linux-kernel - [PATCH] hwspinlock: improve locking safety by using raw_spinlock

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Message-Id: <20240824143847.5307-1-wen.yang@linux.dev>
Date: Sat, 24 Aug 2024 22:38:47 +0800
From: Wen Yang <wen.yang@...ux.dev>
To: Bjorn Andersson <andersson@...nel.org>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Wen Yang <wen.yang@...ux.dev>,
	Dave Young <dyoung@...hat.com>,
	linux-remoteproc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] hwspinlock: improve locking safety by using raw_spinlock_t

Both __hwspin_trylock and __hwspin_unlock use hwlock->lock, and require
running in atomic context, with a special annotation:
function will never sleep.
However, this requirement is not fulfilled on PREEMPT_RT.

To address it, use raw_spinlock_t instead of spin_lock_t.

Signed-off-by: Wen Yang <wen.yang@...ux.dev>
Cc: Bjorn Andersson <andersson@...nel.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc: Dave Young <dyoung@...hat.com>
Cc: linux-remoteproc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/hwspinlock/hwspinlock_core.c     | 20 ++++++++++----------
 drivers/hwspinlock/hwspinlock_internal.h |  2 +-
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 6505261e6068..76e5a6c645b1 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -111,17 +111,17 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
 	 */
 	switch (mode) {
 	case HWLOCK_IRQSTATE:
-		ret = spin_trylock_irqsave(&hwlock->lock, *flags);
+		ret = raw_spin_trylock_irqsave(&hwlock->lock, *flags);
 		break;
 	case HWLOCK_IRQ:
-		ret = spin_trylock_irq(&hwlock->lock);
+		ret = raw_spin_trylock_irq(&hwlock->lock);
 		break;
 	case HWLOCK_RAW:
 	case HWLOCK_IN_ATOMIC:
 		ret = 1;
 		break;
 	default:
-		ret = spin_trylock(&hwlock->lock);
+		ret = raw_spin_trylock(&hwlock->lock);
 		break;
 	}
 
@@ -136,17 +136,17 @@ int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
 	if (!ret) {
 		switch (mode) {
 		case HWLOCK_IRQSTATE:
-			spin_unlock_irqrestore(&hwlock->lock, *flags);
+			raw_spin_unlock_irqrestore(&hwlock->lock, *flags);
 			break;
 		case HWLOCK_IRQ:
-			spin_unlock_irq(&hwlock->lock);
+			raw_spin_unlock_irq(&hwlock->lock);
 			break;
 		case HWLOCK_RAW:
 		case HWLOCK_IN_ATOMIC:
 			/* Nothing to do */
 			break;
 		default:
-			spin_unlock(&hwlock->lock);
+			raw_spin_unlock(&hwlock->lock);
 			break;
 		}
 
@@ -289,17 +289,17 @@ void __hwspin_unlock(struct hwspinlock *hwlock, int mode, unsigned long *flags)
 	/* Undo the spin_trylock{_irq, _irqsave} called while locking */
 	switch (mode) {
 	case HWLOCK_IRQSTATE:
-		spin_unlock_irqrestore(&hwlock->lock, *flags);
+		raw_spin_unlock_irqrestore(&hwlock->lock, *flags);
 		break;
 	case HWLOCK_IRQ:
-		spin_unlock_irq(&hwlock->lock);
+		raw_spin_unlock_irq(&hwlock->lock);
 		break;
 	case HWLOCK_RAW:
 	case HWLOCK_IN_ATOMIC:
 		/* Nothing to do */
 		break;
 	default:
-		spin_unlock(&hwlock->lock);
+		raw_spin_unlock(&hwlock->lock);
 		break;
 	}
 }
@@ -535,7 +535,7 @@ int hwspin_lock_register(struct hwspinlock_device *bank, struct device *dev,
 	for (i = 0; i < num_locks; i++) {
 		hwlock = &bank->lock[i];
 
-		spin_lock_init(&hwlock->lock);
+		raw_spin_lock_init(&hwlock->lock);
 		hwlock->bank = bank;
 
 		ret = hwspin_lock_register_single(hwlock, base_id + i);
diff --git a/drivers/hwspinlock/hwspinlock_internal.h b/drivers/hwspinlock/hwspinlock_internal.h
index f298fc0ee5ad..9fbd66e8a82f 100644
--- a/drivers/hwspinlock/hwspinlock_internal.h
+++ b/drivers/hwspinlock/hwspinlock_internal.h
@@ -42,7 +42,7 @@ struct hwspinlock_ops {
  */
 struct hwspinlock {
 	struct hwspinlock_device *bank;
-	spinlock_t lock;
+	raw_spinlock_t lock;
 	void *priv;
 };
 
-- 
2.25.1