Re: [PATCH V2 2/7] mm/gup: add gup trace points

From	Steven Rostedt <rostedt@goodmis.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH V2 2/7] mm/gup: add gup trace points
Date	2015-12-03 20:10 +0100
Message-ID	<qBHqp-Kh-7@gated-at.bofh.it> (permalink)
References	<qBoQN-5n9-1@gated-at.bofh.it> <qBoQP-5n9-51@gated-at.bofh.it> <qBpaa-5uf-19@gated-at.bofh.it> <qBtx7-8sd-5@gated-at.bofh.it> <qBGXo-j5-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Thu, 03 Dec 2015 10:36:18 -0800
"Shi, Yang" <yang.shi@linaro.org> wrote:

> > called directly that calls these functions internally and the tracepoint
> > can trap the return value.  
> 
> This will incur more changes in other subsystems (futex, kvm, etc), I'm 
> not sure if it is worth making such changes to get return value.

No, it wouldn't require any changes outside of this.

-long __get_user_pages(..)
+static long __get_user_pages_internal(..)
{
  [..]
}
+
+long __get_user_pages(..)
+{
+	long ret;
+	ret = __get_user_pages_internal(..);
+	trace_get_user_pages(.., ret)
+}

> 
> > I can probably make function_graph tracer give return values, although
> > it will give a return value for void functions as well. And it may give
> > long long returns for int returns that may have bogus data in the
> > higher bits.  
> 
> If the return value requirement is not limited to gup, the approach 
> sounds more reasonable.
>

Others have asked about it. Maybe I should do it.

-- Steve

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Thread

[RFC V2] Add gup trace points support Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
  [PATCH V2 5/7] s390: mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
  [PATCH V2 3/7] x86: mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
  [PATCH V2 4/7] mips: mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
  [PATCH V2 2/7] mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
    Re: [PATCH V2 2/7] mm/gup: add gup trace points Dave Hansen <dave.hansen@intel.com> - 2015-12-03 00:40 +0100
      Re: [PATCH V2 2/7] mm/gup: add gup trace points "Shi, Yang" <yang.shi@linaro.org> - 2015-12-03 01:20 +0100
        Re: [PATCH V2 2/7] mm/gup: add gup trace points "Shi, Yang" <yang.shi@linaro.org> - 2015-12-03 02:00 +0100
      Re: [PATCH V2 2/7] mm/gup: add gup trace points Steven Rostedt <rostedt@goodmis.org> - 2015-12-03 05:20 +0100
        Re: [PATCH V2 2/7] mm/gup: add gup trace points "Shi, Yang" <yang.shi@linaro.org> - 2015-12-03 19:40 +0100
          Re: [PATCH V2 2/7] mm/gup: add gup trace points Steven Rostedt <rostedt@goodmis.org> - 2015-12-03 20:10 +0100
            Re: [PATCH V2 2/7] mm/gup: add gup trace points "Shi, Yang" <yang.shi@linaro.org> - 2015-12-03 23:20 +0100
  [PATCH V2 6/7] sh: mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
  [PATCH V2 1/7] trace/events: Add gup trace events Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:20 +0100
    Re: [PATCH V2 1/7] trace/events: Add gup trace events Steven Rostedt <rostedt@goodmis.org> - 2015-12-03 05:10 +0100
      Re: [PATCH V2 1/7] trace/events: Add gup trace events "Shi, Yang" <yang.shi@linaro.org> - 2015-12-03 19:40 +0100
  [PATCH V2 7/7] sparc64: mm/gup: add gup trace points Yang Shi <yang.shi@linaro.org> - 2015-12-03 00:30 +0100

csiph-web