Messages in this thread | | | Date | Fri, 11 Jul 2014 20:09:26 +0200 | Subject | Re: [PATCH] rcu: define tracepoint strings only if CONFIG_TRACING is set | From | Ard Biesheuvel <> |
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On 11 July 2014 17:40, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > On 11 July 2014 17:30, Steven Rostedt <rostedt@goodmis.org> wrote: >> On Fri, 11 Jul 2014 08:12:40 -0700 >> "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> 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 <ard.biesheuvel@linaro.org> >>> > Cc: rostedt@goodmis.org >>> > Cc: dipankar@in.ibm.com >>> > Cc: paulmck@linux.vnet.ibm.com >>> >>> 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. >> */ >> >>
Ehm, actually, a comment to that effect is already right there in the file. Would you still like me to add this additional comment?
>>> > +#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 ;-) >> > > Thanks gents, v2 coming up. > > -- > Ard. > > >>> > + >>> > #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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