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Subject[PATCH 12/15] ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump
Date
In systems with more than one processor it is desirable to look at the
per cpu trace buffers.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
---
kernel/trace/trace_kdb.c | 37 +++++++++++++++++++++++++++----------
1 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
index 44cbda2..7b8ecd7 100644
--- a/kernel/trace/trace_kdb.c
+++ b/kernel/trace/trace_kdb.c
@@ -17,7 +17,7 @@
#include "trace.h"
#include "trace_output.h"

-static void ftrace_dump_buf(int skip_lines)
+static void ftrace_dump_buf(int skip_lines, long cpu_file)
{
/* use static because iter can be a bit big for the stack */
static struct trace_iterator iter;
@@ -44,13 +44,20 @@ static void ftrace_dump_buf(int skip_lines)
iter.iter_flags |= TRACE_FILE_LAT_FMT;
iter.pos = -1;

- for_each_tracing_cpu(cpu) {
- iter.buffer_iter[cpu] =
+ if (cpu_file == TRACE_PIPE_ALL_CPU) {
+ for_each_tracing_cpu(cpu) {
+ iter.buffer_iter[cpu] =
ring_buffer_read_prepare(iter.tr->buffer, cpu);
- ring_buffer_read_start(iter.buffer_iter[cpu]);
- tracing_iter_reset(&iter, cpu);
+ ring_buffer_read_start(iter.buffer_iter[cpu]);
+ tracing_iter_reset(&iter, cpu);
+ }
+ } else {
+ iter.cpu_file = cpu_file;
+ iter.buffer_iter[cpu_file] =
+ ring_buffer_read_prepare(iter.tr->buffer, cpu_file);
+ ring_buffer_read_start(iter.buffer_iter[cpu_file]);
+ tracing_iter_reset(&iter, cpu_file);
}
-
if (!trace_empty(&iter))
trace_find_next_entry_inc(&iter);
while (!trace_empty(&iter)) {
@@ -91,9 +98,10 @@ out:
static int kdb_ftdump(int argc, const char **argv)
{
int skip_lines = 0;
+ long cpu_file;
char *cp;

- if (argc > 1)
+ if (argc > 2)
return KDB_ARGCOUNT;

if (argc) {
@@ -102,8 +110,17 @@ static int kdb_ftdump(int argc, const char **argv)
skip_lines = 0;
}

+ if (argc == 2) {
+ cpu_file = simple_strtol(argv[2], &cp, 0);
+ if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
+ !cpu_online(cpu_file))
+ return KDB_BADINT;
+ } else {
+ cpu_file = TRACE_PIPE_ALL_CPU;
+ }
+
kdb_trap_printk++;
- ftrace_dump_buf(skip_lines);
+ ftrace_dump_buf(skip_lines, cpu_file);
kdb_trap_printk--;

return 0;
@@ -111,8 +128,8 @@ static int kdb_ftdump(int argc, const char **argv)

static __init int kdb_ftrace_register(void)
{
- kdb_register_repeat("ftdump", kdb_ftdump, "", "Dump ftrace log",
- 0, KDB_REPEAT_NONE);
+ kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
+ "Dump ftrace log", 0, KDB_REPEAT_NONE);
return 0;
}

--
1.6.4.rc1


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