Re: [PATCH V1] rcu-tasks: Fix build error

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Feb 21, 2023 at 04:49:17PM +0530, Srinivasarao Pathipati wrote:
> 
> On 2/21/2023 4:07 PM, Greg KH wrote:
> > On Tue, Feb 21, 2023 at 02:57:15PM +0530, Srinivasarao Pathipati wrote:
> > > On 2/21/2023 12:24 AM, Greg KH wrote:
> > > > On Mon, Feb 20, 2023 at 11:43:59PM +0530, Srinivasarao Pathipati wrote:
> > > > > Making show_rcu_tasks_rude_gp_kthread() function as 'inline' to
> > > > > fix below compilation error.
> > > > > This is applicable to only 5.10 kernels as code got modified
> > > > > in latest kernels.
> > > > > 
> > > > >    In file included from kernel/rcu/update.c:579:0:
> > > > >    kernel/rcu/tasks.h:710:13: error: ‘show_rcu_tasks_rude_gp_kthread’ defined but not used [-Werror=unused-function]
> > > > >     static void show_rcu_tasks_rude_gp_kthread(void) {}
> > > > > 
> > > > > Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com>
> > > > > ---
> > > > >    kernel/rcu/tasks.h | 2 +-
> > > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > > > 
> > > > > diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
> > > > > index 8b51e6a..53ddb4e 100644
> > > > > --- a/kernel/rcu/tasks.h
> > > > > +++ b/kernel/rcu/tasks.h
> > > > > @@ -707,7 +707,7 @@ static void show_rcu_tasks_rude_gp_kthread(void)
> > > > >    #endif /* #ifndef CONFIG_TINY_RCU */
> > > > >    #else /* #ifdef CONFIG_TASKS_RUDE_RCU */
> > > > > -static void show_rcu_tasks_rude_gp_kthread(void) {}
> > > > > +static inline void show_rcu_tasks_rude_gp_kthread(void) {}
> > > > >    #endif /* #else #ifdef CONFIG_TASKS_RUDE_RCU */
> > > > >    ////////////////////////////////////////////////////////////////////////
> > > > > -- 
> > > > > 2.7.4
> > > > > 
> > > > What commit id caused this problem?
> > > commit  (8344496e8b49c4122c1808d6cd3f8dc71bccb595 rcu-tasks: Conditionally
> > > compile show_rcu_tasks_gp_kthreads()) introduced this issue
> > So this has been around for a very very long time.
> > 
> > Why is this suddenly an issue now, almost 3 years later?  What changed
> > to cause this to become an issue?
> > 
> > And please put this information in the changelog text.
> 
>  We observed this issue on Android kernels with arch=UM  after picking this
> patch (3fe617ccafd6f5bb33c2391d6f4eeb41c1fd0151 Enable '-Werror' by default
> for all kernel builds ) recently into Android kernels.

But that commit is NOT in the 5.10.y tree, so why would we care about
this problem in the 5.10.y tree?

confused,

greg k-h