svn commit: r313878 - head/sys/kern

[Mateusz Guzik]

On Mon, Feb 20, 2017 at 04:24:50PM -0800, Bryan Drewery wrote:
> On 2/17/2017 7:40 AM, Mateusz Guzik wrote:
> > Author: mjg
> > Date: Fri Feb 17 15:40:24 2017
> > New Revision: 313878
> > URL: https://svnweb.freebsd.org/changeset/base/313878
> > 
> > Log:
> >   mtx: get rid of file/line args from slow paths if they are unused
> >   
> >   This denotes changes which went in by accident in r313877.
> 
> I really wish people would just revert their changes and recommit them
> properly.  The 'svn blame' on the code in r313877 will never show the
> commit message here (r313878).  So a person would only find this
> explanation if they read 'svn log' on the file, which in the case of
> sys/kern/kern_mutex.c there are 273 commits for.  Are we expected to
> read 'svn log' (in the future) for all changes in the hopes that a later
> commit happens to mention it?
> 
> As someone who so often is 'svn blame'ing code to understand it better
> and to track regressions, commits like this that explain other commits
> might as well have never been done.
> 

In general I agree, but also don't think the change was worth any
additional churn. It only removed 2 args when not under LOCK_DEBUG. The
commit message above is only to note KBI is covered as this could be of
concern for a casual reader.

I would not do this if the change was doing anything non-trivial.

> >   
> >   On most production kernels both said parameters are zeroed and have nothing
> >   reading them in either __mtx_lock_sleep or __mtx_unlock_sleep. Thus this change
> >   stops passing them by internal consumers which this is the case.
> >   
> >   Kernel modules use _flags variants which are not affected kbi-wise.
> > 
> > Modified:
> >   head/sys/kern/kern_mutex.c
> > 
> > Modified: head/sys/kern/kern_mutex.c
> > ==============================================================================
> > --- head/sys/kern/kern_mutex.c	Fri Feb 17 15:34:40 2017	(r313877)
> > +++ head/sys/kern/kern_mutex.c	Fri Feb 17 15:40:24 2017	(r313878)
> > @@ -622,7 +622,7 @@ __mtx_lock_sleep(volatile uintptr_t *c, 
> >  		LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
> >  
> >  	/*
> > -	 * Only record the loops spinning and not sleeping. 
> > +	 * Only record the loops spinning and not sleeping.
> >  	 */
> >  	if (lda.spin_cnt > sleep_cnt)
> >  		LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
> > 
> 
> 
> -- 
> Regards,
> Bryan Drewery
> 




-- 
Mateusz Guzik <mjguzik gmail.com>