On 09/29/2014 04:04 PM, Steven Rostedt wrote:
> On Mon, 29 Sep 2014 13:58:55 +0200
> Hannes Reinecke <h...@suse.de> wrote:
> 
>> From: "Steven Rostedt (Red Hat)" <rost...@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/20140619213952.058255...@goodmis.org
> 
> I don't know where this is going, but I'm currently rewriting this
> code. Please don't add it yet to the kernel yet. I'm working on getting
> seq_buf and seq_file to be more inlined with each other. A much better
> sell if we can remove code with this change.
> 
Hmm. I guess I'll be removing the respective patches then.
I can get quite the same results with using scnprintf(); the seq_buf
abstraction was just a nice way of coding.
No substantial difference here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                   zSeries & Storage
h...@suse.de                          +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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