author: Thomas Gleixner <tglx@linutronix.de> 2021-09-23 18:54:44 +0200
committer: Minda Chen <minda.chen@starfivetech.com> 2023-11-06 19:24:43 +0800
commit: d24dda5fcf99e6d3b86107a9dd94d69c2cc2be34
parent: 001a685c0b2e89fa8e4186dc067a9e1ee833f5fa
Commit Summary:
Diffstat:
2 files changed, 27 insertions, 11 deletions
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 4d244e295e85..031898b38d06 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -122,9 +122,10 @@
* The preempt_count offset after spin_lock()
*/
#if !defined(CONFIG_PREEMPT_RT)
-#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET
+#define PREEMPT_LOCK_OFFSET PREEMPT_DISABLE_OFFSET
#else
-#define PREEMPT_LOCK_OFFSET 0
+/* Locks on RT do not disable preemption */
+#define PREEMPT_LOCK_OFFSET 0
#endif
/*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4dde5e26de8f..2b8c8150792c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2060,19 +2060,35 @@ extern int __cond_resched_rwlock_write(rwlock_t *lock);
#define MIGHT_RESCHED_RCU_SHIFT 8
#define MIGHT_RESCHED_PREEMPT_MASK ((1U << MIGHT_RESCHED_RCU_SHIFT) - 1)
-#define cond_resched_lock(lock) ({ \
- __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
- __cond_resched_lock(lock); \
+#ifndef CONFIG_PREEMPT_RT
+/*
+ * Non RT kernels have an elevated preempt count due to the held lock,
+ * but are not allowed to be inside a RCU read side critical section
+ */
+# define PREEMPT_LOCK_RESCHED_OFFSETS PREEMPT_LOCK_OFFSET
+#else
+/*
+ * spin/rw_lock() on RT implies rcu_read_lock(). The might_sleep() check in
+ * cond_resched*lock() has to take that into account because it checks for
+ * preempt_count() and rcu_preempt_depth().
+ */
+# define PREEMPT_LOCK_RESCHED_OFFSETS \
+ (PREEMPT_LOCK_OFFSET + (1U << MIGHT_RESCHED_RCU_SHIFT))
+#endif
+
+#define cond_resched_lock(lock) ({ \
+ __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_RESCHED_OFFSETS); \
+ __cond_resched_lock(lock); \
})
-#define cond_resched_rwlock_read(lock) ({ \
- __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
- __cond_resched_rwlock_read(lock); \
+#define cond_resched_rwlock_read(lock) ({ \
+ __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_RESCHED_OFFSETS); \
+ __cond_resched_rwlock_read(lock); \
})
-#define cond_resched_rwlock_write(lock) ({ \
- __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET); \
- __cond_resched_rwlock_write(lock); \
+#define cond_resched_rwlock_write(lock) ({ \
+ __might_resched(__FILE__, __LINE__, PREEMPT_LOCK_RESCHED_OFFSETS); \
+ __cond_resched_rwlock_write(lock); \
})
static inline void cond_resched_rcu(void)