From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754331AbcBZN5U (ORCPT ); Fri, 26 Feb 2016 08:57:20 -0500 Received: from mail.kernel.org ([198.145.29.136]:38821 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751021AbcBZN5T (ORCPT ); Fri, 26 Feb 2016 08:57:19 -0500 Date: Fri, 26 Feb 2016 10:57:13 -0300 From: Arnaldo Carvalho de Melo To: Steven Rostedt , Peter Zijlstra , Ingo Molnar Cc: Taeung Song , linux-kernel@vger.kernel.org, Jiri Olsa , Namhyung Kim , Thomas Gleixner , Lai Jiangshan Subject: [RFC] Re: [PATCH v3 1/2] tracing/syscalls: Rename variable 'nr' to '__syscall_nr' Message-ID: <20160226135713.GU8720@kernel.org> References: <1456492446-5896-1-git-send-email-treeze.taeung@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1456492446-5896-1-git-send-email-treeze.taeung@gmail.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Fri, Feb 26, 2016 at 10:14:06PM +0900, Taeung Song escreveu: > There is a problem about duplicated variable name i.e. > > # cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_io_getevents/format > name: sys_enter_io_getevents > ID: 739 > format: Steven, what do you think? Should we break this ABI while disambiguating the 'nr' field, using '__syscall_nr' in an attempt to use a name that is unlikely to be used by a real syscall argument name? If we stand by published ABIs, we should keep it written in stone and state that the first 'nr' means '__syscall_nr' while keeping it as-is, the change for 'perf trace' in that case is to do nothing, it work as-is, we have just to fix the python binding to do that rename. Perhaps we can live with that, to avoid having three different cases: !nr, nr and __syscall_nr. Ingo, Peter, have you guys followed this case? Summary: Some tracepoint have multiple fields with the same name, 'nr', the first one is a unique syscall ID, the other is a syscall argument: [root@jouet ~]# cat /sys/kernel/debug/tracing/events/syscalls/sys_enter_io_getevents/format name: sys_enter_io_getevents ID: 747 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)) [root@jouet ~]# - Arnaldo > 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 above 'int nr;' and 'long nr;' variables have > duplicated name so problems are occurred in perf-script i.e. > > # 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. > Not only sys_enter_io_getevent() but also sys_enter_io_submit() > have relevevance to this problem. > > So rename a variable 'nr' to '__syscall_nr' for system call number > in print_syscall_enter() and etc. > > Cc: Thomas Gleixner > Cc: Lai Jiangshan > Signed-off-by: Taeung Song > --- > 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..98b3c66 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..90bb468 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); > } > -- > 2.5.0