linux-kernel - Re: [PATCH v2 08/10] EDAC/ghes: Carve out MC device handling into separate functions

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Date:   Mon, 27 Apr 2020 18:38:56 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Robert Richter <rrichter@...vell.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        James Morse <james.morse@....com>,
        Aristeu Rozanski <aris@...hat.com>,
        Matthias Brugger <mbrugger@...e.com>,
        linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 08/10] EDAC/ghes: Carve out MC device handling into
 separate functions

On Wed, Apr 22, 2020 at 01:58:12PM +0200, Robert Richter wrote:
> The functions are too long, carve out code that handles MC devices
> into the new functions ghes_mc_create(), ghes_mc_add_or_free() and
> ghes_mc_free(). Apart from better code readability the functions can
> be reused and the implementation of the error paths becomes easier.
> 
> Signed-off-by: Robert Richter <rrichter@...vell.com>
> ---
>  drivers/edac/ghes_edac.c | 141 +++++++++++++++++++++++----------------
>  1 file changed, 83 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
> index 4eadc5b344c8..af0a769071f4 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -535,16 +535,88 @@ static struct acpi_platform_list plat_list[] = {
>  	{ } /* End */
>  };
>  
> -int ghes_edac_register(struct ghes *ghes, struct device *dev)
> +static struct mem_ctl_info *ghes_mc_create(struct device *dev, int mc_idx,
> +					int num_dimm)

Align arguments on the opening brace. The other functions need that too.

>  {
> -	bool fake = false;
> -	int rc = 0, num_dimm = 0;
> +	struct edac_mc_layer layers[1];
>  	struct mem_ctl_info *mci;
>  	struct ghes_mci *pvt;
> -	struct edac_mc_layer layers[1];
> -	struct dimm_fill dimm_fill;
> +
> +	layers[0].type = EDAC_MC_LAYER_ALL_MEM;
> +	layers[0].size = num_dimm;
> +	layers[0].is_virt_csrow = true;
> +
> +	mci = edac_mc_alloc(mc_idx, ARRAY_SIZE(layers), layers, sizeof(*pvt));
> +	if (!mci)
> +		return NULL;
> +
> +	pvt		= mci->pvt_info;
> +	pvt->mci	= mci;
> +
> +	mci->pdev = dev;
> +	mci->mtype_cap = MEM_FLAG_EMPTY;
> +	mci->edac_ctl_cap = EDAC_FLAG_NONE;
> +	mci->edac_cap = EDAC_FLAG_NONE;
> +	mci->mod_name = "ghes_edac.c";
> +	mci->ctl_name = "ghes_edac";
> +	mci->dev_name = "ghes";
> +
> +	return mci;
> +}
> +
> +static int ghes_mc_add_or_free(struct mem_ctl_info *mci,
> +			struct list_head *dimm_list)

No, I think we talked about this already. This function should be
called:

	ghes_mc_add()

and should do one thing and one thing only in good old unix tradition:
add the MC.

> +{
>  	unsigned long flags;
> -	int idx = -1;
> +	int rc;
> +
> +	rc = edac_mc_add_mc(mci);
> +	if (rc < 0) {

> +		ghes_dimm_release(dimm_list);
> +		edac_mc_free(mci);
> +		return rc;

Those last three lines should be called by the *caller* of
ghes_mc_add(), when latter returns an error value.

> +	}
> +
> +	spin_lock_irqsave(&ghes_lock, flags);
> +	ghes_pvt = mci->pvt_info;
> +	list_splice_tail(dimm_list, &ghes_dimm_list);
> +	spin_unlock_irqrestore(&ghes_lock, flags);
> +
> +	return 0;
> +}
> +
> +static void ghes_mc_free(void)
> +{
> +	struct mem_ctl_info *mci;
> +	unsigned long flags;
> +	LIST_HEAD(dimm_list);
> +
> +	/*
> +	 * Wait for the irq handler being finished.
> +	 */
> +	spin_lock_irqsave(&ghes_lock, flags);
> +	mci = ghes_pvt ? ghes_pvt->mci : NULL;
> +	ghes_pvt = NULL;
> +	list_splice_init(&ghes_dimm_list, &dimm_list);
> +	spin_unlock_irqrestore(&ghes_lock, flags);
> +
> +	ghes_dimm_release(&dimm_list);
> +
> +	if (!mci)
> +		return;
> +
> +	mci = edac_mc_del_mc(mci->pdev);
> +	if (mci)
> +		edac_mc_free(mci);
> +}

This function needs to do only freeing of the mc. The list splicing and
dimm releasing needs to be done by its caller, before calling it.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette