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Message-ID: <56CF319B.8060806@gmail.com>
Date: Fri, 26 Feb 2016 01:53:47 +0900
From: Taeung Song <treeze.taeung@...il.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
Lai Jiangshan <jiangshanlai@...il.com>
Subject: Re: [PATCH RESEND 1/3] tracing/syscalls: Rename variable 'nr' to
'syscall_nr'
Hi, Steven
On 02/26/2016 12:47 AM, Steven Rostedt wrote:
> On Fri, 26 Feb 2016 00:24:18 +0900
> Taeung Song <treeze.taeung@...il.com> wrote:
>
>> There is a problem about duplicated variable name
>> for system call number and a argument of some
>> system call. I found this problem when I tested
>> perf-script with python script as below.
>>
>> # perf record -e syscalls:*
>> # perf script -g python
>> # perf script -s perf-script.py
>> File "perf-script.py", line 8694
>> def syscalls__sys_enter_io_getevents(event_name, context, common_cpu,
>> SyntaxError: duplicate argument 'nr' in function definition
>> Error running python script perf-script.py
>>
>> As above, problems about duplicated argument occurred
>> when processing sys_enter_io_getevent() and sys_enter_io_submit().
>> Because the two system calls have a argument 'nr' as below.
>>
>> int io_getevents(aio_context_t ctx_id, long min_nr, long nr,
>> struct io_event *events, struct timespec *timeout);
>>
>> int io_submit(aio_context_t ctx_id, long nr, struct iocb **iocbpp);
>>
>> So rename a variable 'nr' to 'syscall_nr' for system call number
>> in print_syscall_enter().
>
> WTF, how does changing the kernel fix a user space python generation
> bug?
>
The underlying cause of this problem is not because of
the python script. This problem have relevance to tracing/syscalls
as below.
# cat
/sys/kernel/debug/tracing/events/syscalls/sys_enter_io_getevents/format
name: sys_enter_io_getevents
ID: 739
format:
field:unsigned short common_type; offset:0;size:2;signed:0;
field:unsigned char common_flags; offset:2;size:1;signed:0;
field:unsigned char common_preempt_count; offset:3;size:1;signed:0;
field:int common_pid; offset:4;size:4;signed:1;
field:int nr; offset:8;size:4;signed:1;
field:aio_context_t ctx_id; offset:16;size:8;signed:0;
field:long min_nr; offset:24;size:8;signed:0;
field:long nr; offset:32;size:8;signed:0;
field:struct io_event * events; offset:40;size:8;signed:0;
field:struct timespec * timeout; offset:48;size:8;signed:0;
print fmt: "ctx_id: 0x%08lx, min_nr: 0x%08lx, nr: 0x%08lx, events:
0x%08lx, timeout: 0x%08lx", ((unsigned long)(REC->ctx_id)), ((unsigned
long)(REC->min_nr)), ((unsigned long)(REC->nr)), ((unsigned
long)(REC->events)), ((unsigned long)(REC->timeout))
As you see, there are duplicated variable name among fields.
So I renamed the variable name 'nr' to 'syscall_nr' to avoid this
duplication. As you know 'nr' in print_syscall_enter() mean
system call number so, I changed 'nr' to 'syscall_nr'(IMHO).
Thanks,
Taeung
>>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Lai Jiangshan <jiangshanlai@...il.com>
>> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
>> ---
>> kernel/trace/trace.h | 4 ++--
>> kernel/trace/trace_syscalls.c | 16 ++++++++--------
>> 2 files changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
>> index 8414fa4..beddeb1 100644
>> --- a/kernel/trace/trace.h
>> +++ b/kernel/trace/trace.h
>> @@ -88,13 +88,13 @@ enum trace_type {
>> */
>> struct syscall_trace_enter {
>> struct trace_entry ent;
>> - int nr;
>> + int syscall_nr;
>> unsigned long args[];
>> };
>>
>> struct syscall_trace_exit {
>> struct trace_entry ent;
>> - int nr;
>> + int syscall_nr;
>> long ret;
>> };
>>
>> diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
>> index 0655afb..956209f 100644
>> --- a/kernel/trace/trace_syscalls.c
>> +++ b/kernel/trace/trace_syscalls.c
>> @@ -118,7 +118,7 @@ print_syscall_enter(struct trace_iterator *iter, int flags,
>> int i, syscall;
>>
>> trace = (typeof(trace))ent;
>> - syscall = trace->nr;
>> + syscall = trace->syscall_nr;
>> entry = syscall_nr_to_meta(syscall);
>>
>> if (!entry)
>> @@ -164,7 +164,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags,
>> struct syscall_metadata *entry;
>>
>> trace = (typeof(trace))ent;
>> - syscall = trace->nr;
>> + syscall = trace->syscall_nr;
>> entry = syscall_nr_to_meta(syscall);
>>
>> if (!entry) {
>> @@ -261,7 +261,7 @@ static int __init syscall_enter_define_fields(struct trace_event_call *call)
>> int i;
>> int offset = offsetof(typeof(trace), args);
>>
>> - ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
>> + ret = trace_define_field(call, SYSCALL_FIELD(int, syscall_nr), FILTER_OTHER);
>> if (ret)
>> return ret;
>>
>> @@ -281,7 +281,7 @@ static int __init syscall_exit_define_fields(struct trace_event_call *call)
>> struct syscall_trace_exit trace;
>> int ret;
>>
>> - ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
>> + ret = trace_define_field(call, SYSCALL_FIELD(int, syscall_nr), FILTER_OTHER);
>> if (ret)
>> return ret;
>>
>> @@ -332,7 +332,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
>> return;
>>
>> entry = ring_buffer_event_data(event);
>> - entry->nr = syscall_nr;
>> + entry->syscall_nr = syscall_nr;
>> syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
>>
>> event_trigger_unlock_commit(trace_file, buffer, event, entry,
>> @@ -378,7 +378,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
>> return;
>>
>> entry = ring_buffer_event_data(event);
>> - entry->nr = syscall_nr;
>> + entry->syscall_nr = syscall_nr;
>> entry->ret = syscall_get_return_value(current, regs);
>>
>> event_trigger_unlock_commit(trace_file, buffer, event, entry,
>> @@ -579,7 +579,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
>> if (!rec)
>> return;
>>
>> - rec->nr = syscall_nr;
>> + rec->syscall_nr = syscall_nr;
>> syscall_get_arguments(current, regs, 0, sys_data->nb_args,
>> (unsigned long *)&rec->args);
>> perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
>> @@ -652,7 +652,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
>> if (!rec)
>> return;
>>
>> - rec->nr = syscall_nr;
>> + rec->syscall_nr = syscall_nr;
>> rec->ret = syscall_get_return_value(current, regs);
>> perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
>> }
>
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