/* * Ralink MT7621/MT7628 built-in hardware watchdog timer * * Copyright (C) 2014 John Crispin * * This driver was based on: drivers/watchdog/rt2880_wdt.c * * 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 #include #define SYSC_RSTSTAT 0x38 #define WDT_RST_CAUSE BIT(1) #define RALINK_WDT_TIMEOUT 30 #define TIMER_REG_TMRSTAT 0x00 #define TIMER_REG_TMR1LOAD 0x24 #define TIMER_REG_TMR1CTL 0x20 #define TMR1CTL_ENABLE BIT(7) #define TMR1CTL_RESTART BIT(9) #define TMR1CTL_PRESCALE_SHIFT 16 static void __iomem *mt7621_wdt_base; static struct reset_control *mt7621_wdt_reset; 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 inline void rt_wdt_w32(unsigned reg, u32 val) { iowrite32(val, mt7621_wdt_base + reg); } static inline u32 rt_wdt_r32(unsigned reg) { return ioread32(mt7621_wdt_base + reg); } static int mt7621_wdt_ping(struct watchdog_device *w) { rt_wdt_w32(TIMER_REG_TMRSTAT, TMR1CTL_RESTART); return 0; } static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t) { w->timeout = t; rt_wdt_w32(TIMER_REG_TMR1LOAD, t * 1000); mt7621_wdt_ping(w); return 0; } static int mt7621_wdt_start(struct watchdog_device *w) { u32 t; /* set the prescaler to 1ms == 1000us */ rt_wdt_w32(TIMER_REG_TMR1CTL, 1000 << TMR1CTL_PRESCALE_SHIFT); mt7621_wdt_set_timeout(w, w->timeout); t = rt_wdt_r32(TIMER_REG_TMR1CTL); t |= TMR1CTL_ENABLE; rt_wdt_w32(TIMER_REG_TMR1CTL, t); return 0; } static int mt7621_wdt_stop(struct watchdog_device *w) { u32 t; mt7621_wdt_ping(w); t = rt_wdt_r32(TIMER_REG_TMR1CTL); t &= ~TMR1CTL_ENABLE; rt_wdt_w32(TIMER_REG_TMR1CTL, t); return 0; } static int mt7621_wdt_bootcause(void) { if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE) return WDIOF_CARDRESET; return 0; } static struct watchdog_info mt7621_wdt_info = { .identity = "Mediatek Watchdog", .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, }; static struct watchdog_ops mt7621_wdt_ops = { .owner = THIS_MODULE, .start = mt7621_wdt_start, .stop = mt7621_wdt_stop, .ping = mt7621_wdt_ping, .set_timeout = mt7621_wdt_set_timeout, }; static struct watchdog_device mt7621_wdt_dev = { .info = &mt7621_wdt_info, .ops = &mt7621_wdt_ops, .min_timeout = 1, .max_timeout = 0xfffful / 1000, }; static int mt7621_wdt_probe(struct platform_device *pdev) { struct resource *res; int ret; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); mt7621_wdt_base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(mt7621_wdt_base)) return PTR_ERR(mt7621_wdt_base); mt7621_wdt_reset = devm_reset_control_get(&pdev->dev, NULL); if (!IS_ERR(mt7621_wdt_reset)) reset_control_deassert(mt7621_wdt_reset); mt7621_wdt_dev.bootstatus = mt7621_wdt_bootcause(); watchdog_init_timeout(&mt7621_wdt_dev, mt7621_wdt_dev.max_timeout, &pdev->dev); watchdog_set_nowayout(&mt7621_wdt_dev, nowayout); ret = watchdog_register_device(&mt7621_wdt_dev); return 0; } static int mt7621_wdt_remove(struct platform_device *pdev) { watchdog_unregister_device(&mt7621_wdt_dev); return 0; } static void mt7621_wdt_shutdown(struct platform_device *pdev) { mt7621_wdt_stop(&mt7621_wdt_dev); } static const struct of_device_id mt7621_wdt_match[] = { { .compatible = "mediatek,mt7621-wdt" }, {}, }; MODULE_DEVICE_TABLE(of, mt7621_wdt_match); static struct platform_driver mt7621_wdt_driver = { .probe = mt7621_wdt_probe, .remove = mt7621_wdt_remove, .shutdown = mt7621_wdt_shutdown, .driver = { .name = KBUILD_MODNAME, .of_match_table = mt7621_wdt_match, }, }; module_platform_driver(mt7621_wdt_driver); MODULE_DESCRIPTION("MediaTek MT762x hardware watchdog driver"); MODULE_AUTHOR("John Crispin mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /kernel/smpboot.c
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/smpboot.c')