Re: [PATCH v2 05/11] firmware: use helpers for setting up a temporary cache timeout

[Kees Cook]

On Fri, Feb 23, 2018 at 6:46 PM, Luis R. Rodriguez <mcgrof@xxxxxxxxxx> wrote:
> We only use the timeout for the firmware fallback mechanism
> except for trying to set the timeout during the cache setup
> for resume/suspend. For those cases, setting the timeout should
> be a no-op, so just reflect this in code by adding helpers for it.
>
> This change introduces no functional changes.
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>

Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

> ---
>  drivers/base/firmware_loader.c | 49 ++++++++++++++++++++++++++----------------
>  1 file changed, 30 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/base/firmware_loader.c b/drivers/base/firmware_loader.c
> index 59dba794ce1a..2d819875348d 100644
> --- a/drivers/base/firmware_loader.c
> +++ b/drivers/base/firmware_loader.c
> @@ -191,13 +191,6 @@ static inline bool fw_is_builtin_firmware(const struct firmware *fw)
>  }
>  #endif
>
> -static int loading_timeout = 60;       /* In seconds */
> -
> -static inline long firmware_loading_timeout(void)
> -{
> -       return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
> -}
> -
>  static void fw_state_init(struct fw_priv *fw_priv)
>  {
>         struct fw_state *fw_st = &fw_priv->fw_st;
> @@ -282,6 +275,32 @@ static const struct firmware_fallback_config fw_fallback_config = {
>         .force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
>  };
>
> +static int old_timeout;
> +static int loading_timeout = 60;       /* In seconds */
> +
> +static inline long firmware_loading_timeout(void)
> +{
> +       return loading_timeout > 0 ? loading_timeout * HZ : MAX_JIFFY_OFFSET;
> +}
> +
> +/*
> + * use small loading timeout for caching devices' firmware because all these
> + * firmware images have been loaded successfully at lease once, also system is
> + * ready for completing firmware loading now. The maximum size of firmware in
> + * current distributions is about 2M bytes, so 10 secs should be enough.
> + */
> +static void fw_fallback_set_cache_timeout(void)
> +{
> +       old_timeout = loading_timeout;
> +       loading_timeout = 10;
> +}
> +
> +/* Restores the timeout to the value last configured during normal operation */
> +static void fw_fallback_set_default_timeout(void)
> +{
> +       loading_timeout =  old_timeout;
> +}
> +
>  static inline bool fw_sysfs_done(struct fw_priv *fw_priv)
>  {
>         return __fw_state_check(fw_priv, FW_STATUS_DONE);
> @@ -1206,6 +1225,8 @@ static int fw_sysfs_fallback(struct firmware *fw, const char *name,
>  }
>
>  static inline void kill_pending_fw_fallback_reqs(bool only_kill_custom) { }
> +static inline void fw_fallback_set_cache_timeout(void) { }
> +static inline void fw_fallback_set_default_timeout(void) { }
>
>  static inline int register_sysfs_loader(void)
>  {
> @@ -1752,7 +1773,6 @@ static void __device_uncache_fw_images(void)
>  static void device_cache_fw_images(void)
>  {
>         struct firmware_cache *fwc = &fw_cache;
> -       int old_timeout;
>         DEFINE_WAIT(wait);
>
>         pr_debug("%s\n", __func__);
> @@ -1760,16 +1780,7 @@ static void device_cache_fw_images(void)
>         /* cancel uncache work */
>         cancel_delayed_work_sync(&fwc->work);
>
> -       /*
> -        * use small loading timeout for caching devices' firmware
> -        * because all these firmware images have been loaded
> -        * successfully at lease once, also system is ready for
> -        * completing firmware loading now. The maximum size of
> -        * firmware in current distributions is about 2M bytes,
> -        * so 10 secs should be enough.
> -        */
> -       old_timeout = loading_timeout;
> -       loading_timeout = 10;
> +       fw_fallback_set_cache_timeout();
>
>         mutex_lock(&fw_lock);
>         fwc->state = FW_LOADER_START_CACHE;
> @@ -1779,7 +1790,7 @@ static void device_cache_fw_images(void)
>         /* wait for completion of caching firmware for all devices */
>         async_synchronize_full_domain(&fw_cache_domain);
>
> -       loading_timeout = old_timeout;
> +       fw_fallback_set_default_timeout();
>  }
>
>  /**
> --
> 2.16.2
>



-- 
Kees Cook
Pixel Security