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

[Xu Yilun <yilun.xu@intel.com>]

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.

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 */