linux-kernel - Re: [PATCH v2 03/14] sysctl: Add ctl_table_size to ctl_table

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Message-ID: <ZMgGWm4sT+VqDZ3u@kernel.org>
Date:   Mon, 31 Jul 2023 21:07:06 +0200
From:   Simon Horman <horms@...nel.org>
To:     Joel Granados <joel.granados@...il.com>
Cc:     mcgrof@...nel.org, Catalin Marinas <catalin.marinas@....com>,
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        Joel Granados <j.granados@...sung.com>
Subject: Re: [PATCH v2 03/14] sysctl: Add ctl_table_size to ctl_table_header

On Mon, Jul 31, 2023 at 08:30:34PM +0200, Simon Horman wrote:
> On Mon, Jul 31, 2023 at 09:17:17AM +0200, Joel Granados wrote:
> > The new ctl_table_size element will hold the size of the ctl_table
> > arrays contained in the ctl_table_header. This value should eventually
> > be passed by the callers to the sysctl register infrastructure. And
> > while this commit introduces the variable, it does not set nor use it
> > because that requires case by case considerations for each caller.
> > 
> > It provides two important things: (1) A place to put the
> > result of the ctl_table array calculation when it gets introduced for
> > each caller. And (2) the size that will be used as the additional
> > stopping criteria in the list_for_each_table_entry macro (to be added
> > when all the callers are migrated)
> > 
> > Signed-off-by: Joel Granados <j.granados@...sung.com>
> > ---
> >  include/linux/sysctl.h | 14 ++++++++++++--
> >  1 file changed, 12 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> > index 59d451f455bf..33252ad58ebe 100644
> > --- a/include/linux/sysctl.h
> > +++ b/include/linux/sysctl.h
> > @@ -159,12 +159,22 @@ struct ctl_node {
> >  	struct ctl_table_header *header;
> >  };
> >  
> > -/* struct ctl_table_header is used to maintain dynamic lists of
> > -   struct ctl_table trees. */
> > +/**
> > + * struct ctl_table_header - maintains dynamic lists of struct ctl_table trees
> > + * @ctl_table: pointer to the first element in ctl_table array
> > + * @ctl_table_size: number of elements pointed by @ctl_table
> > + * @used: The entry will never be touched when equal to 0.
> > + * @count: Upped every time something is added to @inodes and downed every time
> > + *         something is removed from inodes
> > + * @nreg: When nreg drops to 0 the ctl_table_header will be unregistered.
> > + * @rcu: Delays the freeing of the inode. Introduced with "unfuck proc_sysctl ->d_compare()"
> > + *
> > + */
> 
> Hi Joel,
> 
> Please consider also adding kernel doc entries for the other fields of
> struct ctl_table_header. According to ./scripts/kernel-doc -none
> they are:
> 
>   unregistering
>   ctl_table_arg
>   root
>   set
>   parent
>   node
>   inodes

Sorry, I now realise that I made the same comment on v1.
And I didn't see your response to that until after I wrote the above.

> 
> 
> >  struct ctl_table_header {
> >  	union {
> >  		struct {
> >  			struct ctl_table *ctl_table;
> > +			int ctl_table_size;
> >  			int used;
> >  			int count;
> >  			int nreg;
> > -- 
> > 2.30.2
> >