Re: [PATCH 4/6] bus: fsl-mc: fsl-mc-allocator: Improve error reporting

[Uwe Kleine-König]

Hello,

On Thu, Jun 01, 2023 at 08:41:01AM -0700, Nathan Chancellor wrote:
> On Fri, Mar 10, 2023 at 11:41:26PM +0100, Uwe Kleine-König wrote:
> > Instead of silently returning an error in the remove callback (which yields
> > a generic and little informing error message), annotate each error path of
> > fsl_mc_resource_pool_remove_device() with an error message and return zero
> > in the remove callback to suppress the error message.
> > 
> > Note that changing the return value has no other effect than suppressing
> > the error message by the fsl_mc bus driver.
> > 
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> 
> I apologize if this has already been reported or fixed somewhere, I did
> a search of lore.kernel.org and did not find anything. This change as
> commit b3134039c5b3 ("bus: fsl-mc: fsl-mc-allocator: Improve error
> reporting") causes the following warning/error with clang:
> 
>   drivers/bus/fsl-mc/fsl-mc-allocator.c:108:12: error: variable 'mc_bus_dev' is uninitialized when used here [-Werror,-Wuninitialized]
>     108 |                 dev_err(&mc_bus_dev->dev, "resource mismatch\n");
>         |                          ^~~~~~~~~~
>   include/linux/dev_printk.h:144:44: note: expanded from macro 'dev_err'
>     144 |         dev_printk_index_wrap(_dev_err, KERN_ERR, dev, dev_fmt(fmt), ##__VA_ARGS__)
>         |                                                   ^~~
>   include/linux/dev_printk.h:110:11: note: expanded from macro 'dev_printk_index_wrap'
>     110 |                 _p_func(dev, fmt, ##__VA_ARGS__);                       \
>         |                         ^~~
>   drivers/bus/fsl-mc/fsl-mc-allocator.c:100:34: note: initialize the variable 'mc_bus_dev' to silence this warning
>     100 |         struct fsl_mc_device *mc_bus_dev;
>         |                                         ^
>         |                                          = NULL
>   1 error generated.
> 
> Should this be using mc_dev->dev or is there a different fix?
> 
> diff --git a/drivers/bus/fsl-mc/fsl-mc-allocator.c b/drivers/bus/fsl-mc/fsl-mc-allocator.c
> index 0ad68099684e..867ac3bbeae6 100644
> --- a/drivers/bus/fsl-mc/fsl-mc-allocator.c
> +++ b/drivers/bus/fsl-mc/fsl-mc-allocator.c
> @@ -105,7 +105,7 @@ static int __must_check fsl_mc_resource_pool_remove_device(struct fsl_mc_device
>  
>  	resource = mc_dev->resource;
>  	if (!resource || resource->data != mc_dev) {
> -		dev_err(&mc_bus_dev->dev, "resource mismatch\n");
> +		dev_err(&mc_dev->dev, "resource mismatch\n");
>  		goto out;
>  	}

Hmm, clang seems to be right, and I just confirmed that gcc
(arm-linux-gnueabihf-gcc (Debian 12.2.0-14) 12.2.0) doesn't emit a
warning. :-\

My approach would be:

diff --git a/drivers/bus/fsl-mc/fsl-mc-allocator.c b/drivers/bus/fsl-mc/fsl-mc-allocator.c
index 0ad68099684e..991273f956ce 100644
--- a/drivers/bus/fsl-mc/fsl-mc-allocator.c
+++ b/drivers/bus/fsl-mc/fsl-mc-allocator.c
@@ -103,14 +103,15 @@ static int __must_check fsl_mc_resource_pool_remove_device(struct fsl_mc_device
 	struct fsl_mc_resource *resource;
 	int error = -EINVAL;
 
+	mc_bus_dev = to_fsl_mc_device(mc_dev->dev.parent);
+	mc_bus = to_fsl_mc_bus(mc_bus_dev);
+
 	resource = mc_dev->resource;
 	if (!resource || resource->data != mc_dev) {
 		dev_err(&mc_bus_dev->dev, "resource mismatch\n");
 		goto out;
 	}
 
-	mc_bus_dev = to_fsl_mc_device(mc_dev->dev.parent);
-	mc_bus = to_fsl_mc_bus(mc_bus_dev);
 	res_pool = resource->parent_pool;
 	if (res_pool != &mc_bus->resource_pools[resource->type]) {
 		dev_err(&mc_bus_dev->dev, "pool mismatch\n");


Should I prepare a proper patch, or is it possible to squash this change
into b3134039c5b3cf879841e3ec84c8cbf7675554ec?

@Li Yang: Please advice.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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