Re: [PATCH v2 1/3] venus: core: handle race condititon for core ops
On 2020-09-11 15:40, Stanimir Varbanov wrote: On 9/10/20 3:44 PM, Mansur Alisha Shaik wrote: 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 Acked-by: Stanimir Varbanov --- Changes in V2: - Addressed review comments by stan by validating on top - of https://lore.kernel.org/patchwork/project/lkml/list/?series=455962 drivers/media/platform/qcom/venus/hfi.c | 5 - 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c index a59022a..3137071 100644 --- a/drivers/media/platform/qcom/venus/hfi.c +++ b/drivers/media/platform/qcom/venus/hfi.c @@ -195,7 +195,7 @@ 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 we are in system error recovery the session_init cannot pass successfully, so we exit early in the function. I'd suggest to make it: /* If core shutdown is in progress or we are in system error recovery, return an error */ mutex_lock(>lock); if (!core->ops || core->sys_error) { mutex_unclock(>lock); return -EIO; } mutex_unclock(>lock); Tried above suggestion and ran the failed scenario, I didn't see any issue. Posted new version https://lore.kernel.org/patchwork/project/lkml/list/?series=463091 if (inst->state != INST_UNINIT) @@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 pixfmt) inst->hfi_codec = to_codec_type(pixfmt); reinit_completion(>done); + mutex_lock(>lock); + ops = core->ops; ret = ops->session_init(inst, inst->session_type, inst->hfi_codec); if (ret) return ret; + mutex_unlock(>lock); ret = wait_session_msg(inst); if (ret) return ret;
Re: [PATCH v2 1/3] venus: core: handle race condititon for core ops
On 9/10/20 3:44 PM, Mansur Alisha Shaik wrote: > 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 > Acked-by: Stanimir Varbanov > --- > Changes in V2: > - Addressed review comments by stan by validating on top > - of https://lore.kernel.org/patchwork/project/lkml/list/?series=455962 > > drivers/media/platform/qcom/venus/hfi.c | 5 - > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/platform/qcom/venus/hfi.c > b/drivers/media/platform/qcom/venus/hfi.c > index a59022a..3137071 100644 > --- a/drivers/media/platform/qcom/venus/hfi.c > +++ b/drivers/media/platform/qcom/venus/hfi.c > @@ -195,7 +195,7 @@ 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 we are in system error recovery the session_init cannot pass successfully, so we exit early in the function. I'd suggest to make it: /* If core shutdown is in progress or we are in system error recovery, return an error */ mutex_lock(>lock); if (!core->ops || core->sys_error) { mutex_unclock(>lock); return -EIO; } mutex_unclock(>lock); > if (inst->state != INST_UNINIT) > @@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 > pixfmt) > inst->hfi_codec = to_codec_type(pixfmt); > reinit_completion(>done); > > + mutex_lock(>lock); > + ops = core->ops; > ret = ops->session_init(inst, inst->session_type, inst->hfi_codec); > if (ret) > return ret; > > + mutex_unlock(>lock); > ret = wait_session_msg(inst); > if (ret) > return ret; > -- regards, Stan
[PATCH v2 1/3] venus: core: handle race condititon for core ops
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 Acked-by: Stanimir Varbanov --- Changes in V2: - Addressed review comments by stan by validating on top - of https://lore.kernel.org/patchwork/project/lkml/list/?series=455962 drivers/media/platform/qcom/venus/hfi.c | 5 - 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/media/platform/qcom/venus/hfi.c b/drivers/media/platform/qcom/venus/hfi.c index a59022a..3137071 100644 --- a/drivers/media/platform/qcom/venus/hfi.c +++ b/drivers/media/platform/qcom/venus/hfi.c @@ -195,7 +195,7 @@ 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 (inst->state != INST_UNINIT) @@ -204,10 +204,13 @@ int hfi_session_init(struct venus_inst *inst, u32 pixfmt) inst->hfi_codec = to_codec_type(pixfmt); reinit_completion(>done); + mutex_lock(>lock); + ops = core->ops; ret = ops->session_init(inst, inst->session_type, inst->hfi_codec); if (ret) return ret; + mutex_unlock(>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