For some reason, every single time I try to run module_reload
something tries to read the connector sysfs files. This happens
after we destroy the encoders and before we destroy the connectors, so
when the sysfs read triggers the connector detect() function,
intel_conector->encoder points to memory that was already freed.
The bad backtrace is just:
[<ffffffff8163ca9a>] dump_stack+0x54/0x74
[<ffffffffa00c2c8e>] intel_dp_detect+0x1e/0x4b0 [i915]
[<ffffffffa001913d>] status_show+0x3d/0x80 [drm]
[<ffffffff813d5340>] dev_attr_show+0x20/0x60
[<ffffffff81221f50>] ? sysfs_read_file+0x80/0x1b0
[<ffffffff81221f79>] sysfs_read_file+0xa9/0x1b0
[<ffffffff811aaf1e>] vfs_read+0x9e/0x170
[<ffffffff811aba4c>] SyS_read+0x4c/0xa0
[<ffffffff8164e392>] system_call_fastpath+0x16/0x1b
But if you add tons of memory checking debug options to your Kernel
you'll also see:
- general protection fault: 0000
- BUG kmalloc-4096 (Tainted: G D W ): Poison overwritten
- INFO: Allocated in intel_ddi_init+0x65/0x270 [i915]
- INFO: Freed in intel_dp_encoder_destroy+0x69/0xb0 [i915]
Among a bunch of other error messages.
So this commit just destroys the sysfs files before both the encoder
and connectors are freed.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************
* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
************************************************************
The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html
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