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Subject[60/85] tracing: Fix irqs-off tag display in syscall tracing
3.2.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "zhangwei(Jovi)" <jovi.zhangwei@huawei.com>

commit 11034ae9c20f4057a6127fc965906417978e69b2 upstream.

All syscall tracing irqs-off tags are wrong, the syscall enter entry doesn't
disable irqs.

[root@jovi tracing]#echo "syscalls:sys_enter_open" > set_event
[root@jovi tracing]# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 13/13 #P:2
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
irqbalance-513 [000] d... 56115.496766: sys_open(filename: 804e1a6, flags: 0, mode: 1b6)
irqbalance-513 [000] d... 56115.497008: sys_open(filename: 804e1bb, flags: 0, mode: 1b6)
sendmail-771 [000] d... 56115.827982: sys_open(filename: b770e6d1, flags: 0, mode: 1b6)

The reason is syscall tracing doesn't record irq_flags into buffer.
The proper display is:

[root@jovi tracing]#echo "syscalls:sys_enter_open" > set_event
[root@jovi tracing]# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 14/14 #P:2
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
irqbalance-514 [001] .... 46.213921: sys_open(filename: 804e1a6, flags: 0, mode: 1b6)
irqbalance-514 [001] .... 46.214160: sys_open(filename: 804e1bb, flags: 0, mode: 1b6)
<...>-920 [001] .... 47.307260: sys_open(filename: 4e82a0c5, flags: 80000, mode: 0)

Link: http://lkml.kernel.org/r/1365564393-10972-3-git-send-email-jovi.zhangwei@huawei.com

Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
kernel/trace/trace_syscalls.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -303,6 +303,8 @@ void ftrace_syscall_enter(void *ignore,
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
+ unsigned long irq_flags;
+ int pc;
int size;
int syscall_nr;

@@ -318,8 +320,11 @@ void ftrace_syscall_enter(void *ignore,

size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;

+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
event = trace_current_buffer_lock_reserve(&buffer,
- sys_data->enter_event->event.type, size, 0, 0);
+ sys_data->enter_event->event.type, size, irq_flags, pc);
if (!event)
return;

@@ -329,7 +334,8 @@ void ftrace_syscall_enter(void *ignore,

if (!filter_current_check_discard(buffer, sys_data->enter_event,
entry, event))
- trace_current_buffer_unlock_commit(buffer, event, 0, 0);
+ trace_current_buffer_unlock_commit(buffer, event,
+ irq_flags, pc);
}

void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
@@ -338,6 +344,8 @@ void ftrace_syscall_exit(void *ignore, s
struct syscall_metadata *sys_data;
struct ring_buffer_event *event;
struct ring_buffer *buffer;
+ unsigned long irq_flags;
+ int pc;
int syscall_nr;

syscall_nr = syscall_get_nr(current, regs);
@@ -350,8 +358,12 @@ void ftrace_syscall_exit(void *ignore, s
if (!sys_data)
return;

+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
event = trace_current_buffer_lock_reserve(&buffer,
- sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
+ sys_data->exit_event->event.type, sizeof(*entry),
+ irq_flags, pc);
if (!event)
return;

@@ -361,7 +373,8 @@ void ftrace_syscall_exit(void *ignore, s

if (!filter_current_check_discard(buffer, sys_data->exit_event,
entry, event))
- trace_current_buffer_unlock_commit(buffer, event, 0, 0);
+ trace_current_buffer_unlock_commit(buffer, event,
+ irq_flags, pc);
}

int reg_event_syscall_enter(struct ftrace_event_call *call)


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