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

From: Bjorn Andersson <[email-masked]>
Date: Thu, 26 Mar 2020 12:43:04 -0700

On Thu 26 Mar 07:01 PDT 2020, Suman Anna wrote:

> 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 <[email-masked]>
> >> ---
> >>  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?
> 

Look at the failure for ida_simple_get(), there we're past the setup of
rproc->dev.type, so the rproc_type->release function will be invoked as
we call put_device().

So if you move the initialization of rproc->dev up right after the
allocation of rproc we should be able to rely on that to clean up all
these for us.

Regards,
Bjorn

> 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
> >>
> 

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