linux-kernel - Re: [PATCH 2/7] remoteproc: use a local copy for the name field

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Date:   Wed, 25 Mar 2020 22:42:34 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Suman Anna <s-anna@...com>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lokesh Vutla <lokeshvutla@...com>,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/7] remoteproc: use a local copy for the name field

On Tue 24 Mar 13:18 PDT 2020, Suman Anna wrote:

> The current name field used in the remoteproc structure is simply
> a pointer to a name field supplied during the rproc_alloc() call.
> The pointer passed in by remoteproc drivers during registration is
> typically a dev_name pointer, but it is possible that the pointer
> will no longer remain valid if the devices themselves were created
> at runtime like in the case of of_platform_populate(), and were
> deleted upon any failures within the respective remoteproc driver
> probe function.
> 
> So, allocate and maintain a local copy for this name field to
> keep it agnostic of the logic used in the remoteproc drivers.
> 
> Signed-off-by: Suman Anna <s-anna@...com>
> ---
>  drivers/remoteproc/remoteproc_core.c | 9 ++++++++-
>  include/linux/remoteproc.h           | 2 +-
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index aca6d022901a..6e0b91fa6f11 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1989,6 +1989,7 @@ static void rproc_type_release(struct device *dev)
>  
>  	kfree(rproc->firmware);
>  	kfree(rproc->ops);
> +	kfree(rproc->name);
>  	kfree(rproc);
>  }
>  
> @@ -2061,7 +2062,13 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
>  	}
>  
>  	rproc->firmware = p;
> -	rproc->name = name;
> +	rproc->name = kstrdup(name, GFP_KERNEL);

Let's use kstrdup_const() instead here (and kfree_const() instead of
kfree()), so that the cases where we are passed a constant we won't
create a duplicate on the heap.

And the "name" in struct rproc can remain const.

> +	if (!rproc->name) {
> +		kfree(p);
> +		kfree(rproc->ops);
> +		kfree(rproc);
> +		return NULL;

Perhaps we can rearrange the hunks here slightly and get to a point
where we can rely on the release function earlier?

Regards,
Bjorn

> +	}
>  	rproc->priv = &rproc[1];
>  	rproc->auto_boot = true;
>  	rproc->elf_class = ELFCLASS32;
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index ddce7a7775d1..77788a4bb94e 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -490,7 +490,7 @@ struct rproc_dump_segment {
>  struct rproc {
>  	struct list_head node;
>  	struct iommu_domain *domain;
> -	const char *name;
> +	char *name;
>  	char *firmware;
>  	void *priv;
>  	struct rproc_ops *ops;
> -- 
> 2.23.0
>