On Tue, Mar 15, 2022 at 5:52 PM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote:
>
> On Tue, Mar 15, 2022 at 09:55:49AM +0100, Lukas Bulwahn wrote:
> > Commit 9c7ef4c30f12 ("srcu: Make Tree SRCU able to operate without snp_node
> > array") initializes the local variable sdp differently depending on the
> > srcu's state in srcu_gp_start().
> >
> > Hence, the initialization of sdp with the variable definition is not used
> > before its second initialization.
> >
> > Drop the needless initialization in srcu_gp_start() to have clear code.
> >
> > No functional change. Some changes in the resulting object code due to
> > various rearrangements by the compiler.
> >
> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> > ---
> > Paul, please pick this minor non-urgent clean-up patch.
>
> Good eyes, thank you!
>
> I have pulled this in for testing and review. If things go will,
> I expect to push it into the v5.19 merge window (that is, not the one
> that will likely open next week, but the one after that).
>
> As usual, I could not resist wordsmithing the commit log. Could you
> please check out the wordsmithed version below to make sure that I did
> not mess something up?
>
Wordsmithing was good. I am basically still reading in your versions
what I intended to state with my commit message; +1!
And of course, you are a native speaker; so, I trust your English is
better than mine.
Lukas
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit a0c59d99e87c52d6832e1ad39421b4a4386cdfd6
> Author: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> Date: Tue Mar 15 09:55:49 2022 +0100
>
> srcu: Drop needless initialization of sdp in srcu_gp_start()
>
> Commit 9c7ef4c30f12 ("srcu: Make Tree SRCU able to operate without
> snp_node array") initializes the local variable sdp differently depending
> on the srcu's state in srcu_gp_start(). Either way, this initialization
> overwrites the value used when sdp is defined.
>
> This commit therefore drops this pointless definition-time initialization.
> Although there is no functional change, compiler code generation may
> be affected.
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
>
> diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
> index e78b1c7929d6..3bc8267c5d0b 100644
> --- a/kernel/rcu/srcutree.c
> +++ b/kernel/rcu/srcutree.c
> @@ -609,7 +609,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock);
> */
> static void srcu_gp_start(struct srcu_struct *ssp)
> {
> - struct srcu_data *sdp = this_cpu_ptr(ssp->sda);
> + struct srcu_data *sdp;
> int state;
>
> if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
