where's the definition of trace_kfree_skb?

where's the definition of trace_kfree_skb?

[Shiyao Ma]

Hi,
I saw this function invocation,
trace_kfree_skb(skb, __builtin_return_address(0));

so I grepped the source for "trace_kfree_skb", but I found no where it's defined.

Where's the definition for it?


Best,
Shiyao.



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where's the definition of trace_kfree_skb?

[valdis.kletnieks at vt.edu]

On Tue, 28 Mar 2017 16:15:57 +0800, Shiyao Ma said:

> I saw this function invocation,
> trace_kfree_skb(skb, __builtin_return_address(0));
>
> so I grepped the source for "trace_kfree_skb", but I found no where it's defined.

For some uses, the Linux kernel forms a definition via the preprocessor, by
gluing together several strings.

Try doing 'git grep trace_##'  (or 'grep -r trace_## .' if you don't have a git tree.
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where's the definition of trace_kfree_skb?

[Rawcoder]

Hello,

On Tuesday 28 March 2017 01:45 PM, Shiyao Ma wrote:
> Hi,
> I saw this function invocation, 
> trace_kfree_skb(skb, __builtin_return_address(0));
> 
> so I grepped the source for "trace_kfree_skb", but I found no where it's defined.
> 
> Where's the definition for it?
> 

It is a tracepoint call.

Tracepoints are defined using DECLARE_TRACE or TRACE_EVENT macros [1].

'git grep "TRACE.*kfree_skb"' gives the desired definition.



[1]: https://www.kernel.org/doc/Documentation/trace/tracepoints.txt


Regards,
rawcoder

where's the definition of trace_kfree_skb?

[Nicholas Mc Guire]

On Tue, Mar 28, 2017 at 04:15:57PM +0800, Shiyao Ma wrote:
> Hi,
> I saw this function invocation,
> trace_kfree_skb(skb, __builtin_return_address(0));
> 
> so I grepped the source for "trace_kfree_skb", but I found no where it's defined.
> 
> Where's the definition for it?
>
that is a generated functions so you do not find them in the kernel
sources directly - but you can find the generation points in the
case of trace_kfree_skb thats in
  include/trace/events/skb.h:TRACE_EVENT(kfree_skb,... -> DECLARE_TRACE(...)
and then exported in
  net/core/net-traces.c:EXPORT_TRACEPOINT_SYMBOL_GPL(kfree_skb);
the detailed description of TRACE_EVENT can be found in
  include/linux/tracepoint.h

thx!
hofrat

where's the definition of trace_kfree_skb?

[Shiyao Ma]

Thanks you guys!

Best,
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