[PATCH] hwspinlock: improve locking safety by using raw_spinlock_t

[Wen Yang]

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.y...@linux.dev>
Cc: Bjorn Andersson <anders...@kernel.org>
Cc: Baolin Wang <baolin.w...@linux.alibaba.com>
Cc: Dave Young <dyo...@redhat.com>
Cc: linux-remotep...@vger.kernel.org
Cc: linux-kernel@vger.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