Re: [PATCH v4 1/3] fpga: mgr: Use standard dev_release for class driver

[Russ Weight <russell.h.weight@intel.com>]

On 6/7/21 6:40 PM, Xu Yilun wrote:
> On Mon, Jun 07, 2021 at 04:50:58PM -0700, Russ Weight wrote:
>>
>> On 6/5/21 8:42 AM, Xu Yilun wrote:
>>> On Thu, Jun 03, 2021 at 03:45:17PM -0700, Russ Weight wrote:
>>>> On 6/1/21 5:38 PM, Russ Weight wrote:
>>>>> On 6/1/21 4:24 PM, Tom Rix wrote:
>>>>>> On 5/28/21 2:57 PM, Russ Weight wrote:
>>>>>>> The FPGA manager class driver data structure is being treated as a
>>>>>>> managed resource instead of using standard dev_release call-back
>>>>>>> to release the class data structure. This change removes the
>>>>>>> managed resource code for the freeing of the class data structure
>>>>>>> and combines the create() and register() functions into a single
>>>>>>> register() function.
>>>>>>>
>>>>>>> The devm_fpga_mgr_register() function is retained.
>>>>>>>
>>>>>>> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
>>>>>>> ---
>>>>>>> v4:
>>>>>>>    - Added the compat_id parameter to fpga_mgr_register() and
>>>>>> On a refactor, it is best to do the refactoring as mechanically as possible.
>>>>>>
>>>>>> While compat_id may be useful, it should be done in a separate patch.
>>>>> These would have to be included with the changes merge the create and register
>>>>> functions into a single function.
>>>>>
>>>>>> Unless it is really needed for your next security update patch consider resubmitting later
>>>>>>
>>>>>>>      devm_fpga_mgr_register() to ensure that the compat_id is set before
>>>>>>>      the device_register() call.
>>>>>>> v3:
>>>>>>>    - Cleaned up comment header for fpga_mgr_register()
>>>>>>>    - Fix error return on ida_simple_get() failure
>>>>>>> v2:
>>>>>>>    - Restored devm_fpga_mgr_register() functionality, adapted for the combined
>>>>>>>      create/register functionality.
>>>>>>>    - All previous callers of devm_fpga_mgr_register() will continue to call
>>>>>>>      devm_fpga_mgr_register().
>>>>>>>    - replaced unnecessary ternary operators in return statements with standard
>>>>>>>      if conditions.
>>>>>>> ---
>>>>>>>   drivers/fpga/altera-cvp.c        |  12 +--
>>>>>>>   drivers/fpga/altera-pr-ip-core.c |   9 +-
>>>>>>>   drivers/fpga/altera-ps-spi.c     |  10 +-
>>>>>>>   drivers/fpga/dfl-fme-mgr.c       |  12 +--
>>>>>>>   drivers/fpga/fpga-mgr.c          | 168 +++++++++----------------------
>>>>>>>   drivers/fpga/ice40-spi.c         |  10 +-
>>>>>>>   drivers/fpga/machxo2-spi.c       |  10 +-
>>>>>>>   drivers/fpga/socfpga-a10.c       |  16 ++-
>>>>>>>   drivers/fpga/socfpga.c           |  10 +-
>>>>>>>   drivers/fpga/stratix10-soc.c     |  15 +--
>>>>>>>   drivers/fpga/ts73xx-fpga.c       |  10 +-
>>>>>>>   drivers/fpga/xilinx-spi.c        |  12 +--
>>>>>>>   drivers/fpga/zynq-fpga.c         |  16 ++-
>>>>>>>   drivers/fpga/zynqmp-fpga.c       |  10 +-
>>>>>>>   include/linux/fpga/fpga-mgr.h    |  19 ++--
>>>>>>>   15 files changed, 120 insertions(+), 219 deletions(-)
>>>>>> ./Documentation/driver-api/fpga/fpga-mgr.rst
>>>>>>
>>>>>> still refers to fpga_mgr_create.
>>>>> Thanks for catching that.
