Re: [Virtio-fs] [PATCH 13/13] virtiofsd, seccomp: Add clock_nanosleep() to allow list

[Stefan Hajnoczi]

On Tue, Oct 05, 2021 at 01:28:21PM -0400, Vivek Goyal wrote:
> On Tue, Oct 05, 2021 at 04:50:43PM +0100, Stefan Hajnoczi wrote:
> > On Tue, Oct 05, 2021 at 11:16:18AM -0400, Vivek Goyal wrote:
> > > On Tue, Oct 05, 2021 at 01:22:58PM +0100, Stefan Hajnoczi wrote:
> > > > On Thu, Sep 30, 2021 at 11:30:37AM -0400, Vivek Goyal wrote:
> > > > > g_usleep() calls nanosleep() and that now seems to call 
> > > > > clock_nanosleep()
> > > > > syscall. Now these patches are making use of g_usleep(). So add
> > > > > clock_nanosleep() to list of allowed syscalls.
> > > > > 
> > > > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> > > > > ---
> > > > >  tools/virtiofsd/passthrough_seccomp.c | 1 +
> > > > >  1 file changed, 1 insertion(+)
> > > > > 
> > > > > diff --git a/tools/virtiofsd/passthrough_seccomp.c 
> > > > > b/tools/virtiofsd/passthrough_seccomp.c
> > > > > index cd24b40b78..03080806c0 100644
> > > > > --- a/tools/virtiofsd/passthrough_seccomp.c
> > > > > +++ b/tools/virtiofsd/passthrough_seccomp.c
> > > > > @@ -117,6 +117,7 @@ static const int syscall_allowlist[] = {
> > > > >      SCMP_SYS(writev),
> > > > >      SCMP_SYS(umask),
> > > > >      SCMP_SYS(nanosleep),
> > > > > +    SCMP_SYS(clock_nanosleep),
> > > > 
> > > > This patch can be dropped once sleep has been replaced by a condvar.
> > > 
> > > There is another sleep in do_pool_destroy() where we are waiting
> > > for all current threads to exit.
> > > 
> > > do_pool_destroy() {
> > >     g_usleep(10000);
> > > }
> > 
> > That won't be necessary if there's a way to avoid the thread pool :).
> > See my other reply about closing the OFD instead of using signals to
> > cancel blocking fcntl(2).
> 
> Hi Stefan,
> 
> I responded to that email already. man fnctl does not say anything
> about closing fd will unblock the waiter with -EINTR and I had a 
> quick look at kernel code and did not find anything which suggested
> closing fd will unblock current waiters.
> 
> So is this something you know works or you want me to try and see
> if it works?

Thanks for testing it!

Stefan

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