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In-Reply-To: <20180904212237.3078-4-atull@kernel.org>
From:   Moritz Fischer <moritz.fischer.private@gmail.com>
Date:   Wed, 5 Sep 2018 08:22:17 -0700
Message-ID: <CAJYdmeO0RegP4q1tVow1U0=Zc42GEHMuqsHsvHvMqp89zZ6Wpw@mail.gmail.com>
Subject: Re: [PATCH v2 3/8] fpga: bridge: add devm_fpga_bridge_create
To:     Alan Tull <atull@kernel.org>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Randy Dunlap <rdunlap@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fpga@vger.kernel.org,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Alan,

looks good to me: Small nit inline. Not a showstopper.
On Tue, Sep 4, 2018 at 2:22 PM Alan Tull <atull@kernel.org> wrote:
>
> Add devm_fpga_bridge_create() which is the managed
> version of fpga_bridge_create().
>
> Change current bridge drivers to use
> devm_fpga_bridge_create().
>
> Signed-off-by: Alan Tull <atull@kernel.org>
Acked-by: Moritz Fischer <mdf@kernel.org>
> Suggested-by: Federico Vaga <federico.vaga@cern.ch>
> ---
> v2: add suggested-by
> ---
>  Documentation/driver-api/fpga/fpga-bridge.rst |  3 ++
>  drivers/fpga/altera-fpga2sdram.c              |  8 ++-
>  drivers/fpga/altera-freeze-bridge.c           | 13 ++---
>  drivers/fpga/altera-hps2fpga.c                |  7 ++-
>  drivers/fpga/dfl-fme-br.c                     | 11 ++--
>  drivers/fpga/fpga-bridge.c                    | 72 +++++++++++++++++++++++----
>  drivers/fpga/xilinx-pr-decoupler.c            |  4 +-
>  include/linux/fpga/fpga-bridge.h              |  4 ++
>  8 files changed, 84 insertions(+), 38 deletions(-)
>
> diff --git a/Documentation/driver-api/fpga/fpga-bridge.rst b/Documentation/driver-api/fpga/fpga-bridge.rst
> index 2c2aaca..ebbcbde 100644
> --- a/Documentation/driver-api/fpga/fpga-bridge.rst
> +++ b/Documentation/driver-api/fpga/fpga-bridge.rst
> @@ -11,6 +11,9 @@ API to implement a new FPGA bridge
>     :functions: fpga_bridge_ops
>
>  .. kernel-doc:: drivers/fpga/fpga-bridge.c
> +   :functions: devm_fpga_bridge_create
> +
> +.. kernel-doc:: drivers/fpga/fpga-bridge.c
>     :functions: fpga_bridge_create
>
>  .. kernel-doc:: drivers/fpga/fpga-bridge.c
> diff --git a/drivers/fpga/altera-fpga2sdram.c b/drivers/fpga/altera-fpga2sdram.c
> index 23660cc..a78e49c 100644
> --- a/drivers/fpga/altera-fpga2sdram.c
> +++ b/drivers/fpga/altera-fpga2sdram.c
> @@ -121,18 +121,16 @@ static int alt_fpga_bridge_probe(struct platform_device *pdev)
>         /* Get f2s bridge configuration saved in handoff register */
>         regmap_read(sysmgr, SYSMGR_ISWGRP_HANDOFF3, &priv->mask);
>
> -       br = fpga_bridge_create(dev, F2S_BRIDGE_NAME,
> -                               &altera_fpga2sdram_br_ops, priv);
> +       br = devm_fpga_bridge_create(dev, F2S_BRIDGE_NAME,
> +                                    &altera_fpga2sdram_br_ops, priv);
>         if (!br)
>                 return -ENOMEM;
>
>         platform_set_drvdata(pdev, br);
>
>         ret = fpga_bridge_register(br);
> -       if (ret) {
> -               fpga_bridge_free(br);
> +       if (ret)
>                 return ret;
> -       }
>
>         dev_info(dev, "driver initialized with handoff %08x\n", priv->mask);
>
> diff --git a/drivers/fpga/altera-freeze-bridge.c b/drivers/fpga/altera-freeze-bridge.c
> index ffd586c..dd58c4a 100644
> --- a/drivers/fpga/altera-freeze-bridge.c
> +++ b/drivers/fpga/altera-freeze-bridge.c
> @@ -213,7 +213,6 @@ static int altera_freeze_br_probe(struct platform_device *pdev)
>         struct fpga_bridge *br;
>         struct resource *res;
>         u32 status, revision;
> -       int ret;
>
>         if (!np)
>                 return -ENODEV;
> @@ -245,20 +244,14 @@ static int altera_freeze_br_probe(struct platform_device *pdev)
>
>         priv->base_addr = base_addr;
>
> -       br = fpga_bridge_create(dev, FREEZE_BRIDGE_NAME,
> -                               &altera_freeze_br_br_ops, priv);
> +       br = devm_fpga_bridge_create(dev, FREEZE_BRIDGE_NAME,
> +                                    &altera_freeze_br_br_ops, priv);
>         if (!br)
>                 return -ENOMEM;
>
>         platform_set_drvdata(pdev, br);
>
> -       ret = fpga_bridge_register(br);