>>>>>
>>>>>>> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
>>>>>>> index 4e0edb60bfba..25eaa97ae7aa 100644
>>>>>>> --- a/drivers/fpga/altera-cvp.c
>>>>>>> +++ b/drivers/fpga/altera-cvp.c
>>>>>>> @@ -652,19 +652,15 @@ static int altera_cvp_probe(struct pci_dev *pdev,
>>>>>>>       snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s @%s",
>>>>>>>            ALTERA_CVP_MGR_NAME, pci_name(pdev));
>>>>>>>   -    mgr = devm_fpga_mgr_create(&pdev->dev, conf->mgr_name,
>>>>>>> -                   &altera_cvp_ops, conf);
>>>>>>> -    if (!mgr) {
>>>>>>> -        ret = -ENOMEM;
>>>>>>> +    mgr = fpga_mgr_register(&pdev->dev, conf->mgr_name, NULL,
>>>>>>> +                &altera_cvp_ops, conf);
>>>>>>> +    if (IS_ERR(mgr)) {
>>>>>>> +        ret = PTR_ERR(mgr);
>>>>>>>           goto err_unmap;
>>>>>>>       }
>>>>>>>         pci_set_drvdata(pdev, mgr);
>>>>>>>   -    ret = fpga_mgr_register(mgr);
>>>>>>> -    if (ret)
>>>>>>> -        goto err_unmap;
>>>>>>> -
>>>>>>>       return 0;
>>>>>>>     err_unmap:
>>>>>>> diff --git a/drivers/fpga/altera-pr-ip-core.c b/drivers/fpga/altera-pr-ip-core.c
>>>>>>> index 5b130c4d9882..bfd4de1e7ac5 100644
>>>>>>> --- a/drivers/fpga/altera-pr-ip-core.c
>>>>>>> +++ b/drivers/fpga/altera-pr-ip-core.c
>>>>>>> @@ -191,11 +191,12 @@ int alt_pr_register(struct device *dev, void __iomem *reg_base)
>>>>>>>           (val & ALT_PR_CSR_STATUS_MSK) >> ALT_PR_CSR_STATUS_SFT,
>>>>>>>           (int)(val & ALT_PR_CSR_PR_START));
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, dev_name(dev), &alt_pr_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, dev_name(dev), NULL,
>>>>>>> +                     &alt_pr_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>   EXPORT_SYMBOL_GPL(alt_pr_register);
>>>>>>>   diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
>>>>>>> index 23bfd4d1ad0f..e6fc7208213c 100644
>>>>>>> --- a/drivers/fpga/altera-ps-spi.c
>>>>>>> +++ b/drivers/fpga/altera-ps-spi.c
>>>>>>> @@ -302,12 +302,12 @@ static int altera_ps_probe(struct spi_device *spi)
>>>>>>>       snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s %s",
>>>>>>>            dev_driver_string(&spi->dev), dev_name(&spi->dev));
>>>>>>>   -    mgr = devm_fpga_mgr_create(&spi->dev, conf->mgr_name,
>>>>>>> -                   &altera_ps_ops, conf);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(&spi->dev, conf->mgr_name, NULL,
>>>>>>> +                     &altera_ps_ops, conf);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(&spi->dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static const struct spi_device_id altera_ps_spi_ids[] = {
>>>>>>> diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
>>>>>>> index d5861d13b306..c9b98afa7d50 100644
>>>>>>> --- a/drivers/fpga/dfl-fme-mgr.c
>>>>>>> +++ b/drivers/fpga/dfl-fme-mgr.c
>>>>>>> @@ -308,14 +308,12 @@ static int fme_mgr_probe(struct platform_device *pdev)
>>>>>>>         fme_mgr_get_compat_id(priv->ioaddr, compat_id);
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
>>>>>>> -                   &fme_mgr_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> -
>>>>>>> -    mgr->compat_id = compat_id;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, "DFL FME FPGA Manager", compat_id,
>>>>>>> +                     &fme_mgr_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static struct platform_driver fme_mgr_driver = {
>>>>>>> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
>>>>>>> index b85bc47c91a9..d6d64ce34417 100644
>>>>>>> --- a/drivers/fpga/fpga-mgr.c
>>>>>>> +++ b/drivers/fpga/fpga-mgr.c
>>>>>>> @@ -550,20 +550,22 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
>>>>>>>   EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
>>>>>>>     /**
>>>>>>> - * fpga_mgr_create - create and initialize a FPGA manager struct
>>>>>>> + * fpga_mgr_register - create and register a FPGA Manager device
>>>>>>>    * @dev:    fpga manager device from pdev
>>>>>>>    * @name:    fpga manager name
>>>>>>> + * @compat_id:    FPGA manager id for compatibility check.
>>>>>> for consistency, use lowercase fpga
>>>>>>
>>>>>> similar issue below.
>>>>> OK
>>>>>
>>>>>>>    * @mops:    pointer to structure of fpga manager ops
>>>>>>>    * @priv:    fpga manager private data
>>>>>>>    *
>>>>>>> - * The caller of this function is responsible for freeing the struct with
>>>>>>> - * fpga_mgr_free().  Using devm_fpga_mgr_create() instead is recommended.
>>>>>>> + * The caller of this function is responsible for calling fpga_mgr_unregister().
>>>>>>> + * Using devm_fpga_mgr_register instead is recommended.
