Commits
Ville Syrjälä committed 0c545ac4815
drm: Don't oops in drm_calc_timestamping_constants() if drm_vblank_init() wasn't called
Seems the crtc helpers call drm_calc_timestamping_constants()
unconditionally even if the driver didn't initialize vblank support by
calling drm_vblank_init(). That used to be OK since the constants were
stored under drm_crtc.
However I broke this with
commit eba1f35dfe14 ("drm: Move timestamping constants into drm_vblank_crtc")
when I moved the constants to live inside the drm_vblank_crtc struct
instead. If drm_vblank_init() isn't called, we don't allocate these
structures, and so drm_calc_timestamping_constants() will oops.
Fix it by adding a check into drm_calc_timestamping_constants() to see
if vblank support was initialized at all. And to keep in line with other
such checks, also toss in a check and warn for the case where vblank
support was initialized, but the wrong number of crtcs was specified.
Fixes the following sort of oops:
BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0
IP: [<ffffffffa014b266>] drm_calc_timestamping_constants+0x86/0x130 [drm]
PGD 0
Oops: 0002 [#1] SMP
Modules linked in: sr_mod cdrom mgag200(+) i2c_algo_bit drm_kms_helper ahci syscopyarea sysfillrect sysimgblt libahci fb_sys_fops bnx2x ttm tg3(+) mdio drm ptp sd_mod libata i2c_core pps_core libcrc32c hpsa dm_mirror dm_region_hash dm_log dm_mod
CPU: 0 PID: 418 Comm: kworker/0:2 Not tainted 4.3.0+ #1
Hardware name: HP ProLiant DL380 Gen9, BIOS P89 06/09/2015
Workqueue: events work_for_cpu_fn
task: ffff88046ca95500 ti: ffff88007830c000 task.ti: ffff88007830c000
RIP: 0010:[<ffffffffa014b266>] [<ffffffffa014b266>] drm_calc_timestamping_constants+0x86/0x130 [drm]
RSP: 0018:ffff88007830f4e8 EFLAGS: 00010246
RAX: 0000000000fe4c00 RBX: ffff88006a849160 RCX: 0000000000000540
RDX: 0000000000000000 RSI: 000000000000fde8 RDI: ffff88006a849000
RBP: ffff88007830f518 R08: ffff88007830c000 R09: 00000001b87e3712
R10: 00000000000050c4 R11: 0000000000000000 R12: 0000000000fe4c00
R13: ffff88006a849000 R14: 0000000000000000 R15: 000000000000fde8
FS: 0000000000000000(0000) GS:ffff88046f800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000000b0 CR3: 00000000019d6000 CR4: 00000000001406f0
Stack:
ffff88007830f518 ffff88006a849000 ffff880c69b90340 ffff880c69b90000
ffff880c69b90348 ffff880c69b90340 ffff88007830f748 ffffffffa042f7e7
ffff88006a849090 0000000000000000 ffff88006a849160 0000000000000000
Call Trace:
[<ffffffffa042f7e7>] drm_crtc_helper_set_mode+0x3d7/0x4b0 [drm_kms_helper]
[<ffffffffa04307d4>] drm_crtc_helper_set_config+0x8d4/0xb10 [drm_kms_helper]
[<ffffffffa01548d4>] drm_mode_set_config_internal+0x64/0x100 [drm]
[<ffffffffa043c342>] drm_fb_helper_pan_display+0xa2/0x280 [drm_kms_helper]
[<ffffffff81392c7b>] fb_pan_display+0xbb/0x170
[<ffffffff8138cf70>] bit_update_start+0x20/0x50
[<ffffffff8138b81b>] fbcon_switch+0x39b/0x590
[<ffffffff8140a3d0>] redraw_screen+0x1a0/0x240
[<ffffffff8140b30e>] do_bind_con_driver+0x2ee/0x310
[<ffffffff8140b651>] do_take_over_console+0x141/0x1b0
[<ffffffff81387377>] do_fbcon_takeover+0x57/0xb0
[<ffffffff8138c98b>] fbcon_event_notify+0x60b/0x750
[<ffffffff810a5599>] notifier_call_chain+0x49/0x70
[<ffffffff810a58dd>] __blocking_notifier_call_chain+0x4d/0x70
[<ffffffff810a5916>] blocking_notifier_call_chain+0x16/0x20
[<ffffffff8139282b>] fb_notifier_call_chain+0x1b/0x20
[<ffffffff81394881>] register_framebuffer+0x1f1/0x330
[<ffffffffa043d9aa>] drm_fb_helper_initial_config+0x27a/0x3d0 [drm_kms_helper]
[<ffffffffa0469b4d>] mgag200_fbdev_init+0xdd/0xf0 [mgag200]
[<ffffffffa0468586>] mgag200_modeset_init+0x176/0x1e0 [mgag200]
[<ffffffffa0464659>] mgag200_driver_load+0x3f9/0x580 [mgag200]
[<ffffffffa014e067>] drm_dev_register+0xa7/0xb0 [drm]
[<ffffffffa015054f>] drm_get_pci_dev+0x8f/0x1e0 [drm]
[<ffffffffa046937b>] mga_pci_probe+0x9b/0xc0 [mgag200]
[<ffffffff813662d5>] local_pci_probe+0x45/0xa0
[<ffffffff8109afe4>] work_for_cpu_fn+0x14/0x20
[<ffffffff8109e13c>] process_one_work+0x14c/0x3c0
[<ffffffff8109eaa4>] worker_thread+0x244/0x470
[<ffffffff8168bfba>] ? __schedule+0x2aa/0x760
[<ffffffff8109e860>] ? rescuer_thread+0x310/0x310
[<ffffffff810a4438>] kthread+0xd8/0xf0
[<ffffffff810a4360>] ? kthread_park+0x60/0x60
[<ffffffff8169030f>] ret_from_fork+0x3f/0x70
[<ffffffff810a4360>] ? kthread_park+0x60/0x60
Code: f6 31 d2 41 89 c2 8b 83 b4 00 00 00 0f af c1 48 98 48 69 c0 40 42 0f 00 48 f7 f6 f6 43 74 10 41 89 c4 75 26 f6 05 9a 6f 03 00 01 <45> 89 96 b0 00 00 00 45 89 a6 ac 00 00 00 75 35 48 83 c4 08 5b
RIP [<ffffffffa014b266>] drm_calc_timestamping_constants+0x86/0x130 [drm]
RSP <ffff88007830f4e8>
CR2: 00000000000000b0
Cc: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
References: http://lists.freedesktop.org/archives/dri-devel/2015-November/094217.html
Fixes: eba1f35dfe14 ("drm: Move timestamping constants into drm_vblank_crtc")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>