Messages in this thread | | | Date | Wed, 16 May 2018 20:28:39 +0530 | From | poza@codeauro ... | Subject | Re: [PATCH v16 8/9] PCI/DPC: Unify and plumb error handling into DPC |
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On 2018-05-16 18:34, Bjorn Helgaas wrote: > On Wed, May 16, 2018 at 05:45:58PM +0530, poza@codeaurora.org wrote: >> On 2018-05-16 16:22, Bjorn Helgaas wrote: >> > On Wed, May 16, 2018 at 01:46:25PM +0530, poza@codeaurora.org wrote: >> > > On 2018-05-16 05:26, Bjorn Helgaas wrote: >> > > > On Fri, May 11, 2018 at 05:22:08PM +0530, poza@codeaurora.org wrote: >> > > > > On 2018-05-11 16:13, Oza Pawandeep wrote: >> > > > > > DPC driver implements link_reset callback, and calls >> > > > > > pci_do_fatal_recovery(). >> > > > > > >> > > > > > Which follows standard path of ERR_FATAL recovery. >> > > > > > >> > > > > > Signed-off-by: Oza Pawandeep <poza@codeaurora.org> >> > > > > > >> > > > > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h >> > > > > > index 5e8857a..6af7595 100644 >> > > > > > --- a/drivers/pci/pci.h >> > > > > > +++ b/drivers/pci/pci.h >> > > > > > @@ -354,7 +354,7 @@ static inline resource_size_t >> > > > > > pci_resource_alignment(struct pci_dev *dev, >> > > > > > void pci_enable_acs(struct pci_dev *dev); >> > > > > > >> > > > > > /* PCI error reporting and recovery */ >> > > > > > -void pcie_do_fatal_recovery(struct pci_dev *dev); >> > > > > > +void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service); >> > > > > > void pcie_do_nonfatal_recovery(struct pci_dev *dev); >> > > > > > >> > > > > > bool pcie_wait_for_link(struct pci_dev *pdev, bool active); >> > > > > > diff --git a/drivers/pci/pcie/aer/aerdrv_core.c >> > > > > > b/drivers/pci/pcie/aer/aerdrv_core.c >> > > > > > index fdfc474..36e622d 100644 >> > > > > > --- a/drivers/pci/pcie/aer/aerdrv_core.c >> > > > > > +++ b/drivers/pci/pcie/aer/aerdrv_core.c >> > > > > > @@ -254,7 +254,7 @@ static void handle_error_source(struct pcie_device >> > > > > > *aerdev, >> > > > > > } else if (info->severity == AER_NONFATAL) >> > > > > > pcie_do_nonfatal_recovery(dev); >> > > > > > else if (info->severity == AER_FATAL) >> > > > > > - pcie_do_fatal_recovery(dev); >> > > > > > + pcie_do_fatal_recovery(dev, PCIE_PORT_SERVICE_AER); >> > > > > > } >> > > > > > >> > > > > > #ifdef CONFIG_ACPI_APEI_PCIEAER >> > > > > > @@ -321,7 +321,7 @@ static void aer_recover_work_func(struct work_struct >> > > > > > *work) >> > > > > > if (entry.severity == AER_NONFATAL) >> > > > > > pcie_do_nonfatal_recovery(pdev); >> > > > > > else if (entry.severity == AER_FATAL) >> > > > > > - pcie_do_fatal_recovery(pdev); >> > > > > > + pcie_do_fatal_recovery(pdev, PCIE_PORT_SERVICE_AER); >> > > > > > pci_dev_put(pdev); >> > > > > > } >> > > > > > } >> > > > > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c >> > > > > > index 80ec384..5680c13 100644 >> > > > > > --- a/drivers/pci/pcie/dpc.c >> > > > > > +++ b/drivers/pci/pcie/dpc.c >> > > > > > @@ -73,29 +73,31 @@ static void dpc_wait_link_inactive(struct dpc_dev >> > > > > > *dpc) >> > > > > > pcie_wait_for_link(pdev, false); >> > > > > > } >> > > > > > >> > > > > > -static void dpc_work(struct work_struct *work) >> > > > > > +static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev) >> > > > > > { >> > > > > > - struct dpc_dev *dpc = container_of(work, struct dpc_dev, work); >> > > > > > - struct pci_dev *dev, *temp, *pdev = dpc->dev->port; >> > > > > > - struct pci_bus *parent = pdev->subordinate; >> > > > > > - u16 cap = dpc->cap_pos, ctl; >> > > > > > - >> > > > > > - pci_lock_rescan_remove(); >> > > > > > - list_for_each_entry_safe_reverse(dev, temp, &parent->devices, >> > > > > > - bus_list) { >> > > > > > - pci_dev_get(dev); >> > > > > > - pci_dev_set_disconnected(dev, NULL); >> > > > > > - if (pci_has_subordinate(dev)) >> > > > > > - pci_walk_bus(dev->subordinate, >> > > > > > - pci_dev_set_disconnected, NULL); >> > > > > > - pci_stop_and_remove_bus_device(dev); >> > > > > > - pci_dev_put(dev); >> > > > > > - } >> > > > > > - pci_unlock_rescan_remove(); >> > > > > > - >> > > > > > + struct dpc_dev *dpc; >> > > > > > + struct pcie_device *pciedev; >> > > > > > + struct device *devdpc; >> > > > > > + u16 cap, ctl; >> > > > > > + >> > > > > > + /* >> > > > > > + * DPC disables the Link automatically in hardware, so it has >> > > > > > + * already been reset by the time we get here. >> > > > > > + */ >> > > > > > + >> > > > > > + devdpc = pcie_port_find_device(pdev, PCIE_PORT_SERVICE_DPC); >> > > > > > + pciedev = to_pcie_device(devdpc); >> > > > > > + dpc = get_service_data(pciedev); >> > > > > > + cap = dpc->cap_pos; >> > > > > > + >> > > > > > + /* >> > > > > > + * Waiting until the link is inactive, then clearing DPC >> > > > > > + * trigger status to allow the port to leave DPC. >> > > > > > + */ >> > > > > > dpc_wait_link_inactive(dpc); >> > > > > > + >> > > > > > if (dpc->rp_extensions && dpc_wait_rp_inactive(dpc)) >> > > > > > - return; >> > > > > > + return PCI_ERS_RESULT_DISCONNECT; >> > > > > > if (dpc->rp_extensions && dpc->rp_pio_status) { >> > > > > > pci_write_config_dword(pdev, cap + PCI_EXP_DPC_RP_PIO_STATUS, >> > > > > > dpc->rp_pio_status); >> > > > > > @@ -108,6 +110,17 @@ static void dpc_work(struct work_struct *work) >> > > > > > pci_read_config_word(pdev, cap + PCI_EXP_DPC_CTL, &ctl); >> > > > > > pci_write_config_word(pdev, cap + PCI_EXP_DPC_CTL, >> > > > > > ctl | PCI_EXP_DPC_CTL_INT_EN); >> > > > > > + >> > > > > > + return PCI_ERS_RESULT_RECOVERED; >> > > > > > +} >> > > > > > + >> > > > > > +static void dpc_work(struct work_struct *work) >> > > > > > +{ >> > > > > > + struct dpc_dev *dpc = container_of(work, struct dpc_dev, work); >> > > > > > + struct pci_dev *pdev = dpc->dev->port; >> > > > > > + >> > > > > > + /* From DPC point of view error is always FATAL. */ >> > > > > > + pcie_do_fatal_recovery(pdev, PCIE_PORT_SERVICE_DPC); >> > > > > > } >> > > > > > >> > > > > > static void dpc_process_rp_pio_error(struct dpc_dev *dpc) >> > > > > > @@ -288,6 +301,7 @@ static struct pcie_port_service_driver dpcdriver = { >> > > > > > .service = PCIE_PORT_SERVICE_DPC, >> > > > > > .probe = dpc_probe, >> > > > > > .remove = dpc_remove, >> > > > > > + .reset_link = dpc_reset_link, >> > > > > > }; >> > > > > > >> > > > > > static int __init dpc_service_init(void) >> > > > > > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c >> > > > > > index 33a16b1..29ff148 100644 >> > > > > > --- a/drivers/pci/pcie/err.c >> > > > > > +++ b/drivers/pci/pcie/err.c >> > > > > > @@ -185,7 +185,7 @@ static pci_ers_result_t default_reset_link(struct >> > > > > > pci_dev *dev) >> > > > > > return PCI_ERS_RESULT_RECOVERED; >> > > > > > } >> > > > > > >> > > > > > -static pci_ers_result_t reset_link(struct pci_dev *dev) >> > > > > > +static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service) >> > > > > > { >> > > > > > struct pci_dev *udev; >> > > > > > pci_ers_result_t status; >> > > > > > @@ -200,7 +200,7 @@ static pci_ers_result_t reset_link(struct pci_dev >> > > > > > *dev) >> > > > > > } >> > > > > > >> > > > > > /* Use the aer driver of the component firstly */ >> > > > > > - driver = pcie_port_find_service(udev, PCIE_PORT_SERVICE_AER); >> > > > > > + driver = pcie_port_find_service(udev, service); >> > > > > > >> > > > > > if (driver && driver->reset_link) { >> > > > > > status = driver->reset_link(udev); >> > > > > > @@ -287,7 +287,7 @@ static pci_ers_result_t >> > > > > > broadcast_error_message(struct pci_dev *dev, >> > > > > > * followed by re-enumeration of devices. >> > > > > > */ >> > > > > > >> > > > > > -void pcie_do_fatal_recovery(struct pci_dev *dev) >> > > > > > +void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service) >> > > > > > { >> > > > > > struct pci_dev *udev; >> > > > > > struct pci_bus *parent; >> > > > > > @@ -313,7 +313,7 @@ void pcie_do_fatal_recovery(struct pci_dev *dev) >> > > > > > pci_dev_put(pdev); >> > > > > > } >> > > > > > >> > > > > > - result = reset_link(udev); >> > > > > > + result = reset_link(udev, service); >> > > > > > >> > > > > > if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >> > > > > > /* >> > > > > > diff --git a/include/linux/aer.h b/include/linux/aer.h >> > > > > > index 8f87bbe..0c506fe 100644 >> > > > > > --- a/include/linux/aer.h >> > > > > > +++ b/include/linux/aer.h >> > > > > > @@ -14,6 +14,7 @@ >> > > > > > #define AER_NONFATAL 0 >> > > > > > #define AER_FATAL 1 >> > > > > > #define AER_CORRECTABLE 2 >> > > > > > +#define DPC_FATAL 4 >> > > > >> > > > I think DPC_FATAL can be 3, since these values are not used as a bit >> > > > mask. >> > > > >> > > > > > struct pci_dev; >> > > > > >> > > > > >> > > > > Hi Bjorn, >> > > > > >> > > > > >> > > > > I have addressed all the comments, and I hope we are heading towards >> > > > > closure. >> > > > > >> > > > > I just figure that pcie_do_fatal_recovery (which is getting >> > > > > executed for >> > > > > DPC as well) >> > > > > >> > > > > if (result == PCI_ERS_RESULT_RECOVERED) { >> > > > > if (pcie_wait_for_link(udev, true)) >> > > > > pci_rescan_bus(udev->bus); >> > > > > pci_info(dev, "Device recovery successful\n"); >> > > > > } >> > > > > >> > > > > I have to correct it to >> > > > > >> > > > > if (service==AER && result == PCI_ERS_RESULT_RECOVERED) { >> > > > > if (pcie_wait_for_link(udev, true)) >> > > > > pci_rescan_bus(udev->bus); >> > > > > pci_info(dev, "Device recovery successful\n"); >> > > > > } >> > > > >> > > > This patch is mostly a restructuring of DPC and doesn't really change >> > > > its >> > > > behavior. DPC didn't previously call pcie_wait_for_link() or >> > > > pci_rescan_bus(), so I agree that adding the "service==AER" test will >> > > > help preserve the existing DPC behavior. >> > > > >> > > > However, the rescan should happen with DPC *somewhere* and we should >> > > > clarify where that is. Maybe for now we only need a comment about where >> > > > that happens. Ideally, we could eventually converge this so the same >> > > > mechanism is used for AER and DPC, so we wouldn't need a test like >> > > > "service=AER". >> > >> > Please still add a comment here about why the rescan behavior is >> > different. >> > >> > > I am sorry I pasted the wrong snippet. >> > > following needs to be fixed in v17. >> > > from: >> > > if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >> > > /* >> > > * If the error is reported by a bridge, we think >> > > this error >> > > * is related to the downstream link of the bridge, >> > > so we >> > > * do error recovery on all subordinates of the bridge >> > > instead >> > > * of the bridge and clear the error status of the >> > > bridge. >> > > */ >> > > pci_walk_bus(dev->subordinate, report_resume, >> > > &result_data); >> > > pci_cleanup_aer_uncorrect_error_status(dev); >> > > } >> > > >> > > >> > > to >> > > >> > > if (service==AER && dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >> > > /* >> > > * If the error is reported by a bridge, we think >> > > this error >> > > * is related to the downstream