>>>>>>>    *
>>>>>>> - * Return: pointer to struct fpga_manager or NULL
>>>>>>> + * Return: struct fpga_manager pointer on success, ERR_PTR() on error.
>>>>>>>    */
>>>>>>> -struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>>>>> -                     const struct fpga_manager_ops *mops,
>>>>>>> -                     void *priv)
>>>>>>> +struct fpga_manager *
>>>>>>> +fpga_mgr_register(struct device *dev, const char *name,
>>>>>>> +          struct fpga_compat_id *compat_id,
>>>>>>> +          const struct fpga_manager_ops *mops, void *priv)
>>>>>>>   {
>>>>>>>       struct fpga_manager *mgr;
>>>>>>>       int id, ret;
>>>>>>> @@ -572,29 +574,31 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>>>>>           !mops->write_init || (!mops->write && !mops->write_sg) ||
>>>>>>>           (mops->write && mops->write_sg)) {
>>>>>>>           dev_err(dev, "Attempt to register without fpga_manager_ops\n");
>>>>>>> -        return NULL;
>>>>>>> +        return ERR_PTR(-EINVAL);
>>>>>>>       }
>>>>>>>         if (!name || !strlen(name)) {
>>>>>>>           dev_err(dev, "Attempt to register with no name!\n");
>>>>>>> -        return NULL;
>>>>>>> +        return ERR_PTR(-EINVAL);
>>>>>>>       }
>>>>>>>         mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
>>>>>>>       if (!mgr)
>>>>>>> -        return NULL;
>>>>>>> +        return ERR_PTR(-ENOMEM);
>>>>>>>         id = ida_simple_get(&fpga_mgr_ida, 0, 0, GFP_KERNEL);
>>>>>>> -    if (id < 0)
>>>>>>> +    if (id < 0) {
>>>>>>> +        ret = id;
>>>>>> ida_* returns a normal error, so needs a wrapping in
>>>>>>
>>>>>> ret = ERR_PTR(id)
>>>>> Thanks - I'll fix that
>>>> Actually, if you follow the "goto error_kfree", you will see that ret is
>>>> wrapped in ERR_PTR() in the return statement, so id does not need to be
>>>> wrapped here.
>>>>
>>>>>>>           goto error_kfree;
>>>>>>> +    }
>>>>>>>         mutex_init(&mgr->ref_mutex);
>>>>>>>         mgr->name = name;
>>>>>>> +    mgr->compat_id = compat_id;
>>>>>>>       mgr->mops = mops;
>>>>>>>       mgr->priv = priv;
>>>>>>>   -    device_initialize(&mgr->dev);
>>>>>>>       mgr->dev.class = fpga_mgr_class;
>>>>>>>       mgr->dev.groups = mops->groups;
>>>>>>>       mgr->dev.parent = dev;
>>>>>>> @@ -605,84 +609,6 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>>>>>       if (ret)
>>>>>>>           goto error_device;
>>>>>>>   -    return mgr;
>>>>>>> -
>>>>>>> -error_device:
>>>>>>> -    ida_simple_remove(&fpga_mgr_ida, id);
>>>>>>> -error_kfree:
>>>>>>> -    kfree(mgr);
>>>>>>> -
>>>>>>> -    return NULL;
>>>>>>> -}
>>>>>>> -EXPORT_SYMBOL_GPL(fpga_mgr_create);
>>>>>>> -
>>>>>>> -/**
>>>>>>> - * fpga_mgr_free - free a FPGA manager created with fpga_mgr_create()
>>>>>>> - * @mgr:    fpga manager struct
>>>>>>> - */
>>>>>>> -void fpga_mgr_free(struct fpga_manager *mgr)
>>>>>>> -{
>>>>>>> -    ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
>>>>>>> -    kfree(mgr);
>>>>>>> -}
>>>>>>> -EXPORT_SYMBOL_GPL(fpga_mgr_free);
>>>>>>> -
>>>>>>> -static void devm_fpga_mgr_release(struct device *dev, void *res)
>>>>>>> -{
>>>>>>> -    struct fpga_mgr_devres *dr = res;
>>>>>>> -
>>>>>>> -    fpga_mgr_free(dr->mgr);
>>>>>>> -}
>>>>>>> -
>>>>>>> -/**
>>>>>>> - * devm_fpga_mgr_create - create and initialize a managed FPGA manager struct
>>>>>>> - * @dev:    fpga manager device from pdev
>>>>>>> - * @name:    fpga manager name
>>>>>>> - * @mops:    pointer to structure of fpga manager ops
>>>>>>> - * @priv:    fpga manager private data
>>>>>>> - *
>>>>>>> - * This function is intended for use in a FPGA manager driver's probe function.
