For core ops we are having only write protect but there is no read protect, because of this in multthreading and concurrency, one CPU core is reading without wait which is causing the NULL pointer dereferece crash.
one such scenario is as show below, where in one CPU core, core->ops becoming NULL and in another CPU core calling core->ops->session_init(). CPU: core-7: Call trace: hfi_session_init+0x180/0x1dc [venus_core] vdec_queue_setup+0x9c/0x364 [venus_dec] vb2_core_reqbufs+0x1e4/0x368 [videobuf2_common] vb2_reqbufs+0x4c/0x64 [videobuf2_v4l2] v4l2_m2m_reqbufs+0x50/0x84 [v4l2_mem2mem] v4l2_m2m_ioctl_reqbufs+0x2c/0x38 [v4l2_mem2mem] v4l_reqbufs+0x4c/0x5c __video_do_ioctl+0x2b0/0x39c CPU: core-0: Call trace: venus_shutdown+0x98/0xfc [venus_core] venus_sys_error_handler+0x64/0x148 [venus_core] process_one_work+0x210/0x3d0 worker_thread+0x248/0x3f4 kthread+0x11c/0x12c Signed-off-by: Mansur Alisha Shaik <man...@codeaurora.org> Acked-by: Stanimir Varbanov <stanimir.varba...@linaro.org> --- Changes in V4: - Addressed review comments by Stan in patch series https://lore.kernel.org/patchwork/patch/1303678/ and combining this change along with shutdown callback as we are facing race conditions with shutdown callback drivers/media/platform/qcom/venus/hfi.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c index a59022a..58d4c06 100644 --- a/drivers/media/platform/qcom/venus/hfi.c +++ b/drivers/media/platform/qcom/venus/hfi.c @@ -195,19 +195,34 @@ EXPORT_SYMBOL_GPL(hfi_session_create); int hfi_session_init(struct venus_inst *inst, u32 pixfmt) { struct venus_core *core = inst->core; - const struct hfi_ops *ops = core->ops; + const struct hfi_ops *ops; int ret; + /* + * If core shutdown is in progress or if we are in system + * recovery, return an error as during system error recovery + * session_init() can't pass successfully + */ + mutex_lock(&core->lock); + if (!core->ops || core->sys_error) { + mutex_unlock(&core->lock); + return -EIO; + } + mutex_unlock(&core->lock); + if (inst->state != INST_UNINIT) return -EINVAL; inst->hfi_codec = to_codec_type(pixfmt); reinit_completion(&inst->done); + mutex_lock(&core->lock); + ops = core->ops; ret = ops->session_init(inst, inst->session_type, inst->hfi_codec); if (ret) return ret; + mutex_unlock(&core->lock); ret = wait_session_msg(inst); if (ret) return ret; -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
