Merge pull request #263206 from kanashimia/revert-259066-add-renice-sway

Revert "nixos/sway: add enableRealtime option"

nixos/modules/programs/wayland/sway.nix

···
       <https://github.com/swaywm/sway/wiki> and
       "man 5 sway" for more information'');
 
-    enableRealtime = mkEnableOption (lib.mdDoc ''
-      add CAP_SYS_NICE capability on `sway` binary for realtime scheduling
-      privileges. This may improve latency and reduce stuttering, specially in
-      high load scenarios'') // { default = true; };
-
     package = mkOption {
       type = with types; nullOr package;
       default = defaultSwayPackage;
···
             '';
           } // optionalAttrs (cfg.package != null) {
             "sway/config".source = mkOptionDefault "${cfg.package}/etc/sway/config";
-          };
-        };
-        security.wrappers = mkIf (cfg.enableRealtime && cfg.package != null) {
-          sway = {
-            owner = "root";
-            group = "root";
-            source = "${cfg.package}/bin/sway";
-            capabilities = "cap_sys_nice+ep";
           };
         };
         # To make a Sway session available if a display manager like SDDM is enabled:

pkgs/applications/window-managers/sway/default.nix

···
     # Use /run/current-system/sw/share and /etc instead of /nix/store
     # references:
     ./sway-config-nixos-paths.patch
-    # Drop ambient capabilities after getting SCHED_RR
-    ./drop_ambient_capabilities.patch
   ];
 
   strictDeps = true;

pkgs/applications/window-managers/sway/drop_ambient_capabilities.patch

···
-From e7d9098e81289ae99d07ec3eac1fec1d303b8fe4 Mon Sep 17 00:00:00 2001
-From: Thiago Kenji Okada <[e-mail]>
-Date: Thu, 5 Oct 2023 15:23:35 +0100
-Subject: [PATCH] drop ambient capabilities
-
-Within NixOS the only possibility to gain cap_sys_nice is using the
-security.wrapper infrastructure. However to pass the capabilities to the
-wrapped program, they are raised to the ambient set. To fix this we make
-sure to drop the ambient capabilities during sway startup and realtime
-setup. Otherwise all programs started by sway also gain cap_sys_nice,
-which is not something we want.
-
-Co-authored-by: Rouven Czerwinski <[e-mail]>
----
- sway/realtime.c | 3 +++
- 1 file changed, 3 insertions(+)
-
-diff --git a/sway/realtime.c b/sway/realtime.c
-index 11154af0..06f872a8 100644
---- a/sway/realtime.c
-+++ b/sway/realtime.c
-@@ -3,6 +3,7 @@
- #include <unistd.h>
- #include <pthread.h>
- #include "sway/server.h"
-+#include "sys/prctl.h"
- #include "log.h"
- 
- static void child_fork_callback(void) {
-@@ -10,6 +11,8 @@ static void child_fork_callback(void) {
- 
- 	param.sched_priority = 0;
- 
-+	prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_CLEAR_ALL, 0, 0, 0);
-+
- 	int ret = pthread_setschedparam(pthread_self(), SCHED_OTHER, &param);
- 	if (ret != 0) {
- 		sway_log(SWAY_ERROR, "Failed to reset scheduler policy on fork");
--- 
-2.42.0
-