svn commit: r346120 - head/sys/kern

[Konstantin Belousov]

On Fri, Apr 12, 2019 at 03:28:26PM +0100, Edward Napierala wrote:
> On Thu, 11 Apr 2019 at 17:26, Conrad Meyer <cem at freebsd.org> wrote:
> >
> > Hi Edward,
> >
> > I have a question about this change below.
> >
> > On Thu, Apr 11, 2019 at 4:22 AM Edward Tomasz Napierala
> > <trasz at freebsd.org> wrote:
> > >
> > > Author: trasz
> > > Date: Thu Apr 11 11:21:45 2019
> > > New Revision: 346120
> > > URL: https://svnweb.freebsd.org/changeset/base/346120
> > >
> > > Log:
> > >   Use shared vnode locks for the ELF interpreter.
> 
> [..]
> 
> > On the one hand, perhaps VOP_IS_TEXT() is rarely false for common
> > interpreters anyway.  On the other hand, there is sort of a
> > renaissance of static linking happening.  So maybe the thought is,
> > !VOP_IS_TEXT is likely to be rare, and LK_UPGRADE success even more
> > rare, so why bother writing additional code for it?
> 
> Konstantin already answered to most of the points, but regarding
> this one: that's exactly the case.  In a typical case, the number of times
> this code path will be executed is zero.  I'd expect one - when running
> dynamically linked ELF binary for the first time - but for some reason in
> that case lookup() returns with the exclusive vnode lock already held.

This is strange.  Which filesystem do you use ?