>>>>>>> - * After the manager driver creates the manager struct with
>>>>>>> - * devm_fpga_mgr_create(), it should register it with fpga_mgr_register().  The
>>>>>>> - * manager driver's remove function should call fpga_mgr_unregister().  The
>>>>>>> - * manager 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_mgr_register(), the struct will still get cleaned up.
>>>>>>> - *
>>>>>>> - * Return: pointer to struct fpga_manager or NULL
>>>>>>> - */
>>>>>>> -struct fpga_manager *devm_fpga_mgr_create(struct device *dev, const char *name,
>>>>>>> -                      const struct fpga_manager_ops *mops,
>>>>>>> -                      void *priv)
>>>>>>> -{
>>>>>>> -    struct fpga_mgr_devres *dr;
>>>>>>> -
>>>>>>> -    dr = devres_alloc(devm_fpga_mgr_release, sizeof(*dr), GFP_KERNEL);
>>>>>>> -    if (!dr)
>>>>>>> -        return NULL;
>>>>>>> -
>>>>>>> -    dr->mgr = fpga_mgr_create(dev, name, mops, priv);
>>>>>>> -    if (!dr->mgr) {
>>>>>>> -        devres_free(dr);
>>>>>>> -        return NULL;
>>>>>>> -    }
>>>>>>> -
>>>>>>> -    devres_add(dev, dr);
>>>>>>> -
>>>>>>> -    return dr->mgr;
>>>>>>> -}
>>>>>>> -EXPORT_SYMBOL_GPL(devm_fpga_mgr_create);
>>>>>>> -
>>>>>>> -/**
>>>>>>> - * fpga_mgr_register - register a FPGA manager
>>>>>>> - * @mgr: fpga manager struct
>>>>>>> - *
>>>>>>> - * Return: 0 on success, negative error code otherwise.
>>>>>>> - */
>>>>>>> -int fpga_mgr_register(struct fpga_manager *mgr)
>>>>>>> -{
>>>>>>> -    int ret;
>>>>>>> -
>>>>>>>       /*
>>>>>>>        * Initialize framework state by requesting low level driver read state
>>>>>>>        * from device.  FPGA may be in reset mode or may have been programmed
>>>>>>> @@ -690,18 +616,20 @@ int fpga_mgr_register(struct fpga_manager *mgr)
>>>>>>>        */
>>>>>>>       mgr->state = mgr->mops->state(mgr);
>>>>>>>   -    ret = device_add(&mgr->dev);
>>>>>>> -    if (ret)
>>>>>>> -        goto error_device;
>>>>>>> -
>>>>>>> -    dev_info(&mgr->dev, "%s registered\n", mgr->name);
>>>>>> can we keep this dev_info() line and move it below device_register() ?
>>>>> In Greg's response to my driver, he said he said that a well-behaved driver does
>>>>> not need dev_info() calls...
>>>>>>> +    ret = device_register(&mgr->dev);
>>>>>>> +    if (ret) {
>>>>>>> +        put_device(&mgr->dev);
>>>>>> pr_err() here ?
>>>>> OK - I can add a message
>>>>>
>>>>>>> +        return ERR_PTR(ret);
>>>>>>> +    }
>>>>>>>   -    return 0;
>>>>>>> +    return mgr;
>>>>>>>     error_device:
>>>>>>> -    ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
>>>>>>> +    ida_simple_remove(&fpga_mgr_ida, id);
>>>>>>> +error_kfree:
>>>>>>> +    kfree(mgr);
>>>>>>>   -    return ret;
>>>>>>> +    return ERR_PTR(ret);
>>>>>>>   }
>>>>>>>   EXPORT_SYMBOL_GPL(fpga_mgr_register);
>>>>>>>   @@ -726,14 +654,6 @@ void fpga_mgr_unregister(struct fpga_manager *mgr)
>>>>>>>   }
>>>>>>>   EXPORT_SYMBOL_GPL(fpga_mgr_unregister);
>>>>>>>   -static int fpga_mgr_devres_match(struct device *dev, void *res,
>>>>>>> -                 void *match_data)
>>>>>>> -{
>>>>>>> -    struct fpga_mgr_devres *dr = res;
>>>>>>> -
>>>>>>> -    return match_data == dr->mgr;
>>>>>>> -}
>>>>>>> -
>>>>>>>   static void devm_fpga_mgr_unregister(struct device *dev, void *res)
>>>>>>>   {
>>>>>>>       struct fpga_mgr_devres *dr = res;
>>>>>>> @@ -743,44 +663,46 @@ static void devm_fpga_mgr_unregister(struct device *dev, void *res)
>>>>>>>     /**
>>>>>>>    * devm_fpga_mgr_register - resource managed variant of fpga_mgr_register()
>>>>>>> - * @dev: managing device for this FPGA manager
>>>>>>> - * @mgr: fpga manager struct
>>>>>>> + * @dev:    fpga manager device from pdev
>>>>>>> + * @name:    fpga manager name
>>>>>>> + * @compat_id:    FPGA manager id for compatibility check.
