From 188c1ab7769dd7c092f9b1be5f69aa34d4a6f9d6 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sun, 3 Apr 2016 14:14:20 +0100 Subject: [PATCH] drm/i915: Add struct_mutex locking for debugs/i915_gem_framebuffer Since describe_obj() looks at state guarded by the struct_mutex, we need to be holding it. [ 580.201054] drv_suspend: starting subtest debugfs-reader [ 580.239652] ------------[ cut here ]------------ [ 580.239696] WARNING: CPU: 0 PID: 920 at include/linux/list_check.h:25 describe_obj+0x419/0x440() [ 580.239725] CPU: 0 PID: 920 Comm: cat Not tainted 4.5.0-rc6+ #835 [ 580.239745] Hardware name: /NUC5CPYB, BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015 [ 580.239767] 0000000000000000 ffff88027554fcf8 ffffffff812c1135 0000000000000000 [ 580.239815] ffffffff8193dc42 ffff88027554fd30 ffffffff8107419d ffff880071727c00 [ 580.239858] ffff8802757d8000 ffffffff818f693c ffffffff818f693c ffff8802757b9048 [ 580.239896] Call Trace: [ 580.239917] [] dump_stack+0x67/0x92 [ 580.239939] [] warn_slowpath_common+0x7d/0xb0 [ 580.239959] [] warn_slowpath_null+0x1a/0x20 [ 580.239981] [] describe_obj+0x419/0x440 [ 580.240006] [] i915_gem_framebuffer_info+0xa2/0x100 [ 580.240033] [] seq_read+0xe6/0x3b0 [ 580.240059] [] __vfs_read+0x28/0xd0 [ 580.240085] [] ? SyS_fadvise64+0x228/0x2c0 [ 580.240112] [] vfs_read+0x82/0x110 [ 580.240137] [] SyS_read+0x49/0xa0 [ 580.240162] [] entry_SYSCALL_64_fastpath+0x12/0x6b [ 580.240187] ---[ end trace 3e2cbf34576c9878 ]--- [ 580.281900] ------------[ cut here ]------------ Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1459689261-7920-1-git-send-email-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_debugfs.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 74f2274..6b384d7 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -134,6 +134,8 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj) int pin_count = 0; enum intel_engine_id id; + lockdep_assert_held(&obj->base.dev->struct_mutex); + seq_printf(m, "%pK: %s%s%s%s %8zdKiB %02x %02x [ ", &obj->base, obj->active ? "*" : " ", @@ -1894,6 +1896,11 @@ static int i915_gem_framebuffer_info(struct seq_file *m, void *data) struct drm_device *dev = node->minor->dev; struct intel_framebuffer *fbdev_fb = NULL; struct drm_framebuffer *drm_fb; + int ret; + + ret = mutex_lock_interruptible(&dev->struct_mutex); + if (ret) + return ret; #ifdef CONFIG_DRM_FBDEV_EMULATION if (to_i915(dev)->fbdev) { @@ -1928,6 +1935,7 @@ static int i915_gem_framebuffer_info(struct seq_file *m, void *data) seq_putc(m, '\n'); } mutex_unlock(&dev->mode_config.fb_lock); + mutex_unlock(&dev->struct_mutex); return 0; } -- 2.7.4