config/output: don't change output state before commit

Previously, we called output_disable prior to wlr_output_commit. This
mutates Sway's output state before the output commit actually succeeds.
This results in Sway's state getting out-of-sync with wlroots'.

An alternative fix [1] was to revert the changes made by output_disable
in case of failure. This is a little complicated. Instead, this patch
makes it so Sway's internal state is never changed before a successful
wlr_output commit.

We had two output flags: enabled and configured. However enabled was set
prior to the output becoming enabled, and was used to prevent the output
event handlers (specifically, the mode handler) from calling
apply_output_config again (infinite loop).

Rename enabled to enabling and use it exclusively for this purpose.
Rename configure to enabled, because that's what it really means.

[1]: https://github.com/swaywm/sway/pull/5521

Closes: https://github.com/swaywm/sway/issues/5483
(cherry picked from commit 5432f00adfdd8375fb422ad9033253d17f04efc7)

1 files changed, 12 insertions, 14 deletions

diff --git a/sway/config/output.c b/sway/config/output.c
index 68aafbe1..b59cabd4 100644
--- a/sway/config/output.c
+++ b/sway/config/output.c
@@ -397,17 +397,8 @@ bool apply_output_config(struct output_config *oc, struct sway_output *output) {
 
         struct wlr_output *wlr_output = output->wlr_output;
 
-        bool was_enabled = output->enabled;
-        if (oc && !oc->enabled) {
-                // Output is configured to be disabled
-                sway_log(SWAY_DEBUG, "Disabling output %s", oc->name);
-                if (output->enabled) {
-                        output_disable(output);
-                        wlr_output_layout_remove(root->output_layout, wlr_output);
-                }
-        } else {
-                output->enabled = true;
-        }
+        // Flag to prevent the output mode event handler from calling us
+        output->enabling = (!oc || oc->enabled);
 
         queue_output_config(oc, output);
 
@@ -421,11 +412,18 @@ bool apply_output_config(struct output_config *oc, struct sway_output *output) {
                 // Leave the output disabled for now and try again when the output gets
                 // the mode we asked for.
                 sway_log(SWAY_ERROR, "Failed to commit output %s", wlr_output->name);
-                output->enabled = was_enabled;
+                output->enabling = false;
                 return false;
         }
 
+        output->enabling = false;
+
         if (oc && !oc->enabled) {
+                sway_log(SWAY_DEBUG, "Disabling output %s", oc->name);
+                if (output->enabled) {
+                        output_disable(output);
+                        wlr_output_layout_remove(root->output_layout, wlr_output);
+                }
                 return true;
         }
 
@@ -468,8 +466,8 @@ bool apply_output_config(struct output_config *oc, struct sway_output *output) {
         output->width = output_box->width;
         output->height = output_box->height;
 
-        if (!output->configured) {
-                output_configure(output);
+        if (!output->enabled) {
+                output_enable(output);
         }
 
         if (oc && oc->max_render_time >= 0) {