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Date: Sun, 16 Nov 2008 18:36:25 -0800 From: "Steven Noonan" <steven@...inklabs.net> To: "Frederic Weisbecker" <fweisbec@...il.com> Cc: "Ingo Molnar" <mingo@...e.hu>, "Steven Rostedt" <rostedt@...dmis.org>, "Linux Kernel" <linux-kernel@...r.kernel.org> Subject: Re: [PATCH 2/3] tracing/ftrace: make nop tracer using tracer flags On Sun, Nov 16, 2008 at 6:19 PM, Frederic Weisbecker <fweisbec@...il.com> wrote: > Impact: give an example on how to use specific tracer flags > > This patch propose to use the nop tracer to provide an > example for using the tracer's custom flags implementation. > > Signed-off-by: Frederic Weisbecker <fweisbec@...il.com> > --- > kernel/trace/trace_nop.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 48 insertions(+), 0 deletions(-) > > diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c > index 0e77415..1d8b4f8 100644 > --- a/kernel/trace/trace_nop.c > +++ b/kernel/trace/trace_nop.c > @@ -41,6 +41,52 @@ static void nop_trace_reset(struct trace_array *tr) > stop_nop_trace(tr); > } > > +#define TRACE_NOP_OPT_ACCEPT 0x1 > +#define TRACE_NOP_OPT_REFUSE 0x2 > +/* Options for the tracer (see trace_options file) */ > +static struct tracer_opt nop_opts[] = { > + /* Option that will be accepted by set_flag callback */ > + { TRACER_OPT(test_nop_accept, TRACE_NOP_OPT_ACCEPT) }, > + /* Option that will be refused by set_flag callback */ > + { TRACER_OPT(test_nop_refuse, TRACE_NOP_OPT_REFUSE) }, > + { } /* Always set the last empty entry */ > +}; > + > +static struct tracer_flags nop_flags = { > + /* You can check your flags value here when you want. */ > + .val = 0, /* By default: all flags disabled */ > + .opts = nop_opts > +}; I'd like these #defines and structs moved to just after the #includes, for cleanliness. > + > +/* It only serves as a signal handler and a callback to > + * accept or refuse tthe setting of a flag. > + * If you don't implement it, then the flag setting will be > + * automatically accepted. > + */ > +static int nop_set_flag(u32 old_flags, u32 bit, int set) > +{ > + /* > + * Note that you don't need to update nop_flags.val yourself. > + * The tracing Api will do it automatically if you return 0 > + */ > + if (bit == TRACE_NOP_OPT_ACCEPT) { > + printk(KERN_DEBUG "nop_test_accept flag set to %d: we accept." > + " Now cat trace_options to see the result\n", > + set); > + return 0; > + } > + > + if (bit == TRACE_NOP_OPT_REFUSE) { > + printk(KERN_DEBUG "nop_test_refuse flag set to %d: we refuse." > + "Now cat trace_options to see the result\n", > + set); > + return -EINVAL; > + } > + > + return 0; > +} > + > + > struct tracer nop_trace __read_mostly = > { > .name = "nop", > @@ -49,5 +95,7 @@ struct tracer nop_trace __read_mostly = > #ifdef CONFIG_FTRACE_SELFTEST > .selftest = trace_selftest_startup_nop, > #endif > + .flags = &nop_flags, > + .set_flag = nop_set_flag > }; > > -- > 1.5.2.5 > Other than the change noted above, I think it looks good. Acked-by: Steven Noonan <steven@...inklabs.net> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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