[libvirt PATCH 2/2] util: avoid glib event loop workaround where possible

I previously did a workaround for a glib event loop race that causes crashes: commit 0db4743645b7a0611a3c0687f834205c9956f7fc Author: Daniel P. Berrangé <berrange(a)redhat.com&gt; Date: Tue Jul 28 16:52:47 2020 +0100 util: avoid crash due to race in glib event loop code it turns out that the workaround has a significant performance penalty on I/O intensive workloads. We thus need to avoid the workaround if we know we have a new enough glib to avoid the race condition. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- src/util/vireventglib.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) diff --git a/src/util/vireventglib.c b/src/util/vireventglib.c index 6842c6e806..8c5495bfab 100644 --- a/src/util/vireventglib.c +++ b/src/util/vireventglib.c @@ -189,9 +189,21 @@ virEventGLibHandleFind(int watch) * If the last reference to a GSource is released in a non-main * thread we're exposed to a race condition that causes a * crash: - * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1358 - * Thus we're using an idle func to release our ref + * + * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1358 + * + * Thus we're using an idle func to release our ref... + * + * ...but this imposes a significant performance penalty on + * I/O intensive workloads which are sensitive to the iterations + * of the event loop, so avoid the workaround if we know we have + * new enough glib. */ +#if GLIB_CHECK_VERSION(2, 64, 0) +# define g_vir_source_unref_safe(source) g_source_unref(source) +#else +# define g_vir_source_unref_safe(source) g_idle_add(virEventGLibSourceUnrefIdle, source); + static gboolean virEventGLibSourceUnrefIdle(gpointer data) { @@ -201,6 +213,7 @@ virEventGLibSourceUnrefIdle(gpointer data) return FALSE; } +#endif static void @@ -231,7 +244,7 @@ virEventGLibHandleUpdate(int watch, if (data->source != NULL) { VIR_DEBUG("Removed old handle source=%p", data->source); g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); } data->source = virEventGLibAddSocketWatch( @@ -245,7 +258,7 @@ virEventGLibHandleUpdate(int watch, VIR_DEBUG("Removed old handle source=%p", data->source); g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); data->source = NULL; data->events = 0; } @@ -294,7 +307,7 @@ virEventGLibHandleRemove(int watch) if (data->source != NULL) { g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); data->source = NULL; data->events = 0; } @@ -427,7 +440,7 @@ virEventGLibTimeoutUpdate(int timer, if (interval >= 0) { if (data->source != NULL) { g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); } data->interval = interval; @@ -437,7 +450,7 @@ virEventGLibTimeoutUpdate(int timer, goto cleanup; g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); data->source = NULL; } @@ -486,7 +499,7 @@ virEventGLibTimeoutRemove(int timer) if (data->source != NULL) { g_source_destroy(data->source); - g_idle_add(virEventGLibSourceUnrefIdle, data->source); + g_vir_source_unref_safe(data->source); data->source = NULL; } -- 2.25.4