[tip:perf/core] ksym_tracer: Extract trace entry from struct trace_ksym

tip-bot for Li Zefan
2009-11-21T13:34:37Z

Commit-ID: db59504d89db1462a5281fb55b1d962cb74a398f
Gitweb: http://git.kernel.org/tip/db59504d89db1462a5281fb55b1d962cb74a398f
Author: Li Zefan <lizf@cn.fujitsu.com>
AuthorDate: Tue, 7 Jul 2009 13:52:36 +0800
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 10 Jul 2009 11:59:40 +0200

ksym_tracer: Extract trace entry from struct trace_ksym

struct trace_ksym is used as an entry in hbp list, and is also
used as trace_entry stored in ring buffer.

This is not necessary and is a waste of memory in ring buffer.

There is also a bug that dereferencing field->ksym_hbp in
ksym_trace_output() can be invalid.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2A4.4050007@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/trace/trace.h | 13 ++++---------
kernel/trace/trace_ksym.c | 26 ++++++++++++++++++--------
2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7d5cc37..ff1ef41 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -215,17 +215,12 @@ struct syscall_trace_exit {
#define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy"
extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);

-struct trace_ksym {
+struct ksym_trace_entry {
struct trace_entry ent;
- struct hw_breakpoint *ksym_hbp;
- unsigned long ksym_addr;
unsigned long ip;
-#ifdef CONFIG_PROFILE_KSYM_TRACER
- unsigned long counter;
-#endif
- struct hlist_node ksym_hlist;
+ unsigned char type;
char ksym_name[KSYM_NAME_LEN];
- char p_name[TASK_COMM_LEN];
+ char cmd[TASK_COMM_LEN];
};

/*
@@ -343,7 +338,7 @@ extern void __ftrace_bad_type(void);
TRACE_SYSCALL_ENTER); \
IF_ASSIGN(var, ent, struct syscall_trace_exit, \
TRACE_SYSCALL_EXIT); \
- IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM); \
+ IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\
__ftrace_bad_type(); \
} while (0)

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index eef97e7..085ff05 100644
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -37,6 +37,15 @@
#define KSYM_TRACER_OP_LEN 3 /* rw- */
#define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1)

+struct trace_ksym {
+ struct hw_breakpoint *ksym_hbp;
+ unsigned long ksym_addr;
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+ unsigned long counter;
+#endif
+ struct hlist_node ksym_hlist;
+};
+
static struct trace_array *ksym_trace_array;

static unsigned int ksym_filter_entry_count;
@@ -71,7 +80,7 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
{
struct ring_buffer_event *event;
struct trace_array *tr;
- struct trace_ksym *entry;
+ struct ksym_trace_entry *entry;
int pc;

if (!ksym_tracing_enabled)
@@ -85,11 +94,12 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
if (!event)
return;

- entry = ring_buffer_event_data(event);
+ entry = ring_buffer_event_data(event);
+ entry->ip = instruction_pointer(regs);
+ entry->type = hbp->info.type;
strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);
- entry->ksym_hbp = hbp;
- entry->ip = instruction_pointer(regs);
- strlcpy(entry->p_name, current->comm, TASK_COMM_LEN);
+ strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);
+
#ifdef CONFIG_PROFILE_KSYM_TRACER
ksym_collect_stats(hbp->info.address);
#endif /* CONFIG_PROFILE_KSYM_TRACER */
@@ -380,7 +390,7 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
{
struct trace_entry *entry = iter->ent;
struct trace_seq *s = &iter->seq;
- struct trace_ksym *field;
+ struct ksym_trace_entry *field;
char str[KSYM_SYMBOL_LEN];
int ret;

@@ -389,12 +399,12 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)

trace_assign_type(field, entry);

- ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->p_name,
+ ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->cmd,
entry->pid, iter->cpu, field->ksym_name);
if (!ret)
return TRACE_TYPE_PARTIAL_LINE;

- switch (field->ksym_hbp->info.type) {
+ switch (field->type) {
case HW_BREAKPOINT_WRITE:
ret = trace_seq_printf(s, " W ");
break;