf_bl->brightness_limit = 0x3f; } pcf_bl->pcf = dev_to_pcf50633(pdev->dev.parent); pcf_bl->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, pcf_bl, &pcf50633_bl_ops, &bl_props); if (IS_ERR(pcf_bl->bl)) return PTR_ERR(pcf_bl->bl); platform_set_drvdata(pdev, pcf_bl); pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time); /* * Should be different from bl_props.brightness, so we do not exit * update_status early the first time it's called */ pcf_bl->brightness = pcf_bl->bl->props.brightness + 1; backlight_update_status(pcf_bl->bl); return 0; } static struct platform_driver pcf50633_bl_driver = { .probe = pcf50633_bl_probe, .driver = { .name = "pcf50633-backlight", }, }; module_platform_driver(pcf50633_bl_driver); MODULE_AUTHOR("Lars-Peter Clausen "); MODULE_DESCRIPTION("PCF50633 backlight driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:pcf50633-backlight"); ='reload'/>
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/sched/ematch.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/sched/ematch.c')