On Fri, 11 Jul 2014 08:12:40 -0700
"Paul E. McKenney" <[email protected]> wrote:
> On Fri, Jul 11, 2014 at 01:38:12PM +0200, Ard Biesheuvel wrote:
> > Commit f7f7bac9cb1c ("rcu: Have the RCU tracepoints use the
> > tracepoint_string
> > infrastructure") unconditionally populates the __tracepoint_str input
> > section,
> > but this section is not assigned an output section if CONFIG_TRACING is not
> > set.
> > This results in the __tracepoint_str turning up in unexpected places, i.e.,
> > after _edata.
> >
> > Signed-off-by: Ard Biesheuvel <[email protected]>
> > Cc: [email protected]
> > Cc: [email protected]
> > Cc: [email protected]
>
> If you get a Reviewed-by from Steven Rostedt, I will be happy to queue
> this one.
I'm fine with it, but it should add a comment.
>
> Thanx, Paul
>
> > ---
> > kernel/rcu/tree.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> > index f1ba77363fbb..ac1984149eb5 100644
> > --- a/kernel/rcu/tree.c
> > +++ b/kernel/rcu/tree.c
> > @@ -79,9 +79,16 @@ static struct lock_class_key rcu_fqs_class[RCU_NUM_LVLS];
> > * the tracing userspace tools to be able to decipher the string
> > * address to the matching string.
> > */
> > +#ifdef CONFIG_TRACING
/*
* When tracing is enabled, DEFINE_TPS() will export the string to
* userspace via the tracing debugfs directory. This allows userspace
* tools to read the binary tracepoints that reference the pointer
* to the string and not the string itself.
*/
> > +#define DEFINE_TPS(sname) \
> > +static const char *tp_##sname##_varname __used __tracepoint_string =
> > sname##_varname;
> > +#else
> > +#define DEFINE_TPS(sname)
> > +#endif
Also, perhaps we should call it:
DEFINE_RCU_TPS()
Other than that, I'm fine with the patch.
I'll review v2 ;-)
-- Steve
> > +
> > #define RCU_STATE_INITIALIZER(sname, sabbr, cr) \
> > static char sname##_varname[] = #sname; \
> > -static const char *tp_##sname##_varname __used __tracepoint_string =
> > sname##_varname; \
> > +DEFINE_TPS(sname) \
> > struct rcu_state sname##_state = { \
> > .level = { &sname##_state.node[0] }, \
> > .call = cr, \
> > --
> > 1.8.3.2
> >
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