Re: [PATCH v2 0/9] encode the values directly in the table entry

[Wen Yang]

On 2024/3/21 23:21, Joel Granados wrote:
> On Sat, Mar 09, 2024 at 06:31:17PM +0800, wenyang.linux@xxxxxxxxxxx wrote:
> > From: Wen Yang <wenyang.linux@xxxxxxxxxxx>
> >
> > The boundary check of multiple modules uses these static variables (such as
> > two_five_five, n_65535, ue_int_max, etc), and they are also not changed.
> This message is a bit cryptic. I had to do a fair amount of research to
> get what you meant here. Having the context in front is OK with me, but
> I would add a bit more information so the reader does not have to go to
> the code and grep for the variables that you mean. Something like this:
> "When using a sysctl proc_handler that requires a boundary check (like
> proce_dointvec_minmax) it is common to use a const variable like n_65535
> in net/rxrpc/sysctl.c or OTHER EXAMPLES...). This is suboptimal because
> YOUR REASONS HERE"

Thanks a lot for your very considerate input – this is highly 
appreciated. We will revise the change message and send v3 later.

--
Best wishes,
Wen


> > Eric points out: "by turning .extra1 and .extra2 into longs instead of
> > keeping them as pointers and needing constants to be pointed at somewhere
> > ... The only people I can see who find a significant benefit by
> > consolidating all of the constants into one place are people who know how
> > to stomp kernel memory."
> I think it would be better to just link to the lore discussion.
>
> > This patch series achieves direct encoding values in table entries and still
> > maintains compatibility with existing extra1/extra2 pointers.
> > Afterwards, we can remove these unnecessary static variables progressively and
> > also gradually kill the shared const array.
> Two things:
> 1. Please name the const array: sysctl_vals
> 2. What is missing from this patchset to completely kill sysctl_vals?
>
> > Wen Yang (9):
> >    sysctl: support encoding values directly in the table entry
> >    kernel/sysctl-test: add some kunit test cases for min/max detection
> >    rxrpc: delete these unnecessary static variables n_65535, four,
> >      max_500, etc
> >    net: ipv6: delete these unnecessary static variables two_five_five and
> >      minus_one
> >    svcrdma: delete these unnecessary static variables min_ord, max_ord,
> >      etc
> >    sysctl: delete these unnecessary static variables i_zero and
> >      i_one_hundred
> >    epoll: delete these unnecessary static variables long_zero and
> >      long_max
> >    fs: inotify: delete these unnecessary static variables it_zero and
> >      it_int_max
> >    ucounts: delete these unnecessary static variables ue_zero and
> >      ue_int_max
> >
> >   fs/eventpoll.c                   |  19 +-
> >   fs/notify/inotify/inotify_user.c |  49 +++--
> >   include/linux/sysctl.h           | 108 ++++++++++-
> >   kernel/sysctl-test.c             | 300 +++++++++++++++++++++++++++++++
> >   kernel/sysctl.c                  |  61 +++++--
> >   kernel/ucount.c                  |   8 +-
> >   lib/test_sysctl.c                |  12 +-
> >   net/ipv6/addrconf.c              |  15 +-
> >   net/rxrpc/sysctl.c               | 169 ++++++++---------
> >   net/sunrpc/xprtrdma/svc_rdma.c   |  21 +--
> >   10 files changed, 571 insertions(+), 191 deletions(-)
> >
> > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> > Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> > Cc: Joel Granados <j.granados@xxxxxxxxxxx>
> > Cc: Christian Brauner <brauner@xxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> >
> > --
> > 2.25.1