> -       if (ret) {
> -               fpga_bridge_free(br);
> -               return ret;
> -       }
> -
> -       return 0;
> +       return fpga_bridge_register(br);
>  }
>
>  static int altera_freeze_br_remove(struct platform_device *pdev)
> diff --git a/drivers/fpga/altera-hps2fpga.c b/drivers/fpga/altera-hps2fpga.c
> index a974d3f..77b95f2 100644
> --- a/drivers/fpga/altera-hps2fpga.c
> +++ b/drivers/fpga/altera-hps2fpga.c
> @@ -180,7 +180,8 @@ static int alt_fpga_bridge_probe(struct platform_device *pdev)
>                 }
>         }
>
> -       br = fpga_bridge_create(dev, priv->name, &altera_hps2fpga_br_ops, priv);
> +       br = devm_fpga_bridge_create(dev, priv->name,
> +                                    &altera_hps2fpga_br_ops, priv);
>         if (!br) {
>                 ret = -ENOMEM;
>                 goto err;
> @@ -190,12 +191,10 @@ static int alt_fpga_bridge_probe(struct platform_device *pdev)
>
>         ret = fpga_bridge_register(br);
>         if (ret)
> -               goto err_free;
> +               goto err;
>
>         return 0;
>
> -err_free:
> -       fpga_bridge_free(br);
>  err:
>         clk_disable_unprepare(priv->clk);
>
> diff --git a/drivers/fpga/dfl-fme-br.c b/drivers/fpga/dfl-fme-br.c
> index 7cc041d..3ff9f3a 100644
> --- a/drivers/fpga/dfl-fme-br.c
> +++ b/drivers/fpga/dfl-fme-br.c
> @@ -61,7 +61,6 @@ static int fme_br_probe(struct platform_device *pdev)
>         struct device *dev = &pdev->dev;
>         struct fme_br_priv *priv;
>         struct fpga_bridge *br;
> -       int ret;
>
>         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>         if (!priv)
> @@ -69,18 +68,14 @@ static int fme_br_probe(struct platform_device *pdev)
>
>         priv->pdata = dev_get_platdata(dev);
>
> -       br = fpga_bridge_create(dev, "DFL FPGA FME Bridge",
> -                               &fme_bridge_ops, priv);
> +       br = devm_fpga_bridge_create(dev, "DFL FPGA FME Bridge",
> +                                    &fme_bridge_ops, priv);
>         if (!br)
>                 return -ENOMEM;
>
>         platform_set_drvdata(pdev, br);
>
> -       ret = fpga_bridge_register(br);
> -       if (ret)
> -               fpga_bridge_free(br);
> -
> -       return ret;
> +       return fpga_bridge_register(br);
>  }
>
>  static int fme_br_remove(struct platform_device *pdev)
> diff --git a/drivers/fpga/fpga-bridge.c b/drivers/fpga/fpga-bridge.c
> index 24b8f98..c39d35f 100644
> --- a/drivers/fpga/fpga-bridge.c
> +++ b/drivers/fpga/fpga-bridge.c
> @@ -324,6 +324,9 @@ ATTRIBUTE_GROUPS(fpga_bridge);
>   * @br_ops:    pointer to structure of fpga bridge ops
>   * @priv:      FPGA bridge private data
>   *
> + * The caller of this function is responsible for freeing the bridge with
> + * fpga_bridge_free().  Using devm_fpga_bridge_create() instead is recommended.
> + *
>   * Return: struct fpga_bridge or NULL
>   */
>  struct fpga_bridge *fpga_bridge_create(struct device *dev, const char *name,
> @@ -378,8 +381,8 @@ struct fpga_bridge *fpga_bridge_create(struct device *dev, const char *name,
>  EXPORT_SYMBOL_GPL(fpga_bridge_create);
>
>  /**
> - * fpga_bridge_free - free a fpga bridge and its id
> - * @bridge:    FPGA bridge struct created by fpga_bridge_create
> + * fpga_bridge_free - free a fpga bridge created by fpga_bridge_create()
> + * @bridge:    FPGA bridge struct
>   */
>  void fpga_bridge_free(struct fpga_bridge *bridge)
>  {
> @@ -388,9 +391,56 @@ void fpga_bridge_free(struct fpga_bridge *bridge)
>  }
>  EXPORT_SYMBOL_GPL(fpga_bridge_free);
>
> +static void devm_fpga_bridge_release(struct device *dev, void *res)
> +{
> +       struct fpga_bridge *bridge = *(struct fpga_bridge **)res;
> +
> +       fpga_bridge_free(bridge);
> +}
> +
>  /**
> - * fpga_bridge_register - register a fpga bridge
> - * @bridge:    FPGA bridge struct created by fpga_bridge_create
> + * devm_fpga_bridge_create - create and init a managed struct fpga_bridge
> + * @dev:       FPGA bridge device from pdev
> + * @name:      FPGA bridge name
> + * @br_ops:    pointer to structure of fpga bridge ops
> + * @priv:      FPGA bridge private data
> + *
> + * This function is intended for use in a FPGA bridge driver's probe function.
