linux-kernel - [PATCH v2 05/35] thread_info: selector for TIF_NEED_RESCHED[

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Mon, 27 May 2024 17:34:51 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, peterz@...radead.org, torvalds@...ux-foundation.org,
        paulmck@...nel.org, rostedt@...dmis.org, mark.rutland@....com,
        juri.lelli@...hat.com, joel@...lfernandes.org, raghavendra.kt@....com,
        sshegde@...ux.ibm.com, boris.ostrovsky@...cle.com,
        konrad.wilk@...cle.com, Ankur Arora <ankur.a.arora@...cle.com>
Subject: [PATCH v2 05/35] thread_info: selector for TIF_NEED_RESCHED[_LAZY]

Define tif_resched() to serve as selector for the specific
need-resched flag: with tif_resched() mapping to TIF_NEED_RESCHED
or to TIF_NEED_RESCHED_LAZY.

For !CONFIG_PREEMPT_AUTO, tif_resched() always evaluates
to TIF_NEED_RESCHED, preserving existing scheduling behaviour.

Cc: Peter Ziljstra <peterz@...radead.org>
Originally-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/lkml/87jzshhexi.ffs@tglx/
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 include/linux/thread_info.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 06e13e7acbe2..65e5beedc915 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -71,6 +71,31 @@ enum syscall_work_bit {
 #define _TIF_NEED_RESCHED_LAZY _TIF_NEED_RESCHED
 #endif
 
+typedef enum {
+	RESCHED_NOW = 0,
+	RESCHED_LAZY = 1,
+} resched_t;
+
+/*
+ * tif_resched(r) maps to TIF_NEED_RESCHED[_LAZY] with CONFIG_PREEMPT_AUTO.
+ *
+ * For !CONFIG_PREEMPT_AUTO, both tif_resched(RESCHED_NOW) and
+ * tif_resched(RESCHED_LAZY) reduce to the same value (TIF_NEED_RESCHED)
+ * leaving any scheduling behaviour unchanged.
+ */
+static __always_inline int tif_resched(resched_t rs)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT_AUTO))
+		return (rs == RESCHED_NOW) ? TIF_NEED_RESCHED : TIF_NEED_RESCHED_LAZY;
+	else
+		return TIF_NEED_RESCHED;
+}
+
+static __always_inline int _tif_resched(resched_t rs)
+{
+	return 1 << tif_resched(rs);
+}
+
 #ifdef __KERNEL__
 
 #ifndef arch_set_restart_data
-- 
2.31.1