Re: [RFC][PATCH 09/12 v3] seq_buf: Move the seq_buf code to lib/

Petr Mladek
2014-11-05T16:57:42Z

On Tue 2014-11-04 10:52:46, Steven Rostedt wrote:
> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
>
> The seq_buf functions are rather useful outside of tracing. Instead
> of having it be dependent on CONFIG_TRACING, move the code into lib/
> and allow other users to have access to it even when tracing is not
> configured.
>
> The seq_buf utility is similar to the seq_file utility, but instead of
> writing sending data back up to userland, it writes it into a buffer
> defined at seq_buf_init(). This allows us to send a descriptor around
> that writes printf() formatted strings into it that can be retrieved
> later.
>
> It is currently used by the tracing facility for such things like trace
> events to convert its binary saved data in the ring buffer into an
> ASCII human readable context to be displayed in /sys/kernel/debug/trace.
>
> It can also be used for doing NMI prints safely from NMI context into
> the seq_buf and retrieved later and dumped to printk() safely. Doing
> printk() from an NMI context is dangerous because an NMI can preempt
> a current printk() and deadlock on it.
>
> Link: http://lkml.kernel.org/p/20140619213952.058255809@goodmis.org
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

This patch might needed an update when there are changes in the
previous patches. But it is a simple file move that makes
perfect sense, so:

Reviewed-by: Petr Mladek <pmladek@suse.cz>

Best Regards,
Petr