linux-kernel - Re: [PATCH 03/11] cxl/mem: Implement Clear Event Records command

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Date:   Wed, 16 Nov 2022 15:45:43 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     <ira.weiny@...el.com>
CC:     Dan Williams <dan.j.williams@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "Ben Widawsky" <bwidawsk@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        <linux-kernel@...r.kernel.org>, <linux-cxl@...r.kernel.org>
Subject: Re: [PATCH 03/11] cxl/mem: Implement Clear Event Records command

On Wed, 16 Nov 2022 15:24:26 +0000
Jonathan Cameron <Jonathan.Cameron@...wei.com> wrote:

> On Thu, 10 Nov 2022 10:57:50 -0800
> ira.weiny@...el.com wrote:
> 
> > From: Ira Weiny <ira.weiny@...el.com>
> > 
> > CXL rev 3.0 section 8.2.9.2.3 defines the Clear Event Records mailbox
> > command.  After an event record is read it needs to be cleared from the
> > event log.
> > 
> > Implement cxl_clear_event_record() and call it for each record retrieved
> > from the device.
> > 
> > Each record is cleared individually.  A clear all bit is specified but
> > events could arrive between a get and the final clear all operation.
> > Therefore each event is cleared specifically.
> > 
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> >   
> Some follow through comment updates needed from changes in earlier patches +
> one comment you can ignore if you prefer to keep it as is.
> 
> >  static void cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
> >  				    enum cxl_event_log_type type)
> >  {
> > @@ -728,14 +750,23 @@ static void cxl_mem_get_records_log(struct cxl_dev_state *cxlds,
> >  		}
> >  
> >  		pl_nr = le16_to_cpu(payload.record_count);
> > -		if (trace_cxl_generic_event_enabled()) {  
> 
> To simplify this patch, maybe push this check down in the previous patch so this
> one doesn't move code around?  It'll look a tiny bit odd there of course..
> 
> > +		if (pl_nr > 0) {
> >  			u16 nr_rec = min_t(u16, pl_nr, CXL_GET_EVENT_NR_RECORDS);
> >  			int i;
> >  
> > -			for (i = 0; i < nr_rec; i++)
> > -				trace_cxl_generic_event(dev_name(cxlds->dev),
> > -							type,
> > -							&payload.record[i]);
> > +			if (trace_cxl_generic_event_enabled()) {
> > +				for (i = 0; i < nr_rec; i++)
> > +					trace_cxl_generic_event(dev_name(cxlds->dev),
> > +								type,
> > +								&payload.record[i]);
> > +			}
> > +
> > +			rc = cxl_clear_event_record(cxlds, type, &payload, nr_rec);
> > +			if (rc) {
> > +				dev_err(cxlds->dev, "Event log '%s': Failed to clear events : %d",
> > +					cxl_event_log_type_str(type), rc);
> > +				return;
> > +			}
> >  		}
> >    
> 
> > diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> > index da64ba0f156b..28a114c7cf69 100644
> > --- a/drivers/cxl/cxlmem.h
> > +++ b/drivers/cxl/cxlmem.h  
> 
> >  
> > +/*
> > + * Clear Event Records input payload
> > + * CXL rev 3.0 section 8.2.9.2.3; Table 8-51
> > + *
> > + * Space given for 1 record  
> 
> Nope...
> 
> 
> > + */
> > +struct cxl_mbox_clear_event_payload {
> > +	u8 event_log;		/* enum cxl_event_log_type */
> > +	u8 clear_flags;
> > +	u8 nr_recs;		/* 1 for this struct */  
> Nope :)  Delete the comments so they can't be wrong if this changes in future!
Ah. You only use one. So should hard code that in the array size below.

> 
> > +	u8 reserved[3];
> > +	__le16 handle[CXL_GET_EVENT_NR_RECORDS];
> > +};
> > +  
>