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] [<ffffffff812c1135>] dump_stack+0x67/0x92
[ 580.239939] [<ffffffff8107419d>] warn_slowpath_common+0x7d/0xb0
[ 580.239959] [<ffffffff810742ba>] warn_slowpath_null+0x1a/0x20
[ 580.239981] [<ffffffff813ce579>] describe_obj+0x419/0x440
[ 580.240006] [<ffffffff813ced22>] i915_gem_framebuffer_info+0xa2/0x100
[ 580.240033] [<ffffffff811a9286>] seq_read+0xe6/0x3b0
[ 580.240059] [<ffffffff81182288>] __vfs_read+0x28/0xd0
[ 580.240085] [<ffffffff81173378>] ? SyS_fadvise64+0x228/0x2c0
[ 580.240112] [<ffffffff811823b2>] vfs_read+0x82/0x110
[ 580.240137] [<ffffffff811827d9>] SyS_read+0x49/0xa0
[ 580.240162] [<ffffffff815bac57>] entry_SYSCALL_64_fastpath+0x12/0x6b
[ 580.240187] ---[ end trace 3e2cbf34576c9878 ]---
[ 580.281900] ------------[ cut here ]------------
---
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 d02f8ce0b1c8..adabbb47a8aa 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 ? "*" : " ",
@@ -1895,6 +1897,11 @@ 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) {
@@ -1929,6 +1936,7 @@ 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;
}
--
2.8.0.rc3
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