On Tue, 8 Mar 2022 19:13:08 +0800 Yicong Yang <[email protected]> wrote:
> On 2022/3/8 18:21, Jonathan Cameron wrote: > > On Tue, 8 Mar 2022 16:49:25 +0800 > > Yicong Yang <[email protected]> wrote: > > > >> Register PMU device of PTT trace, then users can use trace through perf > >> command. The driver makes use of perf AUX trace and support following > >> events to configure the trace: > >> > >> - filter: select Root port or Endpoint to trace > >> - type: select the type of traced TLP headers > >> - direction: select the direction of traced TLP headers > >> - format: select the data format of the traced TLP headers > >> > >> This patch adds the PMU driver part of PTT trace. The perf command support > >> of PTT trace is added in the following patch. > >> > >> Signed-off-by: Yicong Yang <[email protected]> > > > > It seems to me that you ended up doing both suggestions for > > how to clean up the remove order when it was meant to be > > a question of picking one or the other. > > > > Otherwise this looks good to me - so with that tidied up > > > > Hi Jonathan, > > Thanks for the comments. I'd like to illustrate the reason why I decide to > manually unregister the PMU device. > > The DMA buffers are devm allocated when necessary. They're only allocated > when user is going to use the PTT in the first time after the driver's probe, > so when driver removal the buffers are released prior to the PMU device's > unregistration. I think there's a race condition. > > IIUC, The PMU device(as the user interface) should be unregistered first then > we're safe to free the DMA buffers. But unregister the PMU device by devm > cannot keep that order. Ok. Please add a comment in the remove() giving this reasoning. Jonathan > > Thanks, > Yicong > > > Reviewed-by: Jonathan Cameron <[email protected]> > > > >> --- > > > >> + > >> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt) > >> +{ > >> + u16 core_id, sicl_id; > >> + char *pmu_name; > >> + u32 reg; > >> + > >> + hisi_ptt->hisi_ptt_pmu = (struct pmu) { > >> + .module = THIS_MODULE, > >> + .capabilities = PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE, > >> + .task_ctx_nr = perf_sw_context, > >> + .attr_groups = hisi_ptt_pmu_groups, > >> + .event_init = hisi_ptt_pmu_event_init, > >> + .setup_aux = hisi_ptt_pmu_setup_aux, > >> + .free_aux = hisi_ptt_pmu_free_aux, > >> + .start = hisi_ptt_pmu_start, > >> + .stop = hisi_ptt_pmu_stop, > >> + .add = hisi_ptt_pmu_add, > >> + .del = hisi_ptt_pmu_del, > >> + }; > >> + > >> + reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION); > >> + core_id = FIELD_GET(HISI_PTT_CORE_ID, reg); > >> + sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg); > >> + > >> + pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, > >> "hisi_ptt%u_%u", > >> + sicl_id, core_id); > >> + if (!pmu_name) > >> + return -ENOMEM; > >> + > >> + return perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1); > > > > As below, you can put back the devm cleanup that you had in v4 now you > > have modified how the filter cleanup is done to also be devm managed. > > > >> +} > >> + > >> /* > >> * The DMA of PTT trace can only use direct mapping, due to some > >> * hardware restriction. Check whether there is an IOMMU or the > >> @@ -303,15 +825,32 @@ static int hisi_ptt_probe(struct pci_dev *pdev, > >> > >> pci_set_master(pdev); > >> > >> + ret = hisi_ptt_register_irq(hisi_ptt); > >> + if (ret) > >> + return ret; > >> + > >> ret = hisi_ptt_init_ctrls(hisi_ptt); > >> if (ret) { > >> pci_err(pdev, "failed to init controls, ret = %d.\n", ret); > >> return ret; > >> } > >> > >> + ret = hisi_ptt_register_pmu(hisi_ptt); > >> + if (ret) { > >> + pci_err(pdev, "failed to register pmu device, ret = %d", ret); > >> + return ret; > >> + } > >> + > >> return 0; > >> } > >> > >> +void hisi_ptt_remove(struct pci_dev *pdev) > >> +{ > >> + struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev); > >> + > >> + perf_pmu_unregister(&hisi_ptt->hisi_ptt_pmu); > > > > Now you have the filter cleanup occurring using a devm_add_action_or_reset() > > there is no need to have a manual cleanup of this - you can > > use the approach of a devm_add_action_or_reset like you had in v4. > > > > As it is the last call in the probe() order it will be the first one > > called in the device managed cleanup. > > > >> +} > >> + > > > > > > . > > _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
