Re: [PATCH v2] rcu: ensure kernel/rcu/rcu.h can be sourced/used stand-alone

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Wed, Feb 19, 2014 at 09:02:13PM -0500, Paul Gortmaker wrote:
> [Re: [PATCH v2] rcu: ensure kernel/rcu/rcu.h can be sourced/used stand-alone] On 19/02/2014 (Wed 17:53) Paul E. McKenney wrote:
> 
> > On Wed, Feb 19, 2014 at 02:33:27PM -0500, Paul Gortmaker wrote:
> > > The kbuild test bot uncovered an implicit dependence on the
> > > trace header being present before rcu.h in ia64 allmodconfig
> > > that looks like this:
> > > 
> > > In file included from kernel/ksysfs.c:22:0:
> > > kernel/rcu/rcu.h: In function '__rcu_reclaim':
> > > kernel/rcu/rcu.h:107:3: error: implicit declaration of function 'trace_rcu_invoke_kfree_callback' [-Werror=implicit-function-declaration]
> > > kernel/rcu/rcu.h:112:3: error: implicit declaration of function 'trace_rcu_invoke_callback' [-Werror=implicit-function-declaration]
> > > cc1: some warnings being treated as errors
> > > 
> > > Looking at other rcu.h users, we can find that they all
> > > were sourcing the trace header in advance of rcu.h itself,
> > > as seen in the context of this diff.  There were also some
> > > inconsistencies as to whether it was or wasn't sourced based
> > > on the parent tracing Kconfig.
> > > 
> > > Rather than "fix" it at each use site, and have inconsistent
> > > use based on whether "#ifdef CONFIG_RCU_TRACE" was used or not,
> > > lets just source the trace header just once, in the actual consumer
> > > of it, which is rcu.h itself.  We include it unconditionally, as
> > > build testing shows us that is a hard requirement for some files.
> > > 
> > > Reported-by: kbuild test robot <fengguang.wu@intel.com>
> > > Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> > 
> > Queued for 3.16, thank you, Paul!
> 
> Thanks!
> 
> I'm assuming you meant 3.15 -- unless of course you are allowing
> for an insurance policy for me possibly breaking the build.  ;)

Well, it does seem to be doing better in testing.  ;-)

I split off the stuff for the 3.15 merge window a few days back, but
if the lack of this patch is causing a problem, I could be talked into
slipping it in.

							Thanx, Paul

> P.
> --
> 
> > 
> > 							Thanx, Paul
> > 
> > > ---
> > > 
> > > [v2: move the #include <trace/events/rcu.h> outside of the scope
> > >  of #ifdef CONFIG_RCU_TRACE so it is unconditionally included.]
> > > 
> > >  kernel/rcu/rcu.h    | 1 +
> > >  kernel/rcu/srcu.c   | 2 --
> > >  kernel/rcu/tiny.c   | 4 ----
> > >  kernel/rcu/tree.c   | 2 --
> > >  kernel/rcu/update.c | 1 -
> > >  5 files changed, 1 insertion(+), 9 deletions(-)
> > > 
> > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
> > > index 1bd787fddcb2..3d2a037332b2 100644
> > > --- a/kernel/rcu/rcu.h
> > > +++ b/kernel/rcu/rcu.h
> > > @@ -23,6 +23,7 @@
> > >  #ifndef __LINUX_RCU_H
> > >  #define __LINUX_RCU_H
> > > 
> > > +#include <trace/events/rcu.h>
> > >  #ifdef CONFIG_RCU_TRACE
> > >  #define RCU_TRACE(stmt) stmt
> > >  #else /* #ifdef CONFIG_RCU_TRACE */
> > > diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
> > > index 5db7e9272d37..8e66b05bfd82 100644
> > > --- a/kernel/rcu/srcu.c
> > > +++ b/kernel/rcu/srcu.c
> > > @@ -36,8 +36,6 @@
> > >  #include <linux/delay.h>
> > >  #include <linux/srcu.h>
> > > 
> > > -#include <trace/events/rcu.h>
> > > -
> > >  #include "rcu.h"
> > > 
> > >  /*
> > > diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
> > > index 53b95bbf4abb..d9efcc13008c 100644
> > > --- a/kernel/rcu/tiny.c
> > > +++ b/kernel/rcu/tiny.c
> > > @@ -37,10 +37,6 @@
> > >  #include <linux/prefetch.h>
> > >  #include <linux/ftrace_event.h>
> > > 
> > > -#ifdef CONFIG_RCU_TRACE
> > > -#include <trace/events/rcu.h>
> > > -#endif /* #else #ifdef CONFIG_RCU_TRACE */
> > > -
> > >  #include "rcu.h"
> > > 
> > >  /* Forward declarations for tiny_plugin.h. */
> > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > > index c7a00dbe768b..351faba48b91 100644
> > > --- a/kernel/rcu/tree.c
> > > +++ b/kernel/rcu/tree.c
> > > @@ -58,8 +58,6 @@
> > >  #include <linux/suspend.h>
> > > 
> > >  #include "tree.h"
> > > -#include <trace/events/rcu.h>
> > > -
> > >  #include "rcu.h"
> > > 
> > >  MODULE_ALIAS("rcutree");
> > > diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
> > > index fd0d5b5b8e7c..4c0a9b0af469 100644
> > > --- a/kernel/rcu/update.c
> > > +++ b/kernel/rcu/update.c
> > > @@ -49,7 +49,6 @@
> > >  #include <linux/module.h>
> > > 
> > >  #define CREATE_TRACE_POINTS
> > > -#include <trace/events/rcu.h>
> > > 
> > >  #include "rcu.h"
> > > 
> > > -- 
> > > 1.8.5.2
> > > 
> > 
>