This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [PATCH tracing/kprobes v2 2/5] tracing/kprobes: Avoid field name confliction
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: rostedt at goodmis dot org
- Cc: Frederic Weisbecker <fweisbec at gmail dot com>, Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>, Thomas Gleixner <tglx at linutronix dot de>, Arnaldo Carvalho de Melo <acme at redhat dot com>, Mike Galbraith <efault at gmx dot de>, Paul Mackerras <paulus at samba dot org>, Peter Zijlstra <a dot p dot zijlstra at chello dot nl>, Christoph Hellwig <hch at infradead dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, "Frank Ch. Eigler" <fche at redhat dot com>
- Date: Mon, 05 Oct 2009 21:07:20 -0400
- Subject: Re: [PATCH tracing/kprobes v2 2/5] tracing/kprobes: Avoid field name confliction
- References: <20091002214834.30906.86502.stgit@dhcp-100-2-132.bos.redhat.com> <20091002214850.30906.25919.stgit@dhcp-100-2-132.bos.redhat.com> <1254788218.13160.198.camel@gandalf.stny.rr.com>
Steven Rostedt wrote:
> On Fri, 2009-10-02 at 17:48 -0400, Masami Hiramatsu wrote:
>> Check whether the argument name is conflict with other field names.
>>
>> Changes in v2:
>> - Add common_lock_depth to reserved name list.
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Ingo Molnar <mingo@elte.hu>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Mike Galbraith <efault@gmx.de>
>> Cc: Paul Mackerras <paulus@samba.org>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Christoph Hellwig <hch@infradead.org>
>> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>> Cc: Jim Keniston <jkenisto@us.ibm.com>
>> Cc: Frank Ch. Eigler <fche@redhat.com>
>> ---
>>
>> kernel/trace/trace_kprobe.c | 65 +++++++++++++++++++++++++++++++++++--------
>> 1 files changed, 53 insertions(+), 12 deletions(-)
>>
>> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
>> index f63ead0..eb1fa0f 100644
>> --- a/kernel/trace/trace_kprobe.c
>> +++ b/kernel/trace/trace_kprobe.c
>> @@ -38,6 +38,25 @@
>> #define MAX_EVENT_NAME_LEN 64
>> #define KPROBE_EVENT_SYSTEM "kprobes"
>>
>> +/* Reserved field names */
>> +#define FIELD_STRING_IP "ip"
>> +#define FIELD_STRING_NARGS "nargs"
>> +#define FIELD_STRING_RETIP "ret_ip"
>> +#define FIELD_STRING_FUNC "func"
>> +
>> +const char *reserved_field_names[] = {
>> + "common_type",
>> + "common_flags",
>> + "common_preempt_count",
>> + "common_pid",
>> + "common_tgid",
>> + "common_lock_depth",
>> + FIELD_STRING_IP,
>> + FIELD_STRING_NARGS,
>> + FIELD_STRING_RETIP,
>> + FIELD_STRING_FUNC,
>> +};
>> +
>> /* currently, trace_kprobe only supports X86. */
>>
>> struct fetch_func {
>> @@ -551,6 +570,20 @@ static int parse_probe_arg(char *arg, struct fetch_func *ff, int is_return)
>> return ret;
>> }
>>
>> +/* Return 1 if name is reserved or already used by another argument */
>> +static int conflict_field_name(const char *name,
>> + struct probe_arg *args, int narg)
>> +{
>> + int i;
>> + for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
>> + if (!strcmp(reserved_field_names[i], name))
>> + return 1;
>> + for (i = 0; i < narg; i++)
>> + if (!strcmp(args[i].name, name))
>> + return 1;
>
> Just a coding preference, but still, I've seen too many mistakes (made
> them myself too).
>
> if (strcmp(args[i].name, name) == 0)
>
> Looks better as a match then
>
> if (!strcmp(args[i].name, name))
>
> That stands out to me as a miss match. But this is still just a
> preference and not something to make me argue the patch.
Agreed, !strcmp() pattern would better be warned by checkpatch.pl :-)
I'll fix that.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com