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author | Frederic Weisbecker <fweisbec@gmail.com> | 2008-11-17 19:26:30 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-11-18 11:10:59 +0100 |
commit | 0619faf657806b943e6acf51f60f1cd023a96c78 (patch) | |
tree | 4b7a6e13ff4851a8719189d27c3ce8d3e91ac62d /kernel/trace/trace_nop.c | |
parent | adf9f19574334c9a29a2bc956009fcac7edf1a6b (diff) | |
download | kernel_samsung_smdk4412-0619faf657806b943e6acf51f60f1cd023a96c78.zip kernel_samsung_smdk4412-0619faf657806b943e6acf51f60f1cd023a96c78.tar.gz kernel_samsung_smdk4412-0619faf657806b943e6acf51f60f1cd023a96c78.tar.bz2 |
tracing/ftrace: make nop tracer using tracer flags
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.
V2: replace structures and defines just after the headers includes for
cleanliness.
V3: replace defines by enum values.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Noonan <steven@uplinklabs.net>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/trace_nop.c')
-rw-r--r-- | kernel/trace/trace_nop.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c index 0e77415..b9767ac 100644 --- a/kernel/trace/trace_nop.c +++ b/kernel/trace/trace_nop.c @@ -12,6 +12,27 @@ #include "trace.h" +/* Our two options */ +enum { + TRACE_NOP_OPT_ACCEPT = 0x1, + 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 a 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 +}; + static struct trace_array *ctx_trace; static void start_nop_trace(struct trace_array *tr) @@ -41,6 +62,35 @@ static void nop_trace_reset(struct trace_array *tr) stop_nop_trace(tr); } +/* 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 +99,7 @@ struct tracer nop_trace __read_mostly = #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_nop, #endif + .flags = &nop_flags, + .set_flag = nop_set_flag }; |