On Sun, Feb 15, 2015 at 04:52:39PM -0800, Aaron Plattner wrote:

vblank_disable_and_save calls the driver's disable_vblank hook unconditionally, which crashes the udl driver since it doesn't implement it. Fix this by adding stub implementations of these functions identical to the qxl ones.

usb 5-1: USB disconnect, device number 2 BUG: unable to handle kernel NULL pointer dereference at (null) IP: [< (null)>] (null) PGD 3bc23d067 PUD 3bc0fc067 PMD 0 Oops: 0010 [#1] PREEMPT SMP Modules linked in: udlfb fb_sys_fops nvidia(PO) udl drm_kms_helper drm syscopyarea sysfillrect sysimgblt netconsole cfg80211 joydev mousedev nls_iso8859_1 nls_cp437 vfat fat coretemp intel_rapl eeepc_wmi asus_wmi sparse_keymap led_class rfkill hwmon iosf_mbi x86_pkg_temp_thermal intel_powerclamp iTCO_wdt iTCO_vendor_support evdev kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel mac_hid tpm_infineon aes_x86_64 lrw gf128mul e1000e glue_helper ablk_helper cryptd mxm_wmi tpm_tis processor psmouse ptp serio_raw tpm snd_hda_codec_hdmi i2c_i801 i2c_core lpc_ich pps_core pcspkr snd_hda_codec_realtek snd_hda_codec_generic mei_me mei snd_hda_intel snd_hda_controller snd_hda_codec snd_hwdep snd_pcm snd_timer snd ie31200_edac edac_core soundcore thermal shpchp battery video wmi button fan sch_fq_codel nfs lockd grace sunrpc fscache btrfs xor raid6_pq hid_generic usbhid hid sd_mod atkbd libps2 ahci libahci crc32c_intel xhci_pci libata ehci_pci xhci_hcd ehci_hcd scsi_mod usbcore usb_common i8042 serio [last unloaded: drm] CPU: 2 PID: 2044 Comm: Xorg.bin Tainted: P O 3.19.0-1-agp #1 Hardware name: System manufacturer System Product Name/P8Z77-V, BIOS 2104 08/13/2013 task: ffff8803f99d27c0 ti: ffff8803bc1c4000 task.ti: ffff8803bc1c4000 RIP: 0010:[<0000000000000000>] [< (null)>] (null) RSP: 0018:ffff8803bc1c7d00 EFLAGS: 00010046 RAX: ffffffffa06d0140 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 000000000000cee6 RSI: 0000000000000000 RDI: ffff8804037c3000 RBP: ffff8803bc1c7d88 R08: 000000000047b69a R09: 0000000000000000 R10: ffffffffa06de187 R11: 0000000000003246 R12: ffff880403d74540 R13: 0000000000000003 R14: ffff8804037c3000 R15: ffff8803bc32eac8 FS: 00007f7f4753a900(0000) GS:ffff88041ec80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000003bc240000 CR4: 00000000001407e0 Stack: ffffffffa06e06da ffff8803bc1c7d38 0000000000000000 0000000000000082 ffff8804037c3188 ffff8803bc1c7d40 0000000000000282 ffff8803bc1c7d68 0000000000000106 000000000000cee6 00000000f69756fa ffff880403d74580 Call Trace: [<ffffffffa06e06da>] ? vblank_disable_and_save+0x9a/0x200 [drm] [<ffffffffa06e2205>] drm_vblank_cleanup+0x65/0xb0 [drm] [<ffffffffa06cc338>] udl_driver_unload+0x18/0x50 [udl] [<ffffffffa06e3f2d>] drm_dev_unregister+0x2d/0xb0 [drm] [<ffffffffa06e41e7>] drm_put_dev+0x27/0x70 [drm] [<ffffffffa06de237>] drm_release+0x347/0x520 [drm] [<ffffffff811d357f>] __fput+0x9f/0x200 [<ffffffff811d372e>] ____fput+0xe/0x10 [<ffffffff8108fc87>] task_work_run+0xb7/0xf0 [<ffffffff81015d35>] do_notify_resume+0x95/0xa0 [<ffffffff8155f060>] int_signal+0x12/0x17 Code: Bad RIP value. RIP [< (null)>] (null) RSP <ffff8803bc1c7d00> CR2: 0000000000000000 ---[ end trace e0b184ca053571af ]---

Reported-by: Thomas Meyer thomas@m3y3r.de Link: http://lists.freedesktop.org/archives/dri-devel/2014-December/073652.html Signed-off-by: Aaron Plattner aplattner@nvidia.com

---

Daniel, it looks like your change "[5/5] drm/irq: Don't call ->get_vblank_counter directly from irq_uninstall/cleanup" masks the immediate problem, but it's not clear to me whether that's just because I didn't manage to trigger any of the new vblank stuff, or whether your change really fixes it. It does seem like these vblank functions are intended to be called unconditionally.

On a quick look udl vblank handling seems to be 100% cargo-cult. It never calls handle_vblank, which means there's never going to be a useful vblank timestamp/counter value, but it also doesn't use the -1 trick for drm_send_vblank_event used to signal that just grabbing a cpu ts is all that's possible.

I think the right fix here is to ditch both the vblank_init and cleanup and use -1 in drm_send_vblank_event. -Daniel

drivers/gpu/drm/udl/udl_drv.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c index d5728ec85254..5bacb556b0f5 100644 --- a/drivers/gpu/drm/udl/udl_drv.c +++ b/drivers/gpu/drm/udl/udl_drv.c @@ -16,6 +16,20 @@ static int udl_driver_set_busid(struct drm_device *d, struct drm_master *m) return 0; }

+static u32 udl_noop_get_vblank_counter(struct drm_device *dev, int crtc) +{

• return dev->vblank[crtc].count.counter;

+}

+static int udl_noop_enable_vblank(struct drm_device *dev, int crtc) +{

• return 0;

+}

+static void udl_noop_disable_vblank(struct drm_device *dev, int crtc) +{ +}

static const struct vm_operations_struct udl_gem_vm_ops = { .fault = udl_gem_fault, .open = drm_gem_vm_open, @@ -42,6 +56,10 @@ static struct drm_driver driver = { .unload = udl_driver_unload, .set_busid = udl_driver_set_busid,

• .get_vblank_counter = udl_noop_get_vblank_counter,
• .enable_vblank = udl_noop_enable_vblank,
• .disable_vblank = udl_noop_disable_vblank,
• /* gem hooks */ .gem_free_object = udl_gem_free_object, .gem_vm_ops = &udl_gem_vm_ops,

-- 2.3.0