Re: [PATCH 1/4] tracing/uprobes: Revert "Support mix of ftrace and perf"

[Srikar Dronamraju]

* Oleg Nesterov <oleg@xxxxxxxxxx> [2014-06-27 19:01:36]:

> This reverts commit 43fe98913c9f67e3b523615ee3316f9520a623e0.
> 
> This patch is very wrong. Firstly, this change leads to unbalanced
> uprobe_unregister(). Just for example,
> 
> 	# perf probe -x /lib/libc.so.6 syscall
> 	# echo 1 >> /sys/kernel/debug/tracing/events/probe_libc/enable
> 	# perf record -e probe_libc:syscall whatever
> 
> after that uprobe is dead (unregistered) but the user of ftrace/perf
> can't know this, and it looks as if nobody hits this probe.
> 
> This would be easy to fix, but there are other reasons why it is not
> simple to mix ftrace and perf. If nothing else, they can't share the
> same ->consumer.filter. This is fixable too, but probably we need to
> fix the poorly designed uprobe_register() interface first. At least
> "register" and "apply" should be clearly separated.
> 
> Cc: stable@xxxxxxxxxxxxxxx # v3.14
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>

Acked-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

-- 
Thanks and Regards
Srikar Dronamraju

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