linux-kernel - Re: [PATCH v2 4/4] riscv: Convert relocation iterator to do-while

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Message-ID: <ZZcIthn20O1l1DDL@ghost>
Date: Thu, 4 Jan 2024 11:36:22 -0800
From: Charlie Jenkins <charlie@...osinc.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Palmer Dabbelt <palmer@...osinc.com>,
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kernel test robot <lkp@...el.com>,
	Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH v2 4/4] riscv: Convert relocation iterator to do-while

On Thu, Jan 04, 2024 at 03:35:55PM +0300, Dan Carpenter wrote:
> On Wed, Jan 03, 2024 at 12:22:03PM -0800, Charlie Jenkins wrote:
> > Use a do-while loop to iterate through relocation entries to prevent
> > curr_type from being marked as uninitialized.
> > 
> > Signed-off-by: Charlie Jenkins <charlie@...osinc.com>
> > Fixes: d8792a5734b0 ("riscv: Safely remove entries from relocation list")
> > Reported-by: kernel test robot <lkp@...el.com>
> > Reported-by: Dan Carpenter <error27@...il.com>
> > Closes: https://lore.kernel.org/r/202312130859.wnkuzVWY-lkp@intel.com/
> > ---
> >  arch/riscv/kernel/module.c | 26 +++++++++++++++++++++-----
> >  1 file changed, 21 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> > index ceb0adb38715..581e425686ab 100644
> > --- a/arch/riscv/kernel/module.c
> > +++ b/arch/riscv/kernel/module.c
> > @@ -633,15 +633,31 @@ process_accumulated_relocations(struct module *me,
> >  					  bucket_iter->bucket, node) {
> >  			buffer = 0;
> >  			location = rel_head_iter->location;
> > -			list_for_each_entry_safe(rel_entry_iter,
> > -						 rel_entry_iter_tmp,
> > -						 rel_head_iter->rel_entry,
> > -						 head) {
> > +			rel_entry_iter =
> > +				list_first_entry(rel_head_iter->rel_entry,
> > +						 typeof(*rel_entry_iter), head);
> > +			rel_entry_iter_tmp =
> > +				list_next_entry(rel_entry_iter, head);
> > +
> > +			/*
> > +			 * Iterate through all relocation entries that share
> > +			 * this location. This uses a do-while loop instead of
> > +			 * list_for_each_entry_safe since it is known that there
> > +			 * is at least one entry and curr_type needs to be the
> > +			 * value of the last entry when the loop exits.
> > +			 */
> 
> I know that I reported this static checker and all, but actually after
> reading this comment, I think we should stay with original code.  So
> long as we know the list has "least one entry" which we do then the
> original code worked fine.
> 
> To be honest, I probably would not have even reported this static
> checker warning except that I saw there were some other issues and
> thought "Eh, why not throw this warning in as well, in case the list
> can be empty."

That makes sense, I will drop that patch.

- Charlie

> 
> The other three patches look good.
> 
> regards,
> dan carpenter
>