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Message-ID: <20251023154405.GRaPpNRQRyvfpZjfex@fat_crate.local>
Date: Thu, 23 Oct 2025 17:44:05 +0200
From: Borislav Petkov <bp@...en8.de>
To: Shubhrajyoti Datta <shubhrajyoti.datta@....com>
Cc: linux-edac@...r.kernel.org, git@....com, shubhrajyoti.datta@...il.com,
dan.carpenter@...aro.org, Michal Simek <michal.simek@....com>,
Tony Luck <tony.luck@...el.com>, James Morse <james.morse@....com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Robert Richter <rric@...nel.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] EDAC/versalnet: Refactor memory controller
initialization and cleanup
Thanks for doing this!
On Thu, Oct 16, 2025 at 10:58:39AM +0530, Shubhrajyoti Datta wrote:
> Simplify the initialization and cleanup flow for Versal Net DDRMC
> controllers in the EDAC driver. Key changes include:
>
> * Introduced `init_single_versalnet()` for per-controller setup and
> `init_versalnet()` for looping through NUM_CONTROLLERS.
> * Added proper rollback logic using `remove_single_versalnet()` when
> partial initialization fails.
> * Improved readability and maintainability by reducing duplicated code and
> consolidating error handling.
"Describe your changes in imperative mood, e.g. “make xyzzy do frotz” instead
of “[This patch] makes xyzzy do frotz” or “[I] changed xyzzy to do frotz”, as
if you are giving orders to the codebase to change its behaviour."
IOW:
"Introduce per-controller setup and teardown functions..."
and so on.
> Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@....com>
> ---
>
> drivers/edac/versalnet_edac.c | 158 +++++++++++++++++++---------------
> 1 file changed, 87 insertions(+), 71 deletions(-)
>
> diff --git a/drivers/edac/versalnet_edac.c b/drivers/edac/versalnet_edac.c
> index 1ded4c3f0213..fc7e4c43b387 100644
> --- a/drivers/edac/versalnet_edac.c
> +++ b/drivers/edac/versalnet_edac.c
> @@ -758,92 +758,111 @@ static void versal_edac_release(struct device *dev)
> kfree(dev);
> }
>
> -static int init_versalnet(struct mc_priv *priv, struct platform_device *pdev)
> +static void remove_single_versalnet(struct mc_priv *priv, int i)
remove_mc(). You don't need to stick "versalnet" in static function names.
> +{
> + struct mem_ctl_info *mci;
> +
> + mci = priv->mci[i];
> + device_unregister(mci->pdev);
> + edac_mc_del_mc(mci->pdev);
> + edac_mc_free(mci);
> +}
> +
> +static int init_single_versalnet(struct mc_priv *priv, struct platform_device *pdev, int i)
init_mc() is fine.
> {
> u32 num_chans, rank, dwidth, config;
> - struct edac_mc_layer layers[2];
> struct mem_ctl_info *mci;
> + struct edac_mc_layer layers[2];
> struct device *dev;
> enum dev_type dt;
> char *name;
> - int rc, i;
> + int rc;
>
> - for (i = 0; i < NUM_CONTROLLERS; i++) {
> - config = priv->adec[CONF + i * ADEC_NUM];
> - num_chans = FIELD_GET(MC5_NUM_CHANS_MASK, config);
> - rank = 1 << FIELD_GET(MC5_RANK_MASK, config);
> - dwidth = FIELD_GET(MC5_BUS_WIDTH_MASK, config);
> -
> - switch (dwidth) {
> - case XDDR5_BUS_WIDTH_16:
> - dt = DEV_X16;
> - break;
> - case XDDR5_BUS_WIDTH_32:
> - dt = DEV_X32;
> - break;
> - case XDDR5_BUS_WIDTH_64:
> - dt = DEV_X64;
> - break;
> - default:
> - dt = DEV_UNKNOWN;
> - }
> + config = priv->adec[CONF + i * ADEC_NUM];
> + num_chans = FIELD_GET(MC5_NUM_CHANS_MASK, config);
> + rank = 1 << FIELD_GET(MC5_RANK_MASK, config);
> + dwidth = FIELD_GET(MC5_BUS_WIDTH_MASK, config);
> +
> + switch (dwidth) {
> + case XDDR5_BUS_WIDTH_16:
> + dt = DEV_X16;
> + break;
> + case XDDR5_BUS_WIDTH_32:
> + dt = DEV_X32;
> + break;
> + case XDDR5_BUS_WIDTH_64:
> + dt = DEV_X64;
> + break;
