diff options
Diffstat (limited to 'kernel/trace/trace_nop.c')
-rw-r--r-- | kernel/trace/trace_nop.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c new file mode 100644 index 00000000000..b9767acd30a --- /dev/null +++ b/kernel/trace/trace_nop.c @@ -0,0 +1,105 @@ +/* + * nop tracer + * + * Copyright (C) 2008 Steven Noonan <steven@uplinklabs.net> + * + */ + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/debugfs.h> +#include <linux/ftrace.h> + +#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) +{ + /* Nothing to do! */ +} + +static void stop_nop_trace(struct trace_array *tr) +{ + /* Nothing to do! */ +} + +static int nop_trace_init(struct trace_array *tr) +{ + int cpu; + ctx_trace = tr; + + for_each_online_cpu(cpu) + tracing_reset(tr, cpu); + + start_nop_trace(tr); + return 0; +} + +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", + .init = nop_trace_init, + .reset = nop_trace_reset, +#ifdef CONFIG_FTRACE_SELFTEST + .selftest = trace_selftest_startup_nop, +#endif + .flags = &nop_flags, + .set_flag = nop_set_flag +}; + |