Re: [PATCH v2 07/13] powerpc/eeh: Clean up pci_ers_result handling

[Sam Bobroff <sbobroff@linux.ibm.com>]

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On Sat, Jun 02, 2018 at 01:40:46AM +1000, Michael Ellerman wrote:
> Sam Bobroff <sbobroff@linux.ibm.com> writes:
> 
> > As EEH event handling progresses, a cumulative result of type
> > pci_ers_result is built up by (some of) the eeh_report_*() functions
> > using either:
> > 	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
> > 	if (*res == PCI_ERS_RESULT_NONE) *res = rc;
> > or:
> > 	if ((*res == PCI_ERS_RESULT_NONE) ||
> > 	    (*res == PCI_ERS_RESULT_RECOVERED)) *res = rc;
> > 	if (*res == PCI_ERS_RESULT_DISCONNECT &&
> > 	    rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
> > (Where *res is the accumulator.)
> >
> > However, the intent is not immediately clear and the result in some
> > situations is order dependent.
> >
> > Address this by assigning a priority to each result value, and always
> > merging to the highest priority. This renders the intent clear, and
> > provides a stable value for all orderings.
> >
> > Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
> > ---
> > ====== v1 -> v2: ======
> >
> > * Added the value, and missing newline, to some WARN()s.
> > * Improved name of merge_result() to pci_ers_merge_result().
> > * Adjusted the result priorities so that unknown doesn't overlap with _NONE.
> 
> These === markers seem to have confused patchwork, they ended up in the
> patch, and then git put them in the changelog.
> 
> http://patchwork.ozlabs.org/patch/920194/
> 
> The usual format is just something like:
> 
> v2 - Added the value, and missing newline, to some WARN()s.
>    - Improved name of merge_result() to pci_ers_merge_result().
>    - Adjusted the result priorities so that unknown doesn't overlap with _NONE.
> 
> cheers

Oh! I'll change it!

Sam.

> 
> >  arch/powerpc/kernel/eeh_driver.c | 36 ++++++++++++++++++++++++++----------
> >  1 file changed, 26 insertions(+), 10 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
> > index 188d15c4fe3a..2d3cac584899 100644
> > --- a/arch/powerpc/kernel/eeh_driver.c
> > +++ b/arch/powerpc/kernel/eeh_driver.c
> > @@ -39,6 +39,29 @@ struct eeh_rmv_data {
> >  	int removed;
> >  };
> >  
> > +static int eeh_result_priority(enum pci_ers_result result)
> > +{
> > +	switch (result) {
> > +	case PCI_ERS_RESULT_NONE: return 1;
> > +	case PCI_ERS_RESULT_NO_AER_DRIVER: return 2;
> > +	case PCI_ERS_RESULT_RECOVERED: return 3;
> > +	case PCI_ERS_RESULT_CAN_RECOVER: return 4;
> > +	case PCI_ERS_RESULT_DISCONNECT: return 5;
> > +	case PCI_ERS_RESULT_NEED_RESET: return 6;
> > +	default:
> > +		WARN_ONCE(1, "Unknown pci_ers_result value: %d\n", (int)result);
> > +		return 0;
> > +	}
> > +};
> > +
> > +static enum pci_ers_result pci_ers_merge_result(enum pci_ers_result old,
> > +						enum pci_ers_result new)
> > +{
> > +	if (eeh_result_priority(new) > eeh_result_priority(old))
> > +		return new;
> > +	return old;
> > +}
> > +
> >  /**
> >   * eeh_pcid_get - Get the PCI device driver
> >   * @pdev: PCI device
> > @@ -206,9 +229,7 @@ static void *eeh_report_error(struct eeh_dev *edev, void *userdata)
> >  
> >  	rc = driver->err_handler->error_detected(dev, pci_channel_io_frozen);
> >  
> > -	/* A driver that needs a reset trumps all others */
> > -	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
> > -	if (*res == PCI_ERS_RESULT_NONE) *res = rc;
> > +	*res = pci_ers_merge_result(*res, rc);
> >  
> >  	edev->in_error = true;
> >  	pci_uevent_ers(dev, PCI_ERS_RESULT_NONE);
> > @@ -249,9 +270,7 @@ static void *eeh_report_mmio_enabled(struct eeh_dev *edev, void *userdata)
> >  
> >  	rc = driver->err_handler->mmio_enabled(dev);
> >  
> > -	/* A driver that needs a reset trumps all others */
> > -	if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
> > -	if (*res == PCI_ERS_RESULT_NONE) *res = rc;
> > +	*res = pci_ers_merge_result(*res, rc);
> >  
> >  out:
> >  	eeh_pcid_put(dev);
> > @@ -294,10 +313,7 @@ static void *eeh_report_reset(struct eeh_dev *edev, void *userdata)
> >  		goto out;
> >  
> >  	rc = driver->err_handler->slot_reset(dev);
> > -	if ((*res == PCI_ERS_RESULT_NONE) ||
> > -	    (*res == PCI_ERS_RESULT_RECOVERED)) *res = rc;
> > -	if (*res == PCI_ERS_RESULT_DISCONNECT &&
> > -	     rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
> > +	*res = pci_ers_merge_result(*res, rc);
> >  
> >  out:
> >  	eeh_pcid_put(dev);
> > -- 
> > 2.16.1.74.g9b0b1f47b
> 

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