Date: Wed, 24 Sep 2014 10:58:11 -0400 From: John Baldwin <jhb@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Bryan Drewery <bdrewery@freebsd.org> Subject: Re: svn commit: r272032 - head/sys/conf Message-ID: <18894593.erVri7Abnd@ralph.baldwin.cx> In-Reply-To: <20140924142339.GJ8870@kib.kiev.ua> References: <201409231704.s8NH4Lcv098184@svn.freebsd.org> <8280436.uSRo73F0Mt@ralph.baldwin.cx> <20140924142339.GJ8870@kib.kiev.ua>
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On Wednesday, September 24, 2014 05:23:39 PM Konstantin Belousov wrote: > On Wed, Sep 24, 2014 at 09:58:07AM -0400, John Baldwin wrote: > > On Tuesday, September 23, 2014 09:44:34 PM Konstantin Belousov wrote: > > > On Tue, Sep 23, 2014 at 01:31:42PM -0500, Bryan Drewery wrote: > > > > On 9/23/2014 1:20 PM, Konstantin Belousov wrote: > > > > > On Tue, Sep 23, 2014 at 05:04:21PM +0000, Bryan Drewery wrote: > > > > >> Author: bdrewery > > > > >> Date: Tue Sep 23 17:04:21 2014 > > > > >> New Revision: 272032 > > > > >> URL: http://svnweb.freebsd.org/changeset/base/272032 > > > > >> > > > > >> Log: > > > > >> DEBUG_LOCKS no longer modifies 'struct vnode', nor does fstat(1) > > > > >> use > > > > >> it. > > > > >> fstat(1) now uses libprocstat(9). There is no userland impact to > > > > >> using this.> > > > > > > > > > > > DEBUG_VFS_LOCKS does modify KBI of VFS, by adding struct stack to > > > > > lockmgr, and lockmgr is embedded into each struct vnode. > > > > > > > > > > VFS modules, in particular, filesystems, compiled for mismatched > > > > > kernel WRT DEBUG_VFS_LOCKS, would cause strange breakage. > > > > > > > > Well, perhaps the comment needs to be updated to state that > > > > DEBUG_VFS_LOCKS modifies VFS KBI so any VFS modules will need to > > > > recompiled. > > > > > > > > I did see the stack was moved to lockmgr, but given the use of > > > > libprocstat, and lockmgr being a kernel struct, I don't think it's > > > > worth > > > > mentioning userland here. > > > > > > > > Sound good? > > > > > > I agree, I do not think that userland is affected. > > > > It is for at least lsof (which does not use libprocstat and cannot easily > > be adopted to use it exclusively as it pulls a lot more data out than > > libprocstat exports such as the info about file locks, etc.) > > We cannot seriously consider the lsof as application which uses > stable interfaces. I.e., binary incompatibility for lsof even > on the stable branch or on -pX is not an issue. > > Lsof verifies kernel release name and warns if it differs from the > one used at the compilation time, rightfully. I don't disagree. Just noting that it is a commonly-used tool that is affected by DEBUG_LOCKS. -- John Baldwin
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