[plasma/plasma-login-manager/Plasma/6.7] src: Revert "VirtualTerminal: take over stale VT_PROCESS handler and ignore VT switch signals during the session handoff"

Git commit f774f15ac3228355b1a040b430d091e02103405c by Dustin Kadrmas.
Committed on 16/07/2026 at 21:17.
Pushed by davidedmundson into branch 'Plasma/6.7'.

Revert "VirtualTerminal: take over stale VT_PROCESS handler and ignore VT switch signals during the session handoff"

This reverts commit b49a7c471e05f7c5f098c0e16461ca5133380d08.

The takeover fires on every VT handoff, not only the stuck case it was
written for: it acknowledges the VT release before logind has paused the
outgoing session's devices, so on a normal logout the incoming greeter's
compositor finds the DRM device still busy and logout lands on a text
console. Fedora reproduced this in openQA against 6.7.3 and confirmed
reverting this commit clears it; Fedora is already carrying the revert
downstream.

A corrected approach is proposed against master (!170). The stable
branch should carry the known-safe state meanwhile.

M  +0    -19   src/common/VirtualTerminal.cpp
M  +0    -1    src/common/VirtualTerminal.h
M  +0    -3    src/helper/UserSession.cpp

https://invent.kde.org/plasma/plasma-login-manager/-/commit/f774f15ac3228355b1a040b430d091e02103405c

diff --git a/src/common/VirtualTerminal.cpp b/src/common/VirtualTerminal.cpp
index 8522128c..0b71cb5b 100644
--- a/src/common/VirtualTerminal.cpp
+++ b/src/common/VirtualTerminal.cpp
@@ -87,17 +87,6 @@ static bool handleVtSwitches(int fd)
     return ok;
 }
 
-void ignoreVtSwitches()
-{
-    // For callers that execve() while still the VT_PROCESS owner:
-    // handled dispositions reset to SIG_DFL across exec, so a switch
-    // request in the window before the new compositor takes VT control
-    // would kill the process. SIG_IGN survives exec; the kernel defers
-    // the switch until the compositor re-establishes VT handling.
-    signal(RELEASE_DISPLAY_SIGNAL, SIG_IGN);
-    signal(ACQUIRE_DISPLAY_SIGNAL, SIG_IGN);
-}
-
 static void fixVtMode(int fd, bool vt_auto)
 {
     vt_mode getmodeReply{};
@@ -110,14 +99,6 @@ static void fixVtMode(int fd, bool vt_auto)
         ok = false;
     }
 
-    // The previous VT_PROCESS owner (logind for Wayland greeters)
-    // can clear its VT mode mid-switch, leaving VT_WAITACTIVE hung.
-    // Take over so the relsig handshake completes locally.
-    if (getmodeReply.mode == VT_PROCESS) {
-        ok = handleVtSwitches(fd);
-        modeFixed = true;
-    }
-
     if (getmodeReply.mode != VT_AUTO) {
         goto out;
     }
diff --git a/src/common/VirtualTerminal.h b/src/common/VirtualTerminal.h
index 874af5d8..16a37be9 100644
--- a/src/common/VirtualTerminal.h
+++ b/src/common/VirtualTerminal.h
@@ -29,7 +29,6 @@ QString path(int vt);
 int currentVt();
 int setUpNewVt();
 void jumpToVt(int vt, bool vt_auto);
-void ignoreVtSwitches();
 }
 }
 
diff --git a/src/helper/UserSession.cpp b/src/helper/UserSession.cpp
index 26569e22..9c1bb342 100644
--- a/src/helper/UserSession.cpp
+++ b/src/helper/UserSession.cpp
@@ -146,9 +146,6 @@ void UserSession::childModifier()
 
     if (vtNumber > 0) {
         VirtualTerminal::jumpToVt(vtNumber, x11Session);
-        // This process becomes the session via execve(); leave the VT
-        // switch signals ignored so they survive the exec.
-        VirtualTerminal::ignoreVtSwitches();
     }
 
 #ifdef Q_OS_LINUX