Re: [PATCH v5 07/12] Documentation: PCI: convert pci-error-recovery.txt to reST

Mauro Carvalho Chehab
2019-05-13T14:56:16Z

Em Mon, 13 May 2019 22:19:55 +0800
Changbin Du <changbin.du@gmail.com> escreveu:

> This converts the plain text documentation to reStructuredText format and
> add it to Sphinx TOC tree. No essential content change.
>
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

> ---
> Documentation/PCI/index.rst | 1 +
> ...or-recovery.txt => pci-error-recovery.rst} | 287 +++++++++---------
> MAINTAINERS | 4 +-
> 3 files changed, 152 insertions(+), 140 deletions(-)
> rename Documentation/PCI/{pci-error-recovery.txt => pci-error-recovery.rst} (67%)
>
> diff --git a/Documentation/PCI/index.rst b/Documentation/PCI/index.rst
> index 6f573f3df993..92e62d0fc9e6 100644
> --- a/Documentation/PCI/index.rst
> +++ b/Documentation/PCI/index.rst
> @@ -13,3 +13,4 @@ Linux PCI Bus Subsystem
> pci-iov-howto
> msi-howto
> acpi-info
> + pci-error-recovery
> diff --git a/Documentation/PCI/pci-error-recovery.txt b/Documentation/PCI/pci-error-recovery.rst
> similarity index 67%
> rename from Documentation/PCI/pci-error-recovery.txt
> rename to Documentation/PCI/pci-error-recovery.rst
> index 0b6bb3ef449e..83db42092935 100644
> --- a/Documentation/PCI/pci-error-recovery.txt
> +++ b/Documentation/PCI/pci-error-recovery.rst
> @@ -1,12 +1,13 @@
> +.. SPDX-License-Identifier: GPL-2.0
>
> - PCI Error Recovery
> - ------------------
> - February 2, 2006
> +==================
> +PCI Error Recovery
> +==================
>
> - Current document maintainer:
> - Linas Vepstas <linasvepstas@gmail.com>
> - updated by Richard Lary <rlary@us.ibm.com>
> - and Mike Mason <mmlnx@us.ibm.com> on 27-Jul-2009
> +
> +:Authors: - Linas Vepstas <linasvepstas@gmail.com>
> + - Richard Lary <rlary@us.ibm.com>
> + - Mike Mason <mmlnx@us.ibm.com>
>
>
> Many PCI bus controllers are able to detect a variety of hardware
> @@ -63,7 +64,8 @@ mechanisms for dealing with SCSI bus errors and SCSI bus resets.
>
>
> Detailed Design
> ----------------
> +===============
> +
> Design and implementation details below, based on a chain of
> public email discussions with Ben Herrenschmidt, circa 5 April 2005.
>
> @@ -73,30 +75,33 @@ pci_driver. A driver that fails to provide the structure is "non-aware",
> and the actual recovery steps taken are platform dependent. The
> arch/powerpc implementation will simulate a PCI hotplug remove/add.
>
> -This structure has the form:
> -struct pci_error_handlers
> -{
> - int (*error_detected)(struct pci_dev *dev, enum pci_channel_state);
> - int (*mmio_enabled)(struct pci_dev *dev);
> - int (*slot_reset)(struct pci_dev *dev);
> - void (*resume)(struct pci_dev *dev);
> -};
> -
> -The possible channel states are:
> -enum pci_channel_state {
> - pci_channel_io_normal, /* I/O channel is in normal state */
> - pci_channel_io_frozen, /* I/O to channel is blocked */
> - pci_channel_io_perm_failure, /* PCI card is dead */
> -};
> -
> -Possible return values are:
> -enum pci_ers_result {
> - PCI_ERS_RESULT_NONE, /* no result/none/not supported in device driver */
> - PCI_ERS_RESULT_CAN_RECOVER, /* Device driver can recover without slot reset */
> - PCI_ERS_RESULT_NEED_RESET, /* Device driver wants slot to be reset. */
> - PCI_ERS_RESULT_DISCONNECT, /* Device has completely failed, is unrecoverable */
> - PCI_ERS_RESULT_RECOVERED, /* Device driver is fully recovered and operational */
> -};
> +This structure has the form::
> +
> + struct pci_error_handlers
> + {
> + int (*error_detected)(struct pci_dev *dev, enum pci_channel_state);
> + int (*mmio_enabled)(struct pci_dev *dev);
> + int (*slot_reset)(struct pci_dev *dev);
> + void (*resume)(struct pci_dev *dev);
> + };
> +
> +The possible channel states are::
> +
> + enum pci_channel_state {
> + pci_channel_io_normal, /* I/O channel is in normal state */
> + pci_channel_io_frozen, /* I/O to channel is blocked */
> + pci_channel_io_perm_failure, /* PCI card is dead */
> + };
> +
> +Possible return values are::
> +
> + enum pci_ers_result {
> + PCI_ERS_RESULT_NONE, /* no result/none/not supported in device driver */
> + PCI_ERS_RESULT_CAN_RECOVER, /* Device driver can recover without slot reset */
> + PCI_ERS_RESULT_NEED_RESET, /* Device driver wants slot to be reset. */
> + PCI_ERS_RESULT_DISCONNECT, /* Device has completely failed, is unrecoverable */
> + PCI_ERS_RESULT_RECOVERED, /* Device driver is fully recovered and operational */
> + };
>
> A driver does not have to implement all of these callbacks; however,
> if it implements any, it must implement error_detected(). If a callback
> @@ -134,16 +139,17 @@ shouldn't do any new IOs. Called in task context. This is sort of a
>
> All drivers participating in this system must implement this call.