> + default:
> + dt = DEV_UNKNOWN;
> + }
>
> - if (dt == DEV_UNKNOWN)
> - continue;
> + if (dt == DEV_UNKNOWN)
> + return 0;
>
> - /* Find the first enabled device and register that one. */
> - layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> - layers[0].size = rank;
> - layers[0].is_virt_csrow = true;
> - layers[1].type = EDAC_MC_LAYER_CHANNEL;
> - layers[1].size = num_chans;
> - layers[1].is_virt_csrow = false;
> + /* Find the first enabled device and register that one. */
> + layers[0].type = EDAC_MC_LAYER_CHIP_SELECT;
> + layers[0].size = rank;
> + layers[0].is_virt_csrow = true;
> + layers[1].type = EDAC_MC_LAYER_CHANNEL;
> + layers[1].size = num_chans;
> + layers[1].is_virt_csrow = false;
> +
> + rc = -ENOMEM;
> + mci = edac_mc_alloc(i, ARRAY_SIZE(layers), layers,
> + sizeof(struct mc_priv));
> + if (!mci) {
> + edac_printk(KERN_ERR, EDAC_MC, "Failed memory allocation for MC%d\n", i);
> + return rc;
> + }
> + priv->mci[i] = mci;
> + priv->dwidth = dt;
> +
> + dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> + if (!dev)
> + return rc;
No, do not return here but jump to the end of the function which unwinds
everything that's been setup so far. In this case, it should do
edac_mc_del_mc() what edac_mc_alloc() allocated.
This makes the unwinding loop easier in the remove function, see below.
> + dev->release = versal_edac_release;
> + name = kmalloc(32, GFP_KERNEL);
> + sprintf(name, "versal-net-ddrmc5-edac-%d", i);
> + dev->init_name = name;
> + rc = device_register(dev);
> + if (rc)
> + goto err_mc_free;
>
> - rc = -ENOMEM;
> - mci = edac_mc_alloc(i, ARRAY_SIZE(layers), layers,
> - sizeof(struct mc_priv));
> - if (!mci) {
> - edac_printk(KERN_ERR, EDAC_MC, "Failed memory allocation for MC%d\n", i);
> - goto err_alloc;
> - }
> + mci->pdev = dev;
>
> - priv->mci[i] = mci;
> - priv->dwidth = dt;
> + platform_set_drvdata(pdev, priv);
>
> - dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> - dev->release = versal_edac_release;
> - name = kmalloc(32, GFP_KERNEL);
> - sprintf(name, "versal-net-ddrmc5-edac-%d", i);
> - dev->init_name = name;
> - rc = device_register(dev);
> - if (rc)
> - goto err_alloc;
> + mc_init(mci, dev);
> + rc = edac_mc_add_mc(mci);
> + if (rc) {
> + edac_printk(KERN_ERR, EDAC_MC, "Failed to register MC%d with EDAC core\n", i);
> + goto err_unreg;
> + }
> + return 0;
> +err_unreg:
> + device_unregister(mci->pdev);
> +err_mc_free:
> + edac_mc_free(mci);
> + return rc;
> +}
>
> - mci->pdev = dev;
>
> - platform_set_drvdata(pdev, priv);
> +static int init_versalnet(struct mc_priv *priv, struct platform_device *pdev)
> +{
> + int rc, i;
>
> - mc_init(mci, dev);
> - rc = edac_mc_add_mc(mci);
> - if (rc) {
> - edac_printk(KERN_ERR, EDAC_MC, "Failed to register MC%d with EDAC core\n", i);
> - goto err_alloc;
> - }
> + for (i = 0; i < NUM_CONTROLLERS; i++) {
> + rc = init_single_versalnet(priv, pdev, i);
> + if (rc)
> + goto err_rm_versalnet;
No need for that - just unwind here and drop the label.
> }
> return 0;
>
> -err_alloc:
> - while (i--) {
> - mci = priv->mci[i];
> - if (!mci)
> - continue;
> -
> - if (mci->pdev) {
> - device_unregister(mci->pdev);
> - edac_mc_del_mc(mci->pdev);
> - }
> -
> - edac_mc_free(mci);
> +err_rm_versalnet:
> + while (i) {
> + i--;
That should be:
while (i--)
so that when you get to remove here, you remove only fully initialized memory
controllers.
> + remove_single_versalnet(priv, i);
> }
>
> return rc;
In any case, yes, do you see how it all becomes a lot simpler this way?
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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