VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Thomas Gleixner <tglx@linutronix.de> 2021-09-23 18:54:43 +0200 committer: Minda Chen <minda.chen@starfivetech.com> 2023-11-06 19:24:42 +0800 commit: 001a685c0b2e89fa8e4186dc067a9e1ee833f5fa parent: eae2ac3e9136a15c1a7293b1b529c7c7be9154d9
Commit Summary:
sched: Make RCU nest depth distinct in __might_resched()
Diffstat:
3 files changed, 18 insertions, 13 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index f95ee786e4ef..e8696e4a45aa 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -111,7 +111,7 @@ static __always_inline void might_resched(void)
 #endif /* CONFIG_PREEMPT_* */
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
-extern void __might_resched(const char *file, int line, int preempt_offset);
+extern void __might_resched(const char *file, int line, unsigned int offsets);
 extern void __might_sleep(const char *file, int line);
 extern void __cant_sleep(const char *file, int line, int preempt_offset);
 extern void __cant_migrate(const char *file, int line);
@@ -169,7 +169,7 @@ extern void __cant_migrate(const char *file, int line);
 # define non_block_end() WARN_ON(current->non_block_count-- == 0)
 #else
   static inline void __might_resched(const char *file, int line,
-				     int preempt_offset) { }
+				     unsigned int offsets) { }
 static inline void __might_sleep(const char *file, int line) { }
 # define might_sleep() do { might_resched(); } while (0)
 # define cant_sleep() do { } while (0)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 64e9bdb5d523..4dde5e26de8f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2057,6 +2057,9 @@ extern int __cond_resched_lock(spinlock_t *lock);
 extern int __cond_resched_rwlock_read(rwlock_t *lock);
 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);					\
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index df94ab2f10ea..df2f0b53be15 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9468,12 +9468,6 @@ void __init sched_init(void)
 }
 
 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
-static inline int preempt_count_equals(int preempt_offset)
-{
-	int nested = preempt_count() + rcu_preempt_depth();
-
-	return (nested == preempt_offset);
-}
 
 void __might_sleep(const char *file, int line)
 {
@@ -9505,7 +9499,16 @@ static void print_preempt_disable_ip(int preempt_offset, unsigned long ip)
 	print_ip_sym(KERN_ERR, ip);
 }
 
-void __might_resched(const char *file, int line, int preempt_offset)
+static inline bool resched_offsets_ok(unsigned int offsets)
+{
+	unsigned int nested = preempt_count();
+
+	nested += rcu_preempt_depth() << MIGHT_RESCHED_RCU_SHIFT;
+
+	return nested == offsets;
+}
+
+void __might_resched(const char *file, int line, unsigned int offsets)
 {
 	/* Ratelimiting timestamp: */
 	static unsigned long prev_jiffy;
@@ -9515,7 +9518,7 @@ void __might_resched(const char *file, int line, int preempt_offset)
 	/* WARN_ON_ONCE() by default, no rate limit required: */
 	rcu_sleep_check();
 
-	if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
+	if ((resched_offsets_ok(offsets) && !irqs_disabled() &&
 	     !is_idle_task(current) && !current->non_block_count) ||
 	    system_state == SYSTEM_BOOTING || system_state > SYSTEM_RUNNING ||
 	    oops_in_progress)
@@ -9534,11 +9537,11 @@ void __might_resched(const char *file, int line, int preempt_offset)
 	       in_atomic(), irqs_disabled(), current->non_block_count,
 	       current->pid, current->comm);
 	pr_err("preempt_count: %x, expected: %x\n", preempt_count(),
-	       preempt_offset);
+	       offsets & MIGHT_RESCHED_PREEMPT_MASK);
 
 	if (IS_ENABLED(CONFIG_PREEMPT_RCU)) {
-		pr_err("RCU nest depth: %d, expected: 0\n",
-		       rcu_preempt_depth());
+		pr_err("RCU nest depth: %d, expected: %u\n",
+		       rcu_preempt_depth(), offsets >> MIGHT_RESCHED_RCU_SHIFT);
 	}
 
 	if (task_stack_end_corrupted(current))
@@ -9548,7 +9551,8 @@ void __might_resched(const char *file, int line, int preempt_offset)
 	if (irqs_disabled())
 		print_irqtrace_events(current);
 
-	print_preempt_disable_ip(preempt_offset, preempt_disable_ip);
+	print_preempt_disable_ip(offsets & MIGHT_RESCHED_PREEMPT_MASK,
+				 preempt_disable_ip);
 
 	dump_stack();
 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);