I'm sorry about many v1 patches posted. I fix some syntax errors in all v2 patches, and should note the changes in these patches. I will learn more about posting patch correctly. Thanks John. --- Best wishes, Wang Yechao 原始邮件 发件人：JohnFerlan <jferlan@redhat.com> 收件人：王业超10154425;libvir-list@redhat.com <libvir-list@redhat.com> 日 期 ：2018年09月14日 23:49 主 题 ：Re: [libvirt] [PATCH v2] nwfilter: fix deadlock when nwfilter reload 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@zte.com.cn> Reviewed-by: Wang Yi <wang.yi59@zte.com.cn> --- 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;