linux-kernel - Re: [PATCH] Documentation: PCI: pci-error-recovery: rearrange the general sequence

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Message-ID: <20210702024123.GA2714@buildhost>
Date:   Fri, 2 Jul 2021 10:41:23 +0800
From:   Wesley Sheng <wesley.sheng@....com>
To:     linasvepstas@...il.com, ruscur@...sell.cc, oohall@...il.com,
        bhelgaas@...gle.com, corbet@....net, linux-pci@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     wesleyshenggit@...a.com
Subject: Re: [PATCH] Documentation: PCI: pci-error-recovery: rearrange the
 general sequence

On Thu, Jul 01, 2021 at 05:22:31PM -0500, Bjorn Helgaas wrote:
> Please make the subject a little more specific.  "rearrange the
> general sequence" doesn't say anything about what was affected.
> 
> On Fri, Jun 18, 2021 at 02:04:46PM +0800, Wesley Sheng wrote:
> > Reset_link() callback function was called before mmio_enabled() in
> > pcie_do_recovery() function actually, so rearrange the general
> > sequence betwen step 2 and step 3 accordingly.
> 
> s/betwen/between/
> 
> Not sure "general" adds anything in this sentence.  "Step 2 and step
> 3" are not meaningful here in the commit log.  It needs to spell out
> what those steps are so the log makes sense by itself.
> 
> "reset_link" does not appear in pcie_do_recovery().  I'm guessing
> you're referring to the "reset_subordinates" function pointer?
>
Yes, you are right.
pcieaer-howto.rst has a section named with "Provide callbacks",
the callback supplied to pcie_do_recovery() was referred to 
reset_link.
 
> > Signed-off-by: Wesley Sheng <wesley.sheng@....com>
> 
> I didn't quite understand your response to Oliver, so I'll wait for
> your corrections and his ack before proceeding.
>
OK.
I thought step 2 MMIO Enabled and step 3 link reset should swap sequence.

> > ---
> >  Documentation/PCI/pci-error-recovery.rst | 23 ++++++++++++-----------
> >  1 file changed, 12 insertions(+), 11 deletions(-)
> > 
> > diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI/pci-error-recovery.rst
> > index 187f43a03200..ac6a8729ef28 100644
> > --- a/Documentation/PCI/pci-error-recovery.rst
> > +++ b/Documentation/PCI/pci-error-recovery.rst
> > @@ -184,7 +184,14 @@ is STEP 6 (Permanent Failure).
> >     and prints an error to syslog.  A reboot is then required to
> >     get the device working again.
> >  
> > -STEP 2: MMIO Enabled
> > +STEP 2: Link Reset
> > +------------------
> > +The platform resets the link.  This is a PCI-Express specific step
> > +and is done whenever a fatal error has been detected that can be
> > +"solved" by resetting the link.
> > +
> > +
> > +STEP 3: 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
> > @@ -197,8 +204,8 @@ information, if any, and eventually do things like trigger a device local
> >  reset or some such, but not restart operations. This callback is made if
> >  all drivers on a segment agree that they can try to recover and if no automatic
> >  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)
> > +without a slot reset, it will not call this callback, and
> > +instead will have gone directly or STEP 4 (Slot Reset)
> 
> s/or/to/  ?
> 
> >  .. note::
> >  
> > @@ -210,7 +217,7 @@ instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset)
> >     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.
> > +   into next states, that is, slot reset.
> 
> s/into next states/into the next state/ ?
> 
> >  The driver should return one of the following result codes:
> >    - PCI_ERS_RESULT_RECOVERED
> > @@ -233,17 +240,11 @@ The driver should return one of the following result codes:
> >  
> >  The next step taken depends on the results returned by the drivers.
> >  If all drivers returned PCI_ERS_RESULT_RECOVERED, then the platform
> > -proceeds to either STEP3 (Link Reset) or to STEP 5 (Resume Operations).
> > +proceeds to STEP 5 (Resume Operations).
> >  
> >  If any driver returned PCI_ERS_RESULT_NEED_RESET, then the platform
> >  proceeds to STEP 4 (Slot Reset)
> >  
> > -STEP 3: Link Reset
> > -------------------
> > -The platform resets the link.  This is a PCI-Express specific step
> > -and is done whenever a fatal error has been detected that can be
> > -"solved" by resetting the link.
> > -
> >  STEP 4: Slot Reset
> >  ------------------
> >  
> > -- 
> > 2.25.1
> >