> The driver must return one of the following result codes:
> - - PCI_ERS_RESULT_CAN_RECOVER:
> - Driver returns this if it thinks it might be able to recover
> - the HW by just banging IOs or if it wants to be given
> - a chance to extract some diagnostic information (see
> - mmio_enable, below).
> - - PCI_ERS_RESULT_NEED_RESET:
> - Driver returns this if it can't recover without a
> - slot reset.
> - - PCI_ERS_RESULT_DISCONNECT:
> - Driver returns this if it doesn't want to recover at all.
> +
> + - PCI_ERS_RESULT_CAN_RECOVER
> + Driver returns this if it thinks it might be able to recover
> + the HW by just banging IOs or if it wants to be given
> + a chance to extract some diagnostic information (see
> + mmio_enable, below).
> + - PCI_ERS_RESULT_NEED_RESET
> + Driver returns this if it can't recover without a
> + slot reset.
> + - PCI_ERS_RESULT_DISCONNECT
> + Driver returns this if it doesn't want to recover at all.
>
> The next step taken will depend on the result codes returned by the
> drivers.
> @@ -159,25 +165,27 @@ then recovery proceeds to STEP 4 (Slot Reset).
> If the platform is unable to recover the slot, the next step
> is STEP 6 (Permanent Failure).
>
> ->>> The current powerpc implementation assumes that a device driver will
> ->>> *not* schedule or semaphore in this routine; the current powerpc
> ->>> implementation uses one kernel thread to notify all devices;
> ->>> thus, if one device sleeps/schedules, all devices are affected.
> ->>> Doing better requires complex multi-threaded logic in the error
> ->>> recovery implementation (e.g. waiting for all notification threads
> ->>> to "join" before proceeding with recovery.) This seems excessively
> ->>> complex and not worth implementing.
> -
> ->>> The current powerpc implementation doesn't much care if the device
> ->>> attempts I/O at this point, or not. I/O's will fail, returning
> ->>> a value of 0xff on read, and writes will be dropped. If more than
> ->>> EEH_MAX_FAILS I/O's are attempted to a frozen adapter, EEH
> ->>> assumes that the device driver has gone into an infinite loop
> ->>> and prints an error to syslog. A reboot is then required to
> ->>> get the device working again.
> +.. note::
> +
> + The current powerpc implementation assumes that a device driver will
> + *not* schedule or semaphore in this routine; the current powerpc
> + implementation uses one kernel thread to notify all devices;
> + thus, if one device sleeps/schedules, all devices are affected.
> + Doing better requires complex multi-threaded logic in the error
> + recovery implementation (e.g. waiting for all notification threads
> + to "join" before proceeding with recovery.) This seems excessively
> + complex and not worth implementing.
> +
> + The current powerpc implementation doesn't much care if the device
> + attempts I/O at this point, or not. I/O's will fail, returning
> + a value of 0xff on read, and writes will be dropped. If more than
> + EEH_MAX_FAILS I/O's are attempted to a frozen adapter, EEH
> + assumes that the device driver has gone into an infinite loop
> + and prints an error to syslog. A reboot is then required to
> + get the device working again.
>
> STEP 2: MMIO Enabled
> --------------------
> +--------------------
> The platform re-enables MMIO to the device (but typically not the
> DMA), and then calls the mmio_enabled() callback on all affected
> device drivers.
