linux-kernel - Re: [PATCH 01/13] edac: Create a dimm struct and move the labels into it

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Date:	Fri, 30 Mar 2012 12:50:48 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Mauro Carvalho Chehab <mchehab@...hat.com>
Cc:	Linux Edac Mailing List <linux-edac@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 01/13] edac: Create a dimm struct and move the labels
 into it

On Thu, Mar 29, 2012 at 01:45:34PM -0300, Mauro Carvalho Chehab wrote:
> The way a DIMM is currently represented implies that they're
> linked into a per-csrow struct. However, some drivers don't see
> csrows, as they're ridden behind some chip like the AMB's
> on FBDIMM's, for example.
> 
> This forced drivers to fake a csrow struct, and to create
> a mess under csrow/channel original's concept.
> 
> Move the DIMM labels into a per-DIMM struct, and add there
> the real location of the socket, in terms of csrow/channel.
> Latter patches will modify the location to properly represent the
> memory architecture.
> 
> All other drivers will use a per-csrow type of location.
> Some of those drivers will require a latter conversion, as
> they also fake the csrows internally.
> 
> TODO: While this patch doesn't change the existing behavior, on
> csrows-based memory controllers, a csrow/channel pair points to a memory
> rank. There's a known bug at the EDAC core that allows having different
> labels for the same DIMM, if it has more than one rank. A latter patch
> is need to merge the several ranks for a DIMM into the same dimm_info
> struct, in order to avoid having different labels for the same DIMM.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>
> ---
>  drivers/edac/edac_mc.c       |   50 +++++++++++++++++++++++++++++++----------
>  drivers/edac/edac_mc_sysfs.c |   11 ++++-----
>  drivers/edac/i5100_edac.c    |    8 +++---
>  drivers/edac/i7core_edac.c   |    4 +-
>  drivers/edac/i82975x_edac.c  |    2 +-
>  drivers/edac/sb_edac.c       |    4 +-
>  include/linux/edac.h         |   28 +++++++++++++++++++----
>  7 files changed, 75 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
> index 690cbf1..c03bfe7 100644
> --- a/drivers/edac/edac_mc.c
> +++ b/drivers/edac/edac_mc.c
> @@ -44,7 +44,7 @@ static void edac_mc_dump_channel(struct rank_info *chan)
>  	debugf4("\tchannel = %p\n", chan);
>  	debugf4("\tchannel->chan_idx = %d\n", chan->chan_idx);
>  	debugf4("\tchannel->ce_count = %d\n", chan->ce_count);
> -	debugf4("\tchannel->label = '%s'\n", chan->label);
> +	debugf4("\tchannel->label = '%s'\n", chan->dimm->label);
>  	debugf4("\tchannel->csrow = %p\n\n", chan->csrow);
>  }
>  
> @@ -157,6 +157,7 @@ struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
>  	struct mem_ctl_info *mci;
>  	struct csrow_info *csi, *csrow;
>  	struct rank_info *chi, *chp, *chan;
> +	struct dimm_info *dimm;
>  	void *pvt;
>  	unsigned size;
>  	int row, chn;
> @@ -170,7 +171,8 @@ struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
>  	mci = (struct mem_ctl_info *)0;
>  	csi = edac_align_ptr(&mci[1], sizeof(*csi));
>  	chi = edac_align_ptr(&csi[nr_csrows], sizeof(*chi));
> -	pvt = edac_align_ptr(&chi[nr_chans * nr_csrows], sz_pvt);
> +	dimm = edac_align_ptr(&chi[nr_chans * nr_csrows], sizeof(*dimm));
> +	pvt = edac_align_ptr(&dimm[nr_chans * nr_csrows], sz_pvt);
>  	size = ((unsigned long)pvt) + sz_pvt;
>  
>  	mci = kzalloc(size, GFP_KERNEL);
> @@ -182,11 +184,13 @@ struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
>  	 */
>  	csi = (struct csrow_info *)(((char *)mci) + ((unsigned long)csi));
>  	chi = (struct rank_info *)(((char *)mci) + ((unsigned long)chi));
> +	dimm = (struct dimm_info *)(((char *)mci) + ((unsigned long)dimm));
>  	pvt = sz_pvt ? (((char *)mci) + ((unsigned long)pvt)) : NULL;
>  
>  	/* setup index and various internal pointers */
>  	mci->mc_idx = edac_index;
>  	mci->csrows = csi;
> +	mci->dimms  = dimm;
>  	mci->pvt_info = pvt;
>  	mci->nr_csrows = nr_csrows;
>  
> @@ -205,6 +209,21 @@ struct mem_ctl_info *edac_mc_alloc(unsigned sz_pvt, unsigned nr_csrows,
>  		}
>  	}
>  
> +	/*
> +	 * By default, assumes that a per-csrow arrangement will be used,
> +	 * as most drivers are based on such assumption.
> +	 */
> +	dimm = mci->dimms;
> +	for (row = 0; row < mci->nr_csrows; row++) {
> +		for (chn = 0; chn < mci->csrows[row].nr_channels; chn++) {
> +			mci->csrows[row].channels[chn].dimm = dimm;
> +			dimm->csrow = row;
> +			dimm->csrow_channel = chn;
> +			dimm++;
> +			mci->nr_dimms++;
> +		}
> +	}

There's a double loop above this one which iterates over the same
things: rows and then channels in each row. So merge that loop with the
one above instead of repeating it here.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
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