Re: [PATCH v3,1/2] media: mediatek: vcodec: adding lock to protect decoder context list

[Nicolas Dufresne]

Hi,

Le jeudi 22 février 2024 à 17:26 +0800, Yunfei Dong a écrit :
> The ctx_list will be deleted when scp getting unexpected behavior, then the
> ctx_list->next will be NULL, the kernel driver maybe access NULL pointer in
> function vpu_dec_ipi_handler when going through each context, then reboot.
> 
> Need to add lock to protect the ctx_list to make sure the ctx_list->next isn't
> NULL pointer.

The cited crash no longer occurs for me, but it still sometimes crashes while
the SCP being rebooted. I think this patch can still go in, as it overall
improves the situation.

Meanwhile, here's my stress test using GStreamer and stream downloaded by
fluster. I call this script few times this way as it does not always crash. The
test just keep starting decode sessions and terminate them after 2 seconds. It
is highly parallel. Using too low number does not reproduce the crash, using too
high number leads to alloc failure, which wasn't the goal of this test.

/mtk-vcodec-crash.sh 100

Script code:
***
#!/bin/bash

test() {
	gst-launch-1.0 --no-fault filesrc location=TILES_B_Cisco_1.bin ! h265parse ! v4l2slh265dec ! fakevideosink &
	pid=$!

	sleep 2
	kill $pid
}

for i in $(seq 1 $1)
do
	test &
done

wait
***

The kernel Crash:
[   93.261248] Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000008
[   93.270056] Mem abort info:
[   93.272880]   ESR = 0x0000000096000004
[   93.276804]   EC = 0x25: DABT (current EL), IL = 32 bits
[   93.282233]   SET = 0, FnV = 0
[   93.285372]   EA = 0, S1PTW = 0
[   93.288561]   FSC = 0x04: level 0 translation fault
[   93.293493] Data abort info:
[   93.296424]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[   93.301920]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[   93.306977]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[   93.312321] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000168daf000
[   93.318790] [0000000000000008] pgd=0000000000000000, p4d=0000000000000000
[   93.325588] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[   93.331842] Modules linked in: mt7921e mt7921_common mt792x_lib
mt76_connac_lib mt76 mac80211 btusb btintel mtk_vcodec_dec_hw btmtk btrtl
mtk_vcodec_dec btbcm cfg80211 bluetooth snd_sof_mt8195 mtk_vcodec_enc
mtk_adsp_common uvcvideo v4l2_vp9 snd_sof_xtensa_dsp v4l2_h264 mtk_vcodec_dbgfs
snd_sof_of snd_sof ecdh_generic mtk_vcodec_common ecc uvc elan_i2c
videobuf2_vmalloc crct10dif_ce cros_ec_lid_angle cros_ec_sensors snd_sof_utils
cros_ec_sensors_core cros_usbpd_logger cros_usbpd_charger fuse ip_tables ipv6
[   93.376652] CPU: 5 PID: 3210 Comm: h265parse0:sink Tainted: G        W      
6.8.0-rc4-next-20240212+ #14
[   93.386463] Hardware name: Acer Tomato (rev3 - 4) board (DT)
[   93.392107] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   93.399054] pc : vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
[   93.405058] lr : vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
[   93.410968] sp : ffff80008750bc20
[   93.414269] x29: ffff80008750bc20 x28: ffff1299f6d70000 x27: 0000000000000000
[   93.421391] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
[   93.428512] x23: ffff80008750bc98 x22: 000000000000a003 x21: ffffd45c4cfae000
[   93.435632] x20: 0000000000000010 x19: ffff1299fd668310 x18: 000000000000001a
[   93.442753] x17: 000000040044ffff x16: ffffd45cb15dc648 x15: 0000000000000000
[   93.449874] x14: ffff1299c08da1c0 x13: ffffd45cb1f87a10 x12: ffffd45cb2f5fe80
[   93.456995] x11: 0000000000000001 x10: 0000000000001b30 x9 : ffffd45c4d12b488
[   93.464116] x8 : 1fffe25339380d81 x7 : 0000000000000001 x6 : ffff1299c9c06c00
[   93.471236] x5 : 0000000000000132 x4 : 0000000000000000 x3 : 0000000000000000
[   93.478358] x2 : 0000000000000010 x1 : ffff80008750bc98 x0 : 0000000000000000
[   93.485479] Call trace:
[   93.487914]  vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
[   93.493563]  vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
[   93.499125]  vpu_dec_deinit+0x1c/0x30 [mtk_vcodec_dec]
[   93.504254]  vdec_hevc_slice_deinit+0x30/0x98 [mtk_vcodec_dec]
[   93.510076]  vdec_if_deinit+0x38/0x68 [mtk_vcodec_dec]
[   93.515205]  mtk_vcodec_dec_release+0x20/0x40 [mtk_vcodec_dec]
[   93.521027]  fops_vcodec_release+0x64/0x118 [mtk_vcodec_dec]
[   93.526677]  v4l2_release+0x7c/0x100
[   93.530245]  __fput+0x80/0x2d8
[   93.533292]  __fput_sync+0x58/0x70
[   93.536681]  __arm64_sys_close+0x40/0x90
[   93.540590]  invoke_syscall+0x50/0x128
[   93.544329]  el0_svc_common.constprop.0+0x48/0xf0
[   93.549020]  do_el0_svc+0x24/0x38
[   93.552323]  el0_svc+0x38/0xd8
[   93.555367]  el0t_64_sync_handler+0xc0/0xc8
[   93.559537]  el0t_64_sync+0x1a8/0x1b0
[   93.563189] Code: d503201f f9401660 b900127f b900227f (f9400400) 
[   93.569268] ---[ end trace 0000000000000000 ]---