linux-kernel - [PATCH v2 2/6] rcu: rename PREEMPT_AUTO to PREEMPT

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Message-Id: <20241106201758.428310-3-ankur.a.arora@oracle.com>
Date: Wed,  6 Nov 2024 12:17:54 -0800
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, tglx@...utronix.de, paulmck@...nel.org,
        mingo@...nel.org, bigeasy@...utronix.de, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        vschneid@...hat.com, frederic@...nel.org, ankur.a.arora@...cle.com,
        efault@....de, sshegde@...ux.ibm.com, boris.ostrovsky@...cle.com
Subject: [PATCH v2 2/6] rcu: rename PREEMPT_AUTO to PREEMPT_LAZY

Replace mentions of PREEMPT_AUTO with PREEMPT_LAZY.

Also, since PREMPT_LAZY implies PREEMPTION, we can just reduce the
TASKS_RCU selection criteria from:

  NEED_TASKS_RCU && (PREEMPTION || PREEMPT_AUTO)
to:
  NEED_TASKS_RCU && PREEMPTION

CC: Paul E. McKenney <paulmck@...nel.org>
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 include/linux/srcutiny.h |  2 +-
 kernel/rcu/Kconfig       |  2 +-
 kernel/rcu/srcutiny.c    | 14 +++++++-------
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 4d96bbdb45f0..1635c5e2662f 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -64,7 +64,7 @@ static inline int __srcu_read_lock(struct srcu_struct *ssp)
 {
 	int idx;
 
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	idx = ((READ_ONCE(ssp->srcu_idx) + 1) & 0x2) >> 1;
 	WRITE_ONCE(ssp->srcu_lock_nesting[idx], READ_ONCE(ssp->srcu_lock_nesting[idx]) + 1);
 	preempt_enable();
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 3e079de0f5b4..5a7ff5e1cdcb 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -91,7 +91,7 @@ config NEED_TASKS_RCU
 
 config TASKS_RCU
 	bool
-	default NEED_TASKS_RCU && (PREEMPTION || PREEMPT_AUTO)
+	default NEED_TASKS_RCU && PREEMPTION
 	select IRQ_WORK
 
 config FORCE_TASKS_RUDE_RCU
diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c
index 549c03336ee9..8a662d911abd 100644
--- a/kernel/rcu/srcutiny.c
+++ b/kernel/rcu/srcutiny.c
@@ -98,7 +98,7 @@ void __srcu_read_unlock(struct srcu_struct *ssp, int idx)
 {
 	int newval;
 
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	newval = READ_ONCE(ssp->srcu_lock_nesting[idx]) - 1;
 	WRITE_ONCE(ssp->srcu_lock_nesting[idx], newval);
 	preempt_enable();
@@ -120,7 +120,7 @@ void srcu_drive_gp(struct work_struct *wp)
 	struct srcu_struct *ssp;
 
 	ssp = container_of(wp, struct srcu_struct, srcu_work);
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	if (ssp->srcu_gp_running || ULONG_CMP_GE(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max))) {
 		return; /* Already running or nothing to do. */
 		preempt_enable();
@@ -138,7 +138,7 @@ void srcu_drive_gp(struct work_struct *wp)
 	WRITE_ONCE(ssp->srcu_gp_waiting, true);  /* srcu_read_unlock() wakes! */
 	preempt_enable();
 	swait_event_exclusive(ssp->srcu_wq, !READ_ONCE(ssp->srcu_lock_nesting[idx]));
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	WRITE_ONCE(ssp->srcu_gp_waiting, false); /* srcu_read_unlock() cheap. */
 	WRITE_ONCE(ssp->srcu_idx, ssp->srcu_idx + 1);
 	preempt_enable();
@@ -159,7 +159,7 @@ void srcu_drive_gp(struct work_struct *wp)
 	 * at interrupt level, but the ->srcu_gp_running checks will
 	 * straighten that out.
 	 */
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	WRITE_ONCE(ssp->srcu_gp_running, false);
 	idx = ULONG_CMP_LT(ssp->srcu_idx, READ_ONCE(ssp->srcu_idx_max));
 	preempt_enable();
@@ -172,7 +172,7 @@ static void srcu_gp_start_if_needed(struct srcu_struct *ssp)
 {
 	unsigned long cookie;
 
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	cookie = get_state_synchronize_srcu(ssp);
 	if (ULONG_CMP_GE(READ_ONCE(ssp->srcu_idx_max), cookie)) {
 		preempt_enable();
@@ -199,7 +199,7 @@ void call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
 
 	rhp->func = func;
 	rhp->next = NULL;
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	local_irq_save(flags);
 	*ssp->srcu_cb_tail = rhp;
 	ssp->srcu_cb_tail = &rhp->next;
@@ -261,7 +261,7 @@ unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp)
 {
 	unsigned long ret;
 
-	preempt_disable();  // Needed for PREEMPT_AUTO
+	preempt_disable();  // Needed for PREEMPT_LAZY
 	ret = get_state_synchronize_srcu(ssp);
 	srcu_gp_start_if_needed(ssp);
 	preempt_enable();
-- 
2.43.5