Re: [PATCH v2] fpga: altera-cvp: fix probing for multiple FPGAs on the bus

[Alan Tull <atull@kernel.org>]

On Wed, Nov 7, 2018 at 4:20 PM Anatolij Gustschin <agust@denx.de> wrote:

Hi Anatolij,

Looks good!

>
> Currently registering CvP managers works only for first probed CvP
> device, for all other devices it is refused due to duplicated chkcfg
> sysfs entry:
>
> fpga_manager fpga3: Altera CvP FPGA Manager @0000:0c:00.0 registered
> sysfs: cannot create duplicate filename '/bus/pci/drivers/altera-cvp/chkcfg'
> CPU: 0 PID: 3808 Comm: bash Tainted: G           O      4.19.0-custom+ #5
> Call Trace:
>   dump_stack+0x46/0x5b
>   sysfs_warn_dup+0x53/0x60
>   sysfs_add_file_mode_ns+0x16d/0x180
>   sysfs_create_file_ns+0x51/0x60
>   altera_cvp_probe+0x16f/0x2a0 [altera_cvp]
>   local_pci_probe+0x3f/0xa0
>   ? pci_match_device+0xb1/0xf0
>   pci_device_probe+0x116/0x170
>   really_probe+0x21b/0x2c0
>   driver_probe_device+0x4b/0xe0
>   bind_store+0xcb/0x130
>   kernfs_fop_write+0xfd/0x180
>   __vfs_write+0x21/0x150
>   ? selinux_file_permission+0xdc/0x130
>   vfs_write+0xa8/0x1a0
>   ? find_vma+0xd/0x60
>   ksys_write+0x3d/0x90
>   do_syscall_64+0x44/0xf0
>   entry_SYSCALL_64_after_hwframe+0x44/0xa9
>   ...
>  altera-cvp 0000:0c:00.0: Can't create sysfs chkcfg file
>  fpga_manager fpga3: fpga_mgr_unregister Altera CvP FPGA Manager @0000:0c:00.0
>
> Move chkcfg creation to module init as suggested by Alan.
>
> Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Alan Tull <atull@kernel.org>

> ---
> Changes in v2:
>  - don't add a counter, move sysfs entry creation to module init instead
>
>  drivers/fpga/altera-cvp.c | 34 ++++++++++++++++++++++++----------
>  1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> index 144fa2a4d4cc..74bf1e8ff616 100644
> --- a/drivers/fpga/altera-cvp.c
> +++ b/drivers/fpga/altera-cvp.c
> @@ -466,14 +466,6 @@ static int altera_cvp_probe(struct pci_dev *pdev,
>         if (ret)
>                 goto err_unmap;
>
> -       ret = driver_create_file(&altera_cvp_driver.driver,
> -                                &driver_attr_chkcfg);
> -       if (ret) {
> -               dev_err(&pdev->dev, "Can't create sysfs chkcfg file\n");
> -               fpga_mgr_unregister(mgr);
> -               goto err_unmap;
> -       }
> -
>         return 0;
>
>  err_unmap:
> @@ -492,7 +484,6 @@ static void altera_cvp_remove(struct pci_dev *pdev)
>         struct altera_cvp_conf *conf = mgr->priv;
>         u16 cmd;
>
> -       driver_remove_file(&altera_cvp_driver.driver, &driver_attr_chkcfg);
>         fpga_mgr_unregister(mgr);
>         if (conf->map)
>                 pci_iounmap(pdev, conf->map);
> @@ -502,7 +493,30 @@ static void altera_cvp_remove(struct pci_dev *pdev)
>         pci_write_config_word(pdev, PCI_COMMAND, cmd);
>  }
>
> -module_pci_driver(altera_cvp_driver);
> +static int __init altera_cvp_init(void)
> +{
> +       int ret;
> +
> +       ret = pci_register_driver(&altera_cvp_driver);
> +       if (ret)
> +               return ret;
> +
> +       ret = driver_create_file(&altera_cvp_driver.driver,
> +                                &driver_attr_chkcfg);
> +       if (ret)
> +               pr_warn("Can't create sysfs chkcfg file\n");
> +
> +       return 0;
> +}
> +
> +static void __exit altera_cvp_exit(void)
> +{
> +       driver_remove_file(&altera_cvp_driver.driver, &driver_attr_chkcfg);
> +       pci_unregister_driver(&altera_cvp_driver);
> +}
> +
> +module_init(altera_cvp_init);
> +module_exit(altera_cvp_exit);
>
>  MODULE_LICENSE("GPL v2");
>  MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
> --
> 2.17.1
>