linux-kernel - Re: [PATCH RESEND 1/3] tracing/syscalls: Rename variable 'nr' to 'syscall

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Message-ID: <20160225104741.2cd3bf14@gandalf.local.home>
Date:	Thu, 25 Feb 2016 10:47:41 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Taeung Song <treeze.taeung@...il.com>
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'

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?

-- Steve

> 
> 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);
>  }