Re: [PATCH] tracing: Export key trace event symbols

From: Christoph Hellwig
Date: Tue Apr 21 2015 - 02:10:43 EST


On Mon, Apr 20, 2015 at 04:38:11PM -0500, Ron Rechenmacher wrote:
> If symbols are not exported, modules can no longer register additional
> (module specified) tracepoints like they use to be able to (i.e linux-3.15.x).
> Somewhere on or about commit de7b2973903c6cc50b31ee5682a69b2219b9919d
> (Author: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Date: Tue Apr 8 17:26:21 2014 -0400
> tracepoint: Use struct pointer instead of name hash for reg/unreg tracepoints)
> modules which attempted to register additional tracing functions would
> get "Unknown symbol" errors. For example: "... Unknown symbol
> __tracepoint_sched_switch (err 0)"
> Symbols can be exported using the kernel's EXPORT_TRACEPOINT_SYMBOL_GPL macro
> to allow modules to once again register their own tracing functions (for at
> least some key points in the kernel as provided by this patch).

Which (in-tree) module fails with this? I don't think anyone should
actually register a symbol.

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