Re: [PATCH RFT] i2c: designware: ratelimit 'transfer when suspended' errors

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, Apr 24, 2019 at 06:16:32PM +0200, Wolfram Sang wrote:
> There are two problems with dev_err() here. One: It is not ratelimited.
> Two: We don't see which driver tried to transfer something with a
> suspended adapter. Switch to dev_WARN_ONCE to fix both issues. Drawback
> is that we don't see if multiple drivers are trying to transfer while
> suspended. They need to be discovered one after the other now. This is
> better than a high CPU load because a really broken driver might try to
> resend endlessly.
> 

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Link: https://bugs.archlinux.org/task/62391
> Fixes: 275154155538 ("i2c: designware: Do not allow i2c_dw_xfer() calls while suspended")
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> 
> skdnik: Would you be so kind and test this patch? I can only build-test here.
> 
> I have a prototype to fix the similar issue in the core, but this needs more
> testing first, so I am sending this one out already.
> 
>  drivers/i2c/busses/i2c-designware-master.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
> index bb8e3f149979..d464799e40a3 100644
> --- a/drivers/i2c/busses/i2c-designware-master.c
> +++ b/drivers/i2c/busses/i2c-designware-master.c
> @@ -426,8 +426,7 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
>  
>  	pm_runtime_get_sync(dev->dev);
>  
> -	if (dev->suspended) {
> -		dev_err(dev->dev, "Error %s call while suspended\n", __func__);
> +	if (dev_WARN_ONCE(dev->dev, dev->suspended, "Transfer while suspended\n")) {
>  		ret = -ESHUTDOWN;
>  		goto done_nolock;
>  	}
> -- 
> 2.11.0
> 

-- 
With Best Regards,
Andy Shevchenko