On 09/13/2018 07:15 AM, Wang Yechao wrote: > user run "firewalld-cmd --reload" > nwfilterStateReload called in main thread > step 1. virRWLockWrite(&updateLock) > step 2. virNWFilterLoadAllConfigs > step 3. virRWLockUnlock(&updateLock); > > lauch a vm: qemuDomainCreateXML runs in other thread > step 1. virRWLockRead(&updateLock); > step 2. qemuProcessStart > step 3. qemuProcessWaitForMonitor > step 4. ... > step 5 virRWLockUnlock(&updateLock); > > if nwfilterStateReload called in the middle of step 1 and step 5 of > qemuDomainCreateXML, it can't get the updateLock and then block the event_loop, > so event_loop can't handle the qemu-monitor messages, cause deadlock > > move nwfilterStateReload into thread to fix this problem. > > Signed-off-by: Wang Yechao <wang.yechao255@xxxxxxxxxx> > Reviewed-by: Wang Yi <wang.yi59@xxxxxxxxxx> > --- > src/nwfilter/nwfilter_driver.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > Couple of "administrative" comments - since you were a new contributor to libvir-list - you just needed to be a bit more patient w/r/t getting your patches on this list, as described here: https://libvirt.org/hacking.html "If everything went well, your patch should show up on the libvir-list archives in a matter of minutes; if you still can't find it on there after an hour or so, you should double-check your setup. Note that your very first post to the mailing list will be subject to moderation, and it's not uncommon for that to take around a day. " OK so that hopefully helps explain why there were many v1's posted Then when you repost a few days later with something that's changed, you need to change to using v2. In the postings on Sept 11 it seems you've change the R-By email address. That's important enough to note... Then when you posted as v2, it probably should have been v3 and a note added why you changed from VIR_ERROR to VIR_WARN For each of these addition versions after the "---" (above): 1. Add a pointer to the previous posting from the archives 2. Briefly describe the differences in the changes So, after all that... This seemed really familiar... and it was: See: https://www.redhat.com/archives/libvir-list/2017-October/msg01351.html and follow-ups: https://www.redhat.com/archives/libvir-list/2017-December/msg00198.html https://www.redhat.com/archives/libvir-list/2017-December/msg00227.html However, that followup was essentially dropped. So this code once again resurrects the same questions that I had back then. Not that I don't think this should be done in some form, the question becomes how much "care" needs to be taken to ensure we don't have multiple threads running. John BTW: Whether you were aware of Nikolay's patch or not, I think some attribution could be made even though it was the same solution. > diff --git a/src/nwfilter/nwfilter_driver.c b/src/nwfilter/nwfilter_driver.c > index 1ee5162..ab85072 100644 > --- a/src/nwfilter/nwfilter_driver.c > +++ b/src/nwfilter/nwfilter_driver.c > @@ -80,18 +80,26 @@ static void nwfilterDriverUnlock(void) > } > > #if HAVE_FIREWALLD > +static void nwfilterReloadThread(void *opaque ATTRIBUTE_UNUSED) > +{ > + nwfilterStateReload(); > +} > > static DBusHandlerResult > nwfilterFirewalldDBusFilter(DBusConnection *connection ATTRIBUTE_UNUSED, > DBusMessage *message, > void *user_data ATTRIBUTE_UNUSED) > { > + virThread thread; > + > if (dbus_message_is_signal(message, DBUS_INTERFACE_DBUS, > "NameOwnerChanged") || > dbus_message_is_signal(message, "org.fedoraproject.FirewallD1", > "Reloaded")) { > VIR_DEBUG("Reload in nwfilter_driver because of firewalld."); > - nwfilterStateReload(); > + > + if (virThreadCreate(&thread, false, nwfilterReloadThread, NULL) < 0) > + VIR_WARN("create nwfilterReloadThread failed."); > } > > return DBUS_HANDLER_RESULT_NOT_YET_HANDLED; > -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