>>>>>>> + * @mops:    pointer to structure of fpga manager ops
>>>>>>> + * @priv:    fpga manager private data
>>>>>>>    *
>>>>>>>    * This is the devres variant of fpga_mgr_register() for which the unregister
>>>>>>>    * function will be called automatically when the managing device is detached.
>>>>>>>    */
>>>>>>> -int devm_fpga_mgr_register(struct device *dev, struct fpga_manager *mgr)
>>>>>>> +struct fpga_manager *
>>>>>>> +devm_fpga_mgr_register(struct device *dev, const char *name,
>>>>>>> +               struct fpga_compat_id *compat_id,
>>>>>>> +               const struct fpga_manager_ops *mops, void *priv)
>>>>>>>   {
>>>>>>>       struct fpga_mgr_devres *dr;
>>>>>>> -    int ret;
>>>>>>> -
>>>>>>> -    /*
>>>>>>> -     * Make sure that the struct fpga_manager * that is passed in is
>>>>>>> -     * managed itself.
>>>>>>> -     */
>>>>>>> -    if (WARN_ON(!devres_find(dev, devm_fpga_mgr_release,
>>>>>>> -                 fpga_mgr_devres_match, mgr)))
>>>>>>> -        return -EINVAL;
>>>>>>> +    struct fpga_manager *mgr;
>>>>>>>         dr = devres_alloc(devm_fpga_mgr_unregister, sizeof(*dr), GFP_KERNEL);
>>>>>>>       if (!dr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +        return ERR_PTR(-ENOMEM);
>>>>>>>   -    ret = fpga_mgr_register(mgr);
>>>>>>> -    if (ret) {
>>>>>>> +    mgr = fpga_mgr_register(dev, name, compat_id, mops, priv);
>>>>>>> +    if (IS_ERR(mgr)) {
>>>>>>>           devres_free(dr);
>>>>>>> -        return ret;
>>>>>>> +        return mgr;
>>>>>>>       }
>>>>>>>         dr->mgr = mgr;
>>>>>>>       devres_add(dev, dr);
>>>>>>>   -    return 0;
>>>>>>> +    return mgr;
>>>>>>>   }
>>>>>>>   EXPORT_SYMBOL_GPL(devm_fpga_mgr_register);
>>>>>>>     static void fpga_mgr_dev_release(struct device *dev)
>>>>>>>   {
>>>>>>> +    struct fpga_manager *mgr = to_fpga_manager(dev);
>>>>>>> +
>>>>>>> +    ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
>>>>>>> +    kfree(mgr);
>>>>>>>   }
>>>>>>>     static int __init fpga_mgr_class_init(void)
>>>>>>> diff --git a/drivers/fpga/ice40-spi.c b/drivers/fpga/ice40-spi.c
>>>>>>> index 69dec5af23c3..b1c7c0713e11 100644
>>>>>>> --- a/drivers/fpga/ice40-spi.c
>>>>>>> +++ b/drivers/fpga/ice40-spi.c
>>>>>>> @@ -178,12 +178,12 @@ static int ice40_fpga_probe(struct spi_device *spi)
>>>>>>>           return ret;
>>>>>>>       }
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "Lattice iCE40 FPGA Manager",
>>>>>>> -                   &ice40_fpga_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, "Lattice iCE40 FPGA Manager",
>>>>>>> +                     NULL, &ice40_fpga_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static const struct of_device_id ice40_fpga_of_match[] = {
>>>>>>> diff --git a/drivers/fpga/machxo2-spi.c b/drivers/fpga/machxo2-spi.c
>>>>>>> index 114a64d2b7a4..75cc6efaa1b6 100644
>>>>>>> --- a/drivers/fpga/machxo2-spi.c
>>>>>>> +++ b/drivers/fpga/machxo2-spi.c
>>>>>>> @@ -366,12 +366,12 @@ static int machxo2_spi_probe(struct spi_device *spi)
>>>>>>>           return -EINVAL;
>>>>>>>       }
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "Lattice MachXO2 SPI FPGA Manager",
>>>>>>> -                   &machxo2_ops, spi);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, "Lattice MachXO2 SPI FPGA Manager",
>>>>>>> +                     NULL, &machxo2_ops, spi);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static const struct of_device_id of_match[] = {
