linux/include/drm/drm_fb_helper.h
Chris Wilson 752d2635eb drm: Take lock around probes for drm_fb_helper_hotplug_event
We need to hold the dev->mode_config.mutex whilst detecting the output
status. But we also need to drop it for the call into
drm_fb_helper_single_fb_probe(), which indirectly acquires the lock when
attaching the fbcon.

Failure to do so exposes a race with normal output probing. Detected by
adding some warnings that the mutex is held to the backend detect routines:

[   17.772456] WARNING: at drivers/gpu/drm/i915/intel_crt.c:471 intel_crt_detect+0x3e/0x373 [i915]()
[   17.772458] Hardware name: Latitude E6400
[   17.772460] Modules linked in: ....
[   17.772582] Pid: 11, comm: kworker/0:1 Tainted: G        W 2.6.38.4-custom.2 #8
[   17.772584] Call Trace:
[   17.772591]  [<ffffffff81046af5>] ? warn_slowpath_common+0x78/0x8c
[   17.772603]  [<ffffffffa03f3e5c>] ? intel_crt_detect+0x3e/0x373 [i915]
[   17.772612]  [<ffffffffa0355d49>] ?  drm_helper_probe_single_connector_modes+0xbf/0x2af [drm_kms_helper]
[   17.772619]  [<ffffffffa03534d5>] ?  drm_fb_helper_probe_connector_modes+0x39/0x4d [drm_kms_helper]
[   17.772625]  [<ffffffffa0354760>] ?  drm_fb_helper_hotplug_event+0xa5/0xc3 [drm_kms_helper]
[   17.772633]  [<ffffffffa035577f>] ? output_poll_execute+0x146/0x17c [drm_kms_helper]
[   17.772638]  [<ffffffff81193c01>] ? cfq_init_queue+0x247/0x345
[   17.772644]  [<ffffffffa0355639>] ? output_poll_execute+0x0/0x17c [drm_kms_helper]
[   17.772648]  [<ffffffff8105b540>] ? process_one_work+0x193/0x28e
[   17.772652]  [<ffffffff8105c6bc>] ? worker_thread+0xef/0x172
[   17.772655]  [<ffffffff8105c5cd>] ? worker_thread+0x0/0x172
[   17.772658]  [<ffffffff8105c5cd>] ? worker_thread+0x0/0x172
[   17.772663]  [<ffffffff8105f767>] ? kthread+0x7a/0x82
[   17.772668]  [<ffffffff8100a724>] ? kernel_thread_helper+0x4/0x10
[   17.772671]  [<ffffffff8105f6ed>] ? kthread+0x0/0x82
[   17.772674]  [<ffffffff8100a720>] ? kernel_thread_helper+0x0/0x10

Reported-by:  Frederik Himpe <fhimpe@telenet.be>
References: https://bugs.freedesktop.org/show_bug.cgi?id=36394
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2011-05-16 12:01:43 +10:00

123 lines
4.1 KiB
C

/*
* Copyright (c) 2006-2009 Red Hat Inc.
* Copyright (c) 2006-2008 Intel Corporation
* Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
*
* DRM framebuffer helper functions
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*
* Authors:
* Dave Airlie <airlied@linux.ie>
* Jesse Barnes <jesse.barnes@intel.com>
*/
#ifndef DRM_FB_HELPER_H
#define DRM_FB_HELPER_H
struct drm_fb_helper;
#include <linux/kgdb.h>
struct drm_fb_helper_crtc {
uint32_t crtc_id;
struct drm_mode_set mode_set;
struct drm_display_mode *desired_mode;
};
struct drm_fb_helper_surface_size {
u32 fb_width;
u32 fb_height;
u32 surface_width;
u32 surface_height;
u32 surface_bpp;
u32 surface_depth;
};
struct drm_fb_helper_funcs {
void (*gamma_set)(struct drm_crtc *crtc, u16 red, u16 green,
u16 blue, int regno);
void (*gamma_get)(struct drm_crtc *crtc, u16 *red, u16 *green,
u16 *blue, int regno);
int (*fb_probe)(struct drm_fb_helper *helper,
struct drm_fb_helper_surface_size *sizes);
};
struct drm_fb_helper_connector {
struct drm_connector *connector;
struct drm_cmdline_mode cmdline_mode;
};
struct drm_fb_helper {
struct drm_framebuffer *fb;
struct drm_framebuffer *saved_fb;
struct drm_device *dev;
struct drm_display_mode *mode;
int crtc_count;
struct drm_fb_helper_crtc *crtc_info;
int connector_count;
struct drm_fb_helper_connector **connector_info;
struct drm_fb_helper_funcs *funcs;
int conn_limit;
struct fb_info *fbdev;
u32 pseudo_palette[17];
struct list_head kernel_fb_list;
/* we got a hotplug but fbdev wasn't running the console
delay until next set_par */
bool delayed_hotplug;
};
int drm_fb_helper_single_fb_probe(struct drm_fb_helper *helper,
int preferred_bpp);
int drm_fb_helper_init(struct drm_device *dev,
struct drm_fb_helper *helper, int crtc_count,
int max_conn);
void drm_fb_helper_fini(struct drm_fb_helper *helper);
int drm_fb_helper_blank(int blank, struct fb_info *info);
int drm_fb_helper_pan_display(struct fb_var_screeninfo *var,
struct fb_info *info);
int drm_fb_helper_set_par(struct fb_info *info);
int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
struct fb_info *info);
int drm_fb_helper_setcolreg(unsigned regno,
unsigned red,
unsigned green,
unsigned blue,
unsigned transp,
struct fb_info *info);
bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper);
void drm_fb_helper_restore(void);
void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
uint32_t fb_width, uint32_t fb_height);
void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
uint32_t depth);
int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info);
int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper);
bool drm_fb_helper_initial_config(struct drm_fb_helper *fb_helper, int bpp_sel);
int drm_fb_helper_single_add_all_connectors(struct drm_fb_helper *fb_helper);
int drm_fb_helper_debug_enter(struct fb_info *info);
int drm_fb_helper_debug_leave(struct fb_info *info);
#endif