> + * After the bridge driver creates the struct with devm_fpga_bridge_create(), it
> + * should register the bridge with fpga_bridge_register().  The bridge driver's
> + * remove function should call fpga_bridge_unregister().  The bridge struct
> + * allocated with this function will be freed automatically on driver detach.
> + * This includes the case of a probe function returning error before calling
> + * fpga_bridge_register(), the struct will still get cleaned up.
> + *
> + *  Return: struct fpga_bridge or NULL
> + */
> +struct fpga_bridge
> +*devm_fpga_bridge_create(struct device *dev, const char *name,
> +                        const struct fpga_bridge_ops *br_ops, void *priv)
> +{
> +       struct fpga_bridge **ptr, *bridge;
> +
> +       ptr = devres_alloc(devm_fpga_bridge_release, sizeof(*ptr), GFP_KERNEL);
> +       if (!ptr)
> +               return NULL;
> +
> +       bridge = fpga_bridge_create(dev, name, br_ops, priv);
> +       if (!bridge) {
> +               devres_free(ptr);
> +       } else {
> +               *ptr = bridge;
> +               devres_add(dev, ptr);
> +       }
> +
> +       return bridge;
> +}
> +EXPORT_SYMBOL_GPL(devm_fpga_bridge_create);
> +
> +/**
> + * fpga_bridge_register - register a FPGA bridge
> + *
> + * @bridge: FPGA bridge struct
>   *
>   * Return: 0 for success, error code otherwise.
>   */
> @@ -412,8 +462,15 @@ int fpga_bridge_register(struct fpga_bridge *bridge)
>  EXPORT_SYMBOL_GPL(fpga_bridge_register);
>
>  /**
> - * fpga_bridge_unregister - unregister and free a fpga bridge
> - * @bridge:    FPGA bridge struct created by fpga_bridge_create
> + * fpga_bridge_unregister - unregister a FPGA bridge
> + *
> + * @bridge: FPGA bridge struct
> + *
> + * This function is intended for use in a FPGA bridge driver's remove function.
> + * If the bridge was created with devm_fpga_bridge_create(), the bridge struct
> + * will be automatically freed.  If the bridge was created with
> + * fpga_bridge_create(), the caller is responsible for freeing the bridge with
> + * fpga_bridge_free().

I find the formulation somewhat confusing, since it could be
interpreted as if you
used the devm_() functions you don't have to call unregister().
>   */
>  void fpga_bridge_unregister(struct fpga_bridge *bridge)
>  {
> @@ -430,9 +487,6 @@ EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
>
>  static void fpga_bridge_dev_release(struct device *dev)
>  {
> -       struct fpga_bridge *bridge = to_fpga_bridge(dev);
> -
> -       fpga_bridge_free(bridge);
>  }
>
>  static int __init fpga_bridge_dev_init(void)
> diff --git a/drivers/fpga/xilinx-pr-decoupler.c b/drivers/fpga/xilinx-pr-decoupler.c
> index 07ba153..6410361 100644
> --- a/drivers/fpga/xilinx-pr-decoupler.c
> +++ b/drivers/fpga/xilinx-pr-decoupler.c
> @@ -121,8 +121,8 @@ static int xlnx_pr_decoupler_probe(struct platform_device *pdev)
>
>         clk_disable(priv->clk);
>
> -       br = fpga_bridge_create(&pdev->dev, "Xilinx PR Decoupler",
> -                               &xlnx_pr_decoupler_br_ops, priv);
> +       br = devm_fpga_bridge_create(&pdev->dev, "Xilinx PR Decoupler",
> +                                    &xlnx_pr_decoupler_br_ops, priv);
>         if (!br) {
>                 err = -ENOMEM;
>                 goto err_clk;
> diff --git a/include/linux/fpga/fpga-bridge.h b/include/linux/fpga/fpga-bridge.h
> index ce550fc..817600a 100644
> --- a/include/linux/fpga/fpga-bridge.h
> +++ b/include/linux/fpga/fpga-bridge.h
> @@ -69,4 +69,8 @@ void fpga_bridge_free(struct fpga_bridge *br);
>  int fpga_bridge_register(struct fpga_bridge *br);
>  void fpga_bridge_unregister(struct fpga_bridge *br);
>
> +struct fpga_bridge
> +*devm_fpga_bridge_create(struct device *dev, const char *name,
> +                        const struct fpga_bridge_ops *br_ops, void *priv);
> +
>  #endif /* _LINUX_FPGA_BRIDGE_H */
> --
> 2.7.4
>

Thanks,

Moritz