>>>>>>> diff --git a/drivers/fpga/socfpga-a10.c b/drivers/fpga/socfpga-a10.c
>>>>>>> index 573d88bdf730..80b8891fb302 100644
>>>>>>> --- a/drivers/fpga/socfpga-a10.c
>>>>>>> +++ b/drivers/fpga/socfpga-a10.c
>>>>>>> @@ -508,19 +508,15 @@ static int socfpga_a10_fpga_probe(struct platform_device *pdev)
>>>>>>>           return -EBUSY;
>>>>>>>       }
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "SoCFPGA Arria10 FPGA Manager",
>>>>>>> -                   &socfpga_a10_fpga_mgr_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> -
>>>>>>> -    platform_set_drvdata(pdev, mgr);
>>>>>>> -
>>>>>>> -    ret = fpga_mgr_register(mgr);
>>>>>>> -    if (ret) {
>>>>>>> +    mgr = fpga_mgr_register(dev, "SoCFPGA Arria10 FPGA Manager",
>>>>>>> +                NULL, &socfpga_a10_fpga_mgr_ops, priv);
>>>>>>> +    if (IS_ERR(mgr)) {
>>>>>>>           clk_disable_unprepare(priv->clk);
>>>>>>> -        return ret;
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>       }
>>>>>>>   +    platform_set_drvdata(pdev, mgr);
>>>>>>> +
>>>>>>>       return 0;
>>>>>>>   }
>>>>>>>   diff --git a/drivers/fpga/socfpga.c b/drivers/fpga/socfpga.c
>>>>>>> index 1f467173fc1f..06edfab8a496 100644
>>>>>>> --- a/drivers/fpga/socfpga.c
>>>>>>> +++ b/drivers/fpga/socfpga.c
>>>>>>> @@ -571,12 +571,12 @@ static int socfpga_fpga_probe(struct platform_device *pdev)
>>>>>>>       if (ret)
>>>>>>>           return ret;
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
>>>>>>> -                   &socfpga_fpga_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
>>>>>>> +                     NULL, &socfpga_fpga_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     #ifdef CONFIG_OF
>>>>>>> diff --git a/drivers/fpga/stratix10-soc.c b/drivers/fpga/stratix10-soc.c
>>>>>>> index 657a70c5fc99..434094c3ac69 100644
>>>>>>> --- a/drivers/fpga/stratix10-soc.c
>>>>>>> +++ b/drivers/fpga/stratix10-soc.c
>>>>>>> @@ -425,18 +425,11 @@ static int s10_probe(struct platform_device *pdev)
>>>>>>>         init_completion(&priv->status_return_completion);
>>>>>>>   -    mgr = fpga_mgr_create(dev, "Stratix10 SOC FPGA Manager",
>>>>>>> -                  &s10_ops, priv);
>>>>>>> -    if (!mgr) {
>>>>>>> -        dev_err(dev, "unable to create FPGA manager\n");
>>>>>>> -        ret = -ENOMEM;
>>>>>>> -        goto probe_err;
>>>>>>> -    }
>>>>>>> -
>>>>>>> -    ret = fpga_mgr_register(mgr);
>>>>>>> -    if (ret) {
>>>>>>> +    mgr = fpga_mgr_register(dev, "Stratix10 SOC FPGA Manager",
>>>>>>> +                NULL, &s10_ops, priv);
>>>>>>> +    if (IS_ERR(mgr)) {
>>>>>>>           dev_err(dev, "unable to register FPGA manager\n");
>>>>>>> -        fpga_mgr_free(mgr);
>>>>>>> +        ret = PTR_ERR(mgr);
>>>>>>>           goto probe_err;
>>>>>>>       }
>>>>>>>   diff --git a/drivers/fpga/ts73xx-fpga.c b/drivers/fpga/ts73xx-fpga.c
>>>>>>> index 101f016c6ed8..5efbec2b9f9f 100644
>>>>>>> --- a/drivers/fpga/ts73xx-fpga.c
>>>>>>> +++ b/drivers/fpga/ts73xx-fpga.c
>>>>>>> @@ -122,12 +122,12 @@ static int ts73xx_fpga_probe(struct platform_device *pdev)
>>>>>>>       if (IS_ERR(priv->io_base))
>>>>>>>           return PTR_ERR(priv->io_base);
>>>>>>>   -    mgr = devm_fpga_mgr_create(kdev, "TS-73xx FPGA Manager",
>>>>>>> -                   &ts73xx_fpga_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(kdev, "TS-73xx FPGA Manager",
>>>>>> This is missing compat_id param.
>>>>> Thanks - I thought I'll do another pass and make sure I catch them all.
>>>>>
>>>>>> Similar for others.