link of the bridge, >> > > so we >> > > * do error recovery on all subordinates of the bridge >> > > instead >> > > * of the bridge and clear the error status of the >> > > bridge. >> > > */ >> > > pci_walk_bus(dev->subordinate, report_resume, >> > > &result_data); >> > > pci_cleanup_aer_uncorrect_error_status(dev); >> > > } >> > > >> > > this is only needed in case of AER. >> > >> > Oh, I missed this before. It makes sense to clear the AER status >> > here, but why do we need to call report_resume()? We just called all >> > the driver .remove() methods and detached the drivers from the >> > devices. So I don't think report_resume() will do anything >> > ("dev->driver" should be NULL) except set the dev->error_state to >> > pci_channel_io_normal. We probably don't need that because we didn't >> > change error_state in this fatal error path. >> >> if you remember, the path ends up calling >> aer_error_resume >> >> the existing code ends up calling aer_error_resume as follows. >> >> do_recovery(pci_dev) >> broadcast_error_message(..., error_detected, ...) >> if (AER_FATAL) >> reset_link(pci_dev) >> udev = BRIDGE ? pci_dev : pci_dev->bus->self >> driver->reset_link(udev) >> aer_root_reset(udev) >> if (CAN_RECOVER) >> broadcast_error_message(..., mmio_enabled, ...) >> if (NEED_RESET) >> broadcast_error_message(..., slot_reset, ...) >> broadcast_error_message(dev, ..., report_resume, ...) >> if (BRIDGE) >> report_resume >> driver->resume >> pcie_portdrv_err_resume >> device_for_each_child(..., resume_iter) >> resume_iter >> driver->error_resume >> aer_error_resume >> pci_cleanup_aer_uncorrect_error_status(pci_dev) # only >> if >> BRIDGE >> pci_write_config_dword(PCI_ERR_UNCOR_STATUS) >> >> hence I think we have to call it in order to clear the root port >> PCI_ERR_UNCOR_STATUS and PCI_EXP_DEVSTA. >> makes sense ? > > I know I sent you the call graph above, so you would think I might > understand it, but you would be mistaken :) This still doesn't make > sense to me. > > I think your point is that we need to call aer_error_resume(). That > is the aerdriver.error_resume() method. The AER driver only binds to > root ports. > > This path: > > pcie_do_fatal_recovery > pci_walk_bus(dev->subordinate, report_resume, &result_data) > > calls report_resume() for every device on the dev->subordinate bus > (and for anything below those devices). There are no root ports on > that dev->subordinate bus, because root ports are always on a root > bus, never on a subordinate bus. > > So I don't see how report_resume() can ever get to aer_error_resume(). > Can you instrument that path and verify that it actually does get > there somehow?
you are right....the call pci_walk_bus(dev->subordinate, report_resume, &result_data); does not call aer_error_resume()
but pci_walk_bus(udev->bus, report_resume, &result_data); does call aer_error_resume()
now if you look at the comment of the function: /** * aer_error_resume - clean up corresponding error status bits * @dev: pointer to Root Port's pci_dev data structure * * Invoked by Port Bus driver during nonfatal recovery. */
it is invoked during nonfatal recovery. but the code handles both fatal and nonfatal clearing of error bits.
if (dev->error_state == pci_channel_io_normal) status &= ~mask; /* Clear corresponding nonfatal bits */ else status &= mask; /* Clear corresponding fatal bits */ pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);
so the question is, should we not call aer_error_resume during fatal recovery ? so that it clears the root port status, if of course the error is triggered by AER running agent (RP, Switch)
Regards, Oza.
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