From 943cbe37079d3e102cc5a0e7fecfe868d505d262 Mon Sep 17 00:00:00 2001
From: bjorn3 <17426603+bjorn3@users.noreply.github.com>
Date: Sat, 15 Mar 2025 16:27:04 +0100
Subject: [PATCH] graphics/fbbootlogd: Remove workaround that prevents blocking
 on the graphics driver

Instead logd will no longer block on fbbootlogd to prevent the deadlock
that this worked around.
---
 graphics/fbbootlogd/src/display.rs | 37 ++++--------------------------
 graphics/fbbootlogd/src/main.rs    | 10 ++++----
 2 files changed, 8 insertions(+), 39 deletions(-)

diff --git a/graphics/fbbootlogd/src/display.rs b/graphics/fbbootlogd/src/display.rs
index d276a24038..a26f0fc578 100644
--- a/graphics/fbbootlogd/src/display.rs
+++ b/graphics/fbbootlogd/src/display.rs
@@ -5,7 +5,6 @@ use libredox::errno::ESTALE;
 use orbclient::Event;
 use std::mem;
 use std::os::fd::BorrowedFd;
-use std::sync::mpsc::{self, Receiver, Sender};
 use std::sync::{Arc, Mutex};
 use std::{io, os::unix::io::AsRawFd, slice};
 
@@ -35,12 +34,7 @@ pub struct DisplayMap {
     pub inner: graphics_ipc::v1::DisplayMap,
 }
 
-enum DisplayCommand {
-    SyncRects(Vec<Damage>),
-}
-
 pub struct Display {
-    cmd_tx: Sender<DisplayCommand>,
     pub map: Arc<Mutex<Option<DisplayMap>>>,
 }
 
@@ -67,13 +61,7 @@ impl Display {
             Self::handle_input_events(map_clone, input_handle);
         });
 
-        let (cmd_tx, cmd_rx) = mpsc::channel();
-        let map_clone = map.clone();
-        std::thread::spawn(move || {
-            Self::handle_sync_rect(map_clone, cmd_rx);
-        });
-
-        Ok(Self { cmd_tx, map })
+        Ok(Self { map })
     }
 
     fn handle_input_events(map: Arc<Mutex<Option<DisplayMap>>>, input_handle: ConsumerHandle) {
@@ -129,26 +117,9 @@ impl Display {
         }
     }
 
-    fn handle_sync_rect(map: Arc<Mutex<Option<DisplayMap>>>, cmd_rx: Receiver<DisplayCommand>) {
-        while let Ok(cmd) = cmd_rx.recv() {
-            match cmd {
-                DisplayCommand::SyncRects(sync_rects) => {
-                    // We may not hold this lock across the write call to avoid deadlocking if the
-                    // graphics driver tries to write to the bootlog.
-                    let display_handle = if let Some(map) = &*map.lock().unwrap() {
-                        map.display_handle.clone()
-                    } else {
-                        continue;
-                    };
-                    display_handle.sync_rects(&sync_rects).unwrap();
-                }
-            }
+    pub fn sync_rects(&mut self, sync_rects: Vec<Damage>) {
+        if let Some(map) = &*self.map.lock().unwrap() {
+            map.display_handle.sync_rects(&sync_rects).unwrap();
         }
     }
-
-    pub fn sync_rects(&mut self, sync_rects: Vec<Damage>) {
-        self.cmd_tx
-            .send(DisplayCommand::SyncRects(sync_rects))
-            .unwrap();
-    }
 }
diff --git a/graphics/fbbootlogd/src/main.rs b/graphics/fbbootlogd/src/main.rs
index 1b0d941362..b566a76df4 100644
--- a/graphics/fbbootlogd/src/main.rs
+++ b/graphics/fbbootlogd/src/main.rs
@@ -1,13 +1,11 @@
 //! Fbbootlogd renders the boot log and presents it on VT1.
 //!
-//! While fbbootlogd is superficially similar to fbcond, there are two major differences:
+//! While fbbootlogd is superficially similar to fbcond, the major difference is:
 //!
 //! * Fbbootlogd doesn't accept input coming from the keyboard. It only allows getting written to.
-//! * Writing to fbbootlogd will never block. Not even on the graphics driver or inputd. This makes
-//!   it safe for graphics drivers and inputd to write to the boot log without risking deadlocks.
-//!   Fbcond will block on the graphics driver during handoff and will continously block on inputd
-//!   to get new input. Fbbootlogd does all blocking operations in background threads such that the
-//!   main thread will always keep accepting new input and writing it to the framebuffer.
+//!
+//! In the future fbbootlogd may also pull from logd as opposed to have logd push logs to it. And it
+//! it could display a boot splash like plymouth instead of a boot log when booting in quiet mode.
 
 use redox_scheme::{RequestKind, SignalBehavior, Socket};