>>>>>>
>>>>>>> +                     &ts73xx_fpga_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(kdev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static struct platform_driver ts73xx_fpga_driver = {
>>>>>>> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
>>>>>>> index fee4d0abf6bf..6f1894929687 100644
>>>>>>> --- a/drivers/fpga/xilinx-spi.c
>>>>>>> +++ b/drivers/fpga/xilinx-spi.c
>>>>>>> @@ -247,13 +247,13 @@ static int xilinx_spi_probe(struct spi_device *spi)
>>>>>>>           return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
>>>>>>>                        "Failed to get DONE gpio\n");
>>>>>>>   -    mgr = devm_fpga_mgr_create(&spi->dev,
>>>>>>> -                   "Xilinx Slave Serial FPGA Manager",
>>>>>>> -                   &xilinx_spi_ops, conf);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(&spi->dev,
>>>>>>> +                     "Xilinx Slave Serial FPGA Manager",
>>>>>>> +                     NULL, &xilinx_spi_ops, conf);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(&spi->dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static const struct of_device_id xlnx_spi_of_match[] = {
>>>>>>> diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
>>>>>>> index 07fa8d9ec675..74bbb9710f4e 100644
>>>>>>> --- a/drivers/fpga/zynq-fpga.c
>>>>>>> +++ b/drivers/fpga/zynq-fpga.c
>>>>>>> @@ -609,20 +609,16 @@ static int zynq_fpga_probe(struct platform_device *pdev)
>>>>>>>         clk_disable(priv->clk);
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "Xilinx Zynq FPGA Manager",
>>>>>>> -                   &zynq_fpga_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> -
>>>>>>> -    platform_set_drvdata(pdev, mgr);
>>>>>>> -
>>>>>>> -    err = fpga_mgr_register(mgr);
>>>>>>> -    if (err) {
>>>>>>> +    mgr = fpga_mgr_register(dev, "Xilinx Zynq FPGA Manager",
>>>>>> This is missing compat_id param as well.
>>>>>>> +                &zynq_fpga_ops, priv);
>>>>>>> +    if (IS_ERR(mgr)) {
>>>>>>>           dev_err(dev, "unable to register FPGA manager\n");
>>>>>>>           clk_unprepare(priv->clk);
>>>>>>> -        return err;
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>       }
>>>>>>>   +    platform_set_drvdata(pdev, mgr);
>>>>>>> +
>>>>>>>       return 0;
>>>>>>>   }
>>>>>>>   diff --git a/drivers/fpga/zynqmp-fpga.c b/drivers/fpga/zynqmp-fpga.c
>>>>>>> index 125743c9797f..1a6d520985be 100644
>>>>>>> --- a/drivers/fpga/zynqmp-fpga.c
>>>>>>> +++ b/drivers/fpga/zynqmp-fpga.c
>>>>>>> @@ -102,12 +102,12 @@ static int zynqmp_fpga_probe(struct platform_device *pdev)
>>>>>>>         priv->dev = dev;
>>>>>>>   -    mgr = devm_fpga_mgr_create(dev, "Xilinx ZynqMP FPGA Manager",
>>>>>>> -                   &zynqmp_fpga_ops, priv);
>>>>>>> -    if (!mgr)
>>>>>>> -        return -ENOMEM;
>>>>>>> +    mgr = devm_fpga_mgr_register(dev, "Xilinx ZynqMP FPGA Manager",
>>>>>>> +                     &zynqmp_fpga_ops, priv);
>>>>>>> +    if (IS_ERR(mgr))
>>>>>>> +        return PTR_ERR(mgr);
>>>>>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>>>>>> +    return 0;
>>>>>>>   }
>>>>>>>     static const struct of_device_id zynqmp_fpga_of_match[] = {
>>>>>>> diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
>>>>>>> index 2bc3030a69e5..3e1859cc0640 100644
>>>>>>> --- a/include/linux/fpga/fpga-mgr.h
>>>>>>> +++ b/include/linux/fpga/fpga-mgr.h
>>>>>>> @@ -191,17 +191,16 @@ struct fpga_manager *fpga_mgr_get(struct device *dev);
>>>>>>>     void fpga_mgr_put(struct fpga_manager *mgr);
>>>>>>>   -struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>>>>> -                     const struct fpga_manager_ops *mops,
>>>>>>> -                     void *priv);
>>>>>> My biggest concern is that removing this will break all oot fpga drivers.
>>>>>>
>>>>>> The other patches have similar api changes
>>>>>>
>>>>>> Having a stable api is very important.
>>>>> That is a good point. While Greg did call out the separation of the
>>>>> device_initialize() and device_add() calls, his biggest concern was with
>>>>> the empty dev_release() functions. Maybe it would be best to first submit
>>>>> a patch that only addresses the dev_release() functions? Maybe it would be
>>>>> OK to leave the create and register functions as separate functions in order
>>>>> to maintain a stable API...