> @@ -192,34 +200,36 @@ link reset was performed by the HW. If the platform can't just re-enable IOs
> without a slot reset or a link reset, it will not call this callback, and
> instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset)
>
> ->>> The following is proposed; no platform implements this yet:
> ->>> Proposal: All I/O's should be done _synchronously_ from within
> ->>> this callback, errors triggered by them will be returned via
> ->>> the normal pci_check_whatever() API, no new error_detected()
> ->>> callback will be issued due to an error happening here. However,
> ->>> such an error might cause IOs to be re-blocked for the whole
> ->>> segment, and thus invalidate the recovery that other devices
> ->>> on the same segment might have done, forcing the whole segment
> ->>> into one of the next states, that is, link reset or slot reset.
> +.. note::
> +
> + The following is proposed; no platform implements this yet:
> + Proposal: All I/O's should be done _synchronously_ from within
> + this callback, errors triggered by them will be returned via
> + the normal pci_check_whatever() API, no new error_detected()
> + callback will be issued due to an error happening here. However,
> + such an error might cause IOs to be re-blocked for the whole
> + segment, and thus invalidate the recovery that other devices
> + on the same segment might have done, forcing the whole segment
> + into one of the next states, that is, link reset or slot reset.
>
> The driver should return one of the following result codes:
> - - PCI_ERS_RESULT_RECOVERED
> - Driver returns this if it thinks the device is fully
> - functional and thinks it is ready to start
> - normal driver operations again. There is no
> - guarantee that the driver will actually be
> - allowed to proceed, as another driver on the
> - same segment might have failed and thus triggered a
> - slot reset on platforms that support it.
> -
> - - PCI_ERS_RESULT_NEED_RESET
> - Driver returns this if it thinks the device is not
> - recoverable in its current state and it needs a slot
> - reset to proceed.
> -
> - - PCI_ERS_RESULT_DISCONNECT
> - Same as above. Total failure, no recovery even after
> - reset driver dead. (To be defined more precisely)
> + - PCI_ERS_RESULT_RECOVERED
> + Driver returns this if it thinks the device is fully
> + functional and thinks it is ready to start
> + normal driver operations again. There is no
> + guarantee that the driver will actually be
> + allowed to proceed, as another driver on the
> + same segment might have failed and thus triggered a
> + slot reset on platforms that support it.
> +
> + - PCI_ERS_RESULT_NEED_RESET
> + Driver returns this if it thinks the device is not
> + recoverable in its current state and it needs a slot
> + reset to proceed.
> +
> + - PCI_ERS_RESULT_DISCONNECT
> + Same as above. Total failure, no recovery even after
> + reset driver dead. (To be defined more precisely)
>
> The next step taken depends on the results returned by the drivers.
> If all drivers returned PCI_ERS_RESULT_RECOVERED, then the platform
> @@ -293,31 +303,33 @@ device will be considered "dead" in this case.
> Drivers for multi-function cards will need to coordinate among
> themselves as to which driver instance will perform any "one-shot"
> or global device initialization. For example, the Symbios sym53cxx2
> -driver performs device init only from PCI function 0:
> +driver performs device init only from PCI function 0::
>
> -+ if (PCI_FUNC(pdev->devfn) == 0)
> -+ sym_reset_scsi_bus(np, 0);
> + + if (PCI_FUNC(pdev->devfn) == 0)
> + + sym_reset_scsi_bus(np, 0);
>
> - Result codes:
> - - PCI_ERS_RESULT_DISCONNECT
> - Same as above.
> +Result codes:
> + - PCI_ERS_RESULT_DISCONNECT
> + Same as above.
>
> Drivers for PCI Express cards that require a fundamental reset must
> set the needs_freset bit in the pci_dev structure in their probe function.
> For example, the QLogic qla2xxx driver sets the needs_freset bit for certain
> -PCI card types:
> +PCI card types::
>
> -+ /* Set EEH reset type to fundamental if required by hba */
> -+ if (IS_QLA24XX(ha) || IS_QLA25XX(ha) || IS_QLA81XX(ha))
> -+ pdev->needs_freset = 1;
> -+
> + + /* Set EEH reset type to fundamental if required by hba */
> + + if (IS_QLA24XX(ha) || IS_QLA25XX(ha) || IS_QLA81XX(ha))
> + + pdev->needs_freset = 1;
> + +
>
> Platform proceeds either to STEP 5 (Resume Operations) or STEP 6 (Permanent
> Failure).
>
> ->>> The current powerpc implementation does not try a power-cycle
> ->>> reset if the driver returned PCI_ERS_RESULT_DISCONNECT.
> ->>> However, it probably should.
> +.. note::
> +
> + The current powerpc implementation does not try a power-cycle
> + reset if the driver returned PCI_ERS_RESULT_DISCONNECT.
> + However, it probably should.
>
>
> STEP 5: Resume Operations
> @@ -370,44 +382,43 @@ The current policy is to turn this into a platform policy.
