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Message-ID: <1aa50550adfb3917e94dd4f553ee88005133cd15.camel@intel.com>
Date: Tue, 9 Apr 2024 23:56:19 +0000
From: "Colberg, Peter" <peter.colberg@...el.com>
To: "Wu, Hao" <hao.wu@...el.com>, "mdf@...nel.org" <mdf@...nel.org>,
"linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>, "Xu, Yilun"
<yilun.xu@...el.com>, "Rix, Tom" <trix@...hat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "russ.weight@...ux.dev" <russ.weight@...ux.dev>, "Pagani, Marco"
<marpagan@...hat.com>, "matthew.gerlach@...ux.intel.com"
<matthew.gerlach@...ux.intel.com>
Subject: Re: [RFC PATCH v2 3/9] fpga: dfl: migrate AFU MMIO region management
driver to dfl_feature_dev_data
On Tue, 2024-04-09 at 19:39 -0400, Peter Colberg wrote:
> This change separates out most of the symbol name changes required by this
> patch series for the file: drivers/fpga/dfl-afu-region.c. This is done to
> split a single monolithic change into multiple, smaller patches at the
> request of the maintainer.
>
> Signed-off-by: Peter Colberg <peter.colberg@...el.com>
> ---
> v2:
> - Split monolithic patch into series at request of maintainer
> ---
> drivers/fpga/dfl-afu-region.c | 51 ++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/fpga/dfl-afu-region.c b/drivers/fpga/dfl-afu-region.c
> index 2e7b41629406..b11a5b21e666 100644
> --- a/drivers/fpga/dfl-afu-region.c
> +++ b/drivers/fpga/dfl-afu-region.c
> @@ -12,11 +12,11 @@
>
> /**
> * afu_mmio_region_init - init function for afu mmio region support
> - * @pdata: afu platform device's pdata.
> + * @fdata: afu feature dev data
> */
> -void afu_mmio_region_init(struct dfl_feature_platform_data *pdata)
> +void afu_mmio_region_init(struct dfl_feature_dev_data *fdata)
> {
> - struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
> + struct dfl_afu *afu = dfl_fpga_fdata_get_private(fdata);
>
> INIT_LIST_HEAD(&afu->regions);
> }
> @@ -39,7 +39,7 @@ static struct dfl_afu_mmio_region *get_region_by_index(struct dfl_afu *afu,
> /**
> * afu_mmio_region_add - add a mmio region to given feature dev.
> *
> - * @pdata: afu platform device's pdata.
> + * @fdata: afu feature dev data
> * @region_index: region index.
> * @region_size: region size.
> * @phys: region's physical address of this region.
> @@ -47,14 +47,15 @@ static struct dfl_afu_mmio_region *get_region_by_index(struct dfl_afu *afu,
> *
> * Return: 0 on success, negative error code otherwise.
> */
> -int afu_mmio_region_add(struct dfl_feature_platform_data *pdata,
> +int afu_mmio_region_add(struct dfl_feature_dev_data *fdata,
> u32 region_index, u64 region_size, u64 phys, u32 flags)
> {
> + struct device *dev = &fdata->dev->dev;
> struct dfl_afu_mmio_region *region;
> struct dfl_afu *afu;
> int ret = 0;
>
> - region = devm_kzalloc(&pdata->dev->dev, sizeof(*region), GFP_KERNEL);
> + region = devm_kzalloc(dev, sizeof(*region), GFP_KERNEL);
> if (!region)
> return -ENOMEM;
>
> @@ -63,13 +64,13 @@ int afu_mmio_region_add(struct dfl_feature_platform_data *pdata,
> region->phys = phys;
> region->flags = flags;
>
> - mutex_lock(&pdata->lock);
> + mutex_lock(&fdata->lock);
>
> - afu = dfl_fpga_pdata_get_private(pdata);
> + afu = dfl_fpga_fdata_get_private(fdata);
>
> /* check if @index already exists */
> if (get_region_by_index(afu, region_index)) {
> - mutex_unlock(&pdata->lock);
> + mutex_unlock(&fdata->lock);
> ret = -EEXIST;
> goto exit;
> }
> @@ -80,37 +81,37 @@ int afu_mmio_region_add(struct dfl_feature_platform_data *pdata,
>
> afu->region_cur_offset += region_size;
> afu->num_regions++;
> - mutex_unlock(&pdata->lock);
> + mutex_unlock(&fdata->lock);
>
> return 0;
>
> exit:
> - devm_kfree(&pdata->dev->dev, region);
> + devm_kfree(dev, region);
An internal reviewer commented that calling devm_kfree() in almost all
cases shows a misunderstanding of object lifetime and may unveil bugs.
