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

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Message-ID: <2089a4a8-d5e4-e4f5-e7bc-7d053f654204@ti.com>
Date:   Thu, 26 Mar 2020 09:01:34 -0500
From:   Suman Anna <s-anna@...com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
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

Hi Bjorn,

On 3/26/20 12:42 AM, Bjorn Andersson wrote:
> 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.

Agreed, that's better functions to use for this.

> 
>> +	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?

Not sure I understand. I don't see any release function, all failure
paths in rproc_alloc() directly unwind the previous operations. You mean
move this to before the alloc for rproc structure, something similar to
what we are doing with firmware?

regards
Suman


> 
> 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
>>