> That is, the recovery API only requires that:
>
> - There is no guarantee that interrupt delivery can proceed from any
> -device on the segment starting from the error detection and until the
> -slot_reset callback is called, at which point interrupts are expected
> -to be fully operational.
> + device on the segment starting from the error detection and until the
> + slot_reset callback is called, at which point interrupts are expected
> + to be fully operational.
>
> - There is no guarantee that interrupt delivery is stopped, that is,
> -a driver that gets an interrupt after detecting an error, or that detects
> -an error within the interrupt handler such that it prevents proper
> -ack'ing of the interrupt (and thus removal of the source) should just
> -return IRQ_NOTHANDLED. It's up to the platform to deal with that
> -condition, typically by masking the IRQ source during the duration of
> -the error handling. It is expected that the platform "knows" which
> -interrupts are routed to error-management capable slots and can deal
> -with temporarily disabling that IRQ number during error processing (this
> -isn't terribly complex). That means some IRQ latency for other devices
> -sharing the interrupt, but there is simply no other way. High end
> -platforms aren't supposed to share interrupts between many devices
> -anyway :)
> -
> ->>> Implementation details for the powerpc platform are discussed in
> ->>> the file Documentation/powerpc/eeh-pci-error-recovery.txt
> -
> ->>> As of this writing, there is a growing list of device drivers with
> ->>> patches implementing error recovery. Not all of these patches are in
> ->>> mainline yet. These may be used as "examples":
> ->>>
> ->>> drivers/scsi/ipr
> ->>> drivers/scsi/sym53c8xx_2
> ->>> drivers/scsi/qla2xxx
> ->>> drivers/scsi/lpfc
> ->>> drivers/next/bnx2.c
> ->>> drivers/next/e100.c
> ->>> drivers/net/e1000
> ->>> drivers/net/e1000e
> ->>> drivers/net/ixgb
> ->>> drivers/net/ixgbe
> ->>> drivers/net/cxgb3
> ->>> drivers/net/s2io.c
> ->>> drivers/net/qlge
> -
> -The End
> --------
> + a driver that gets an interrupt after detecting an error, or that detects
> + an error within the interrupt handler such that it prevents proper
> + ack'ing of the interrupt (and thus removal of the source) should just
> + return IRQ_NOTHANDLED. It's up to the platform to deal with that
> + condition, typically by masking the IRQ source during the duration of
> + the error handling. It is expected that the platform "knows" which
> + interrupts are routed to error-management capable slots and can deal
> + with temporarily disabling that IRQ number during error processing (this
> + isn't terribly complex). That means some IRQ latency for other devices
> + sharing the interrupt, but there is simply no other way. High end
> + platforms aren't supposed to share interrupts between many devices
> + anyway :)
> +
> +.. note::
> +
> + Implementation details for the powerpc platform are discussed in
> + the file Documentation/powerpc/eeh-pci-error-recovery.txt
> +
> + As of this writing, there is a growing list of device drivers with
> + patches implementing error recovery. Not all of these patches are in
> + mainline yet. These may be used as "examples":
> +
> + - drivers/scsi/ipr
> + - drivers/scsi/sym53c8xx_2
> + - drivers/scsi/qla2xxx
> + - drivers/scsi/lpfc
> + - drivers/next/bnx2.c
> + - drivers/next/e100.c
> + - drivers/net/e1000
> + - drivers/net/e1000e
> + - drivers/net/ixgb
> + - drivers/net/ixgbe
> + - drivers/net/cxgb3
> + - drivers/net/s2io.c
> + - drivers/net/qlge
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fb9f9d71f7a2..6e5ec5d3987e 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12101,7 +12101,7 @@ M: Sam Bobroff <sbobroff@linux.ibm.com>
> M: Oliver O'Halloran <oohall@gmail.com>
> L: linuxppc-dev@lists.ozlabs.org
> S: Supported
> -F: Documentation/PCI/pci-error-recovery.txt
> +F: Documentation/PCI/pci-error-recovery.rst
> F: drivers/pci/pcie/aer.c
> F: drivers/pci/pcie/dpc.c
> F: drivers/pci/pcie/err.c
> @@ -12114,7 +12114,7 @@ PCI ERROR RECOVERY
> M: Linas Vepstas <linasvepstas@gmail.com>
> L: linux-pci@vger.kernel.org
> S: Supported
> -F: Documentation/PCI/pci-error-recovery.txt
> +F: Documentation/PCI/pci-error-recovery.rst
>
> PCI MSI DRIVER FOR ALTERA MSI IP
> M: Ley Foon Tan <lftan@altera.com>

Thanks,
Mauro