>>>> On further investigation, I don't think we have much choice in changing
>>>> the API. We are almost coming full circle here. In 2018, there was only
>>>> an fpga_mgr_register() function. It was returning an errno value or zero.
>>>> It was also setting the drvdata of the parent driver with a pointer to
>>>> the resulting fpga_manager structure.
>>>>
>>>> It looks like the reason the interface was split into two (create and
>>>> register) was so that the fpga_manager pointer could be returned (by the
>>>> create function) without writing the drvdata of the parent driver:
>>>>
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7085e2a94f7df5f419e3cfb2fe809ce6564e9629
>>>>
>>>> When the interfaces were split, fpga_mgr_free() was also created to free
>>>> the memory if the register function was not called. The fpga_mgr_free()
>>>> function was also called by the fpga_mgr_dev_release() function. A later
>>>> patch was submitted to simplify the memory management for the class driver:
>>>>
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=084181fe8cc7472695b907f0018f4cd00934cb12
>>>>
>>>> It is this second commit that empties the fpga_mgr_dev_release() function
>>>> and instead uses devm_fpga_mgr_create() to manage the memory for the class
>>>> driver.
>>>>
>>>> The fix I am proposing essentially takes us back to the 2018 implementation,
>>>> but returns the fpga_manager pointer or ERR_PTR() instead of returning zero or
>>>> an errno.
>>>>
>>>> The definition of the API is integral to the memory management issue. I cannot
>>>> think of an acceptable solution for the upstream that doesn't involve
>>>> changing the API. It could result in some ifdef's in an out-of-tree driver,
>>>> but I don't think we can avoid it in this case.
>>> I agree the stable API is important, and I think it is still possible to fix
>>> the memory management issue while keeping the APIs.
>>>
>>> We should do the actual resource free work in class.dev_release(), and
>>> fpga_mgr_free should call put_device() to trigger it.
>>>
>>> And I see no problem with the current devm APIs.
>> Consider the case where both devm_fpga_mgr_create() and devm_fpga_mgr_register()
>> are called, and both succeed. When the driver is unloaded devm_fpga_mgr_release()
>> is called on behalf of the create and it will call put_device(). Then
>> devm_fpga_mgr_unregister() will be called on behalf of the register, and it
>> will call device_unregister(), which also calls put_device(). In this case, I
>> think there is an extra call to put_device(), right? Or is that not a problem?
> The real problem is the non-devm functions.
>
> fpga_mgr_create() calls device_initialize() so fpga_mgr_free() should call
> put_device() for deinitialization.
Yes - I understand that. The error case also needs to be fixed to call put_device()
on error.
>
> fpga_mgr_register() calls device_add(), so fpga_mgr_unregister() should
> call device_del().

OK - so your answer to my question is that fpga_mgr_unregister() should call
device_del() instead of device_unregister(). I can see how that will work.
I'll try to submit a new patchset today.

Thanks,

- Russ
>
> Thanks,
> Yilun
>
>> The only way I can think to avoid the extra put_device() call for this case
>> would be to set a flag when-and-if fpga_mgr_register() succeeds and then refuse
>> to call put_device() in devm_fpga_mgr_release() in order to avoid the duplicate
>> call to put_device(). But that feels like a hack to me.
>>
>> Am I missing something? Is there a cleaner way to make this work?
>>
>> - Russ
>>> Thanks,
>>> Yilun
>>>
>>>>> - Russ
>>>>>
>>>>>> My recommendation is to keep the public api and hide the change with an exported but not public function.
>>>>>>
>>>>>> Tom
>>>>>>
>>>>>>> -void fpga_mgr_free(struct fpga_manager *mgr);
>>>>>>> -int fpga_mgr_register(struct fpga_manager *mgr);
>>>>>>> +struct fpga_manager *fpga_mgr_register(struct device *dev, const char *name,
>>>>>>> +                       struct fpga_compat_id *compat_id,
>>>>>>> +                       const struct fpga_manager_ops *mops,
>>>>>>> +                       void *priv);
>>>>>>>   void fpga_mgr_unregister(struct fpga_manager *mgr);
>>>>>>>   -int devm_fpga_mgr_register(struct device *dev, struct fpga_manager *mgr);
>>>>>>> -
>>>>>>> -struct fpga_manager *devm_fpga_mgr_create(struct device *dev, const char *name,
>>>>>>> -                      const struct fpga_manager_ops *mops,
>>>>>>> -                      void *priv);
>>>>>>> +struct fpga_manager *
>>>>>>> +devm_fpga_mgr_register(struct device *dev, const char *name,
>>>>>>> +               struct fpga_compat_id *compat_id,
>>>>>>> +               const struct fpga_manager_ops *mops,
>>>>>>> +               void *priv);
>>>>>>>     #endif /*_LINUX_FPGA_MGR_H */