Date: Fri, 13 Oct 2017 23:38:49 +0200 From: Svatopluk Kraus <skra@freebsd.org> To: Mateusz Guzik <mjg@freebsd.org> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r324609 - head/sys/sys Message-ID: <CAFHCsPUzYewo1AaaKFE9LKVdUEw3Tr7c=Qpb=ah9XpwZ-OEEtg@mail.gmail.com> In-Reply-To: <201710132031.v9DKVueS089009@repo.freebsd.org> References: <201710132031.v9DKVueS089009@repo.freebsd.org>
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MTX_UNOWNED is a flag. You did not change its value from 4 to 0, you removed it actually. I have very bad feeling about it. But maybe, it's really possible and in that case, a very good explanation should be provided. Svata On Fri, Oct 13, 2017 at 10:31 PM, Mateusz Guzik <mjg@freebsd.org> wrote: > Author: mjg > Date: Fri Oct 13 20:31:56 2017 > New Revision: 324609 > URL: https://svnweb.freebsd.org/changeset/base/324609 > > Log: > mtx: change MTX_UNOWNED from 4 to 0 > > The value is spread all over the kernel and zeroing a register is > cheaper/shorter than setting it up to an arbitrary value. > > Reduces amd64 GENERIC-NODEBUG .text size by 0.4%. > > MFC after: 1 week > > Modified: > head/sys/sys/mutex.h > > Modified: head/sys/sys/mutex.h > ============================================================================== > --- head/sys/sys/mutex.h Fri Oct 13 20:29:35 2017 (r324608) > +++ head/sys/sys/mutex.h Fri Oct 13 20:31:56 2017 (r324609) > @@ -65,15 +65,11 @@ > * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this, > * with the exception of MTX_UNOWNED, applies to spin locks. > */ > +#define MTX_UNOWNED 0x00000000 /* Cookie for free mutex */ > #define MTX_RECURSED 0x00000001 /* lock recursed (for MTX_DEF only) */ > #define MTX_CONTESTED 0x00000002 /* lock contested (for MTX_DEF only) */ > -#define MTX_UNOWNED 0x00000004 /* Cookie for free mutex */ > -#define MTX_FLAGMASK (MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED) > - > -/* > - * Value stored in mutex->mtx_lock to denote a destroyed mutex. > - */ > -#define MTX_DESTROYED (MTX_CONTESTED | MTX_UNOWNED) > +#define MTX_DESTROYED 0x00000004 /* lock destroyed */ > +#define MTX_FLAGMASK (MTX_RECURSED | MTX_CONTESTED | MTX_DESTROYED) > > /* > * Prototypes >
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