Re: [PULL v2 00/51] Block layer patches

[Kevin Wolf]

Am 15.12.2022 um 15:44 hat Peter Maydell geschrieben:
> On Thu, 15 Dec 2022 at 11:59, Kevin Wolf <kwolf@redhat.com> wrote:
> >
> > The following changes since commit 5204b499a6cae4dfd9fe762d5e6e82224892383b:
> >
> >   mailmap: Fix Stefan Weil author email (2022-12-13 15:56:57 -0500)
> >
> > are available in the Git repository at:
> >
> >   https://repo.or.cz/qemu/kevin.git tags/for-upstream
> >
> > for you to fetch changes up to 347fe9e156a3e00c40ae1802978276a1f7d5545f:
> >
> >   block: GRAPH_RDLOCK for functions only called by co_wrappers (2022-12-15 
> > 10:11:45 +0100)
> >
> > v2:
> > - Changed TSA capability name to "mutex" to work with older clang
> >   versions. The tsan-build CI job succeeds now.
> >
> > ----------------------------------------------------------------
> > Block layer patches
> >
> > - Code cleanups around block graph modification
> > - Simplify drain
> > - coroutine_fn correctness fixes, including splitting generated
> >   coroutine wrappers into co_wrapper (to be called only from
> >   non-coroutine context) and co_wrapper_mixed (both coroutine and
> >   non-coroutine context)
> > - Introduce a block graph rwlock
> 
> This fails to compile on the FreeBSD 12 and 13 jobs:
> https://gitlab.com/qemu-project/qemu/-/jobs/3479763741
> https://gitlab.com/qemu-project/qemu/-/jobs/3479763746
> 
> The compiler is producing -Wthread-safety-analysis
> warnings on code in qemu-thread-posix.c, which are a
> compile failure because of -Werror.

Hmm... FreeBSD actually annotates it pthread locking functions for TSA,
so all callers need to be annotated as well. I guess it's nice in
theory, but hard to enable for a huge codebase like QEMU...

I'll just drop "configure: Enable -Wthread-safety if present" for now.

Maybe we can have a configure check later to enable it by default on
glibc at least. Or we really need to go through all locks in QEMU and
annotate them properly. This might be a bit too painful, though, so we
may end up leaving FreeBSD unchecked even if that seems to be the OS to
care most about it...

Kevin