They suggested to either drop the explicit devm_kfree(), or move from
devm_*() to plain allocation.
I could not find specific documentation on the recommended use cases
for devm_kfree() to immediately free a resource on error, but the
description of devres groups advises that explicit freeing using
devres_release_group() is usually useful in midlayer drivers where
interface functions should not have side effects [1].
Which implementation would you prefer and why? Dropping devm_kfree(),
moving to plain allocation, or leaving everything as is?
[1] https://docs.kernel.org/driver-api/driver-model/devres.html#devres-group
Thanks,
Peter
> return ret;
> }
>
> /**
> * afu_mmio_region_destroy - destroy all mmio regions under given feature dev.
> - * @pdata: afu platform device's pdata.
> + * @fdata: afu feature dev data
> */
> -void afu_mmio_region_destroy(struct dfl_feature_platform_data *pdata)
> +void afu_mmio_region_destroy(struct dfl_feature_dev_data *fdata)
> {
> - struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
> + struct dfl_afu *afu = dfl_fpga_fdata_get_private(fdata);
> struct dfl_afu_mmio_region *tmp, *region;
>
> list_for_each_entry_safe(region, tmp, &afu->regions, node)
> - devm_kfree(&pdata->dev->dev, region);
> + devm_kfree(&fdata->dev->dev, region);
> }
>
> /**
> * afu_mmio_region_get_by_index - find an afu region by index.
> - * @pdata: afu platform device's pdata.
> + * @fdata: afu feature dev data
> * @region_index: region index.
> * @pregion: ptr to region for result.
> *
> * Return: 0 on success, negative error code otherwise.
> */
> -int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
> +int afu_mmio_region_get_by_index(struct dfl_feature_dev_data *fdata,
> u32 region_index,
> struct dfl_afu_mmio_region *pregion)
> {
> @@ -118,8 +119,8 @@ int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
> struct dfl_afu *afu;
> int ret = 0;
>
> - mutex_lock(&pdata->lock);
> - afu = dfl_fpga_pdata_get_private(pdata);
> + mutex_lock(&fdata->lock);
> + afu = dfl_fpga_fdata_get_private(fdata);
> region = get_region_by_index(afu, region_index);
> if (!region) {
> ret = -EINVAL;
> @@ -127,14 +128,14 @@ int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
> }
> *pregion = *region;
> exit:
> - mutex_unlock(&pdata->lock);
> + mutex_unlock(&fdata->lock);
> return ret;
> }
>
> /**
> * afu_mmio_region_get_by_offset - find an afu mmio region by offset and size
> *
> - * @pdata: afu platform device's pdata.
> + * @fdata: afu feature dev data
> * @offset: region offset from start of the device fd.
> * @size: region size.
> * @pregion: ptr to region for result.
> @@ -144,7 +145,7 @@ int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
> *
> * Return: 0 on success, negative error code otherwise.
> */
> -int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
> +int afu_mmio_region_get_by_offset(struct dfl_feature_dev_data *fdata,
> u64 offset, u64 size,
> struct dfl_afu_mmio_region *pregion)
> {
> @@ -152,8 +153,8 @@ int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
> struct dfl_afu *afu;
> int ret = 0;
>
> - mutex_lock(&pdata->lock);
> - afu = dfl_fpga_pdata_get_private(pdata);
> + mutex_lock(&fdata->lock);
> + afu = dfl_fpga_fdata_get_private(fdata);
> for_each_region(region, afu)
> if (region->offset <= offset &&
> region->offset + region->size >= offset + size) {
> @@ -162,6 +163,6 @@ int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
> }
> ret = -EINVAL;
> exit:
> - mutex_unlock(&pdata->lock);
> + mutex_unlock(&fdata->lock);
> return ret;
> }
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