On Tue, Sep 19, 2017 at 02:59:37PM -0500, Eric Blake wrote: > On 09/14/2017 02:50 AM, Peter Xu wrote: > > This is not a problem if we are only having one single loop thread like > > before. However, after per-monitor thread is introduced, this is not > > true any more, and the race can happen. > > > > The race can be triggered with "make check -j8" sometimes: > > > > qemu-system-x86_64: /root/git/qemu/chardev/char-io.c:91: > > io_watch_poll_finalize: Assertion `iwp->src == NULL' failed. > > > > This patch keeps the reference for the watch object when creating in > > io_add_watch_poll(), so that the object will never be released in the > > context main loop, especially when the context loop is running in > > another standalone thread. Meanwhile, when we want to remove the watch > > object, we always first detach the watch object from its owner context, > > then we continue with the cleanup. > > > > Without this patch, calling io_remove_watch_poll() in main loop thread > > is not thread-safe, since the other per-monitor thread may be modifying > > the watch object at the same time. > > > > Reviewed-by: Marc-André Lureau <marcandre.lur...@redhat.com> > > Signed-off-by: Peter Xu <pet...@redhat.com> > > --- > > > + * Let's blame the glib bug mentioned in commit 2b3167 (again) for > > That 6-char commit id may become ambiguous soon (it's still rare to see > ambiguity with an 8-char id, although I've seen it more in recent times > than in the past; and git itself has moved from a 7-char default > abbreviation length in the 2.0 days to what is now a 10-char default > abbreviation in 2.13.5).
Thanks for noticing this. I'll use 10 chars in next post. -- Peter Xu
