Re: [PATCH v3 6/7] firmware: coreboot: Only populate devices in coreboot_table_init()

[Julius Werner <jwerner@chromium.org>]

On Thu, Aug 9, 2018 at 10:17 AM Stephen Boyd <swboyd@chromium.org> wrote:
>
> This function checks the header for sanity, registers a bus, and
> populates devices for each coreboot table entry. Let's just populate
> devices here and pull the other bits up into the caller so that this
> function can be repurposed for pure device creation and registration. We
> can devm()ify the memory mapping at the same time to keep error paths
> simpler.
>
> Cc: Wei-Ning Huang <wnhuang@chromium.org>
> Cc: Julius Werner <jwerner@chromium.org>
> Cc: Brian Norris <briannorris@chromium.org>
> Cc: Samuel Holland <samuel@sholland.org>
> Suggested-by: Julius Werner <jwerner@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
>  drivers/firmware/google/coreboot_table.c | 66 +++++++++++-------------
>  1 file changed, 29 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/firmware/google/coreboot_table.c b/drivers/firmware/google/coreboot_table.c
> index f343dbe86448..814913606d22 100644
> --- a/drivers/firmware/google/coreboot_table.c
> +++ b/drivers/firmware/google/coreboot_table.c
> @@ -32,8 +32,6 @@
>  #define CB_DEV(d) container_of(d, struct coreboot_device, dev)
>  #define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
>
> -static struct coreboot_table_header *ptr_header;
> -
>  static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
>  {
>         struct coreboot_device *device = CB_DEV(dev);
> @@ -94,35 +92,21 @@ void coreboot_driver_unregister(struct coreboot_driver *driver)
>  }
>  EXPORT_SYMBOL(coreboot_driver_unregister);
>
> -static int coreboot_table_init(struct device *dev, void *ptr)
> +static int coreboot_table_populate(struct device *dev, void *ptr)
>  {
>         int i, ret;
>         void *ptr_entry;
>         struct coreboot_device *device;
>         struct coreboot_table_entry *entry;
> -       struct coreboot_table_header *header;
> -
> -       ptr_header = ptr;
> -       header = ptr;
> -
> -       if (strncmp(header->signature, "LBIO", sizeof(header->signature))) {
> -               pr_warn("coreboot_table: coreboot table missing or corrupt!\n");
> -               return -ENODEV;
> -       }
> -
> -       ret = bus_register(&coreboot_bus_type);
> -       if (ret)
> -               return ret;
> +       struct coreboot_table_header *header = ptr;
>
> -       ptr_entry = ptr_header + header->header_bytes;
> +       ptr_entry = ptr + header->header_bytes;
>         for (i = 0; i < header->table_entries; i++) {
>                 entry = ptr_entry;
>
>                 device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
> -               if (!device) {
> -                       ret = -ENOMEM;
> -                       break;
> -               }
> +               if (!device)
> +                       return -ENOMEM;
>
>                 dev_set_name(&device->dev, "coreboot%d", i);
>                 device->dev.parent = dev;
> @@ -133,18 +117,13 @@ static int coreboot_table_init(struct device *dev, void *ptr)
>                 ret = device_register(&device->dev);
>                 if (ret) {
>                         put_device(&device->dev);
> -                       break;
> +                       return ret;
>                 }
>
>                 ptr_entry += entry->size;
>         }
>
> -       if (ret) {
> -               bus_unregister(&coreboot_bus_type);
> -               memunmap(ptr);
> -       }
> -
> -       return ret;
> +       return 0;
>  }
>
>  static int coreboot_table_probe(struct platform_device *pdev)
> @@ -152,7 +131,9 @@ static int coreboot_table_probe(struct platform_device *pdev)
>         resource_size_t len;
>         struct coreboot_table_header *header;
>         struct resource *res;
> +       struct device *dev = &pdev->dev;
>         void *ptr;
> +       int ret;
>
>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         if (!res)
> @@ -162,26 +143,37 @@ static int coreboot_table_probe(struct platform_device *pdev)
>         if (!res->start || !len)
>                 return -EINVAL;
>
> +       /* Map and check just the header first to make sure things are sane */
>         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
> -       if (header == NULL)
> +       if (!header)
>                 return -ENOMEM;
>
> -       ptr = memremap(res->start, header->header_bytes + header->table_bytes,
> -                      MEMREMAP_WB);
> +       if (strncmp(header->signature, "LBIO", sizeof(header->signature))) {
> +               dev_warn(dev, "coreboot table missing or corrupt!\n");
> +               return -ENODEV;

Leaking the mapping here.

> +       }
> +
> +       ptr = devm_memremap(dev, res->start,
> +                           header->header_bytes + header->table_bytes,
> +                           MEMREMAP_WB);
>         memunmap(header);
>         if (!ptr)
>                 return -ENOMEM;
>
> -       return coreboot_table_init(&pdev->dev, ptr);
> +       ret = bus_register(&coreboot_bus_type);
> +       if (ret)
> +               return ret;
> +
> +       ret = coreboot_table_populate(dev, ptr);
> +       if (ret)
> +               bus_unregister(&coreboot_bus_type);
> +
> +       return ret;
>  }
>
>  static int coreboot_table_remove(struct platform_device *pdev)
>  {
> -       if (ptr_header) {
> -               bus_unregister(&coreboot_bus_type);
> -               memunmap(ptr_header);
> -               ptr_header = NULL;
> -       }
> +       bus_unregister(&coreboot_bus_type);
>
>         return 0;
>  }
> --
> Sent by a computer through tubes
>