1 files changed, 22 insertions, 44 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 20e9887faaaa..fb77f7bfd126 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -750,60 +750,38 @@ static int __init debug_boot_weak_hash_enable(char *str)
 }
 early_param("debug_boot_weak_hash", debug_boot_weak_hash_enable);
 
-static DEFINE_STATIC_KEY_TRUE(not_filled_random_ptr_key);
-static siphash_key_t ptr_key __read_mostly;
+static DEFINE_STATIC_KEY_FALSE(filled_random_ptr_key);
 
 static void enable_ptr_key_workfn(struct work_struct *work)
 {
-	get_random_bytes(&ptr_key, sizeof(ptr_key));
-	/* Needs to run from preemptible context */
-	static_branch_disable(&not_filled_random_ptr_key);
+	static_branch_enable(&filled_random_ptr_key);
 }
 
-static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
-
-static int fill_random_ptr_key(struct notifier_block *nb,
-			       unsigned long action, void *data)
-{
-	/* This may be in an interrupt handler. */
-	queue_work(system_unbound_wq, &enable_ptr_key_work);
-	return 0;
-}
-
-static struct notifier_block random_ready = {
-	.notifier_call = fill_random_ptr_key
-};
-
-static int __init initialize_ptr_random(void)
-{
-	int ret;
-
-	/* Don't bother waiting for RNG to be ready if RDRAND is mixed in already. */
-	if (rng_has_arch_random()) {
-		enable_ptr_key_workfn(&enable_ptr_key_work);
-		return 0;
-	}
-
-	ret = register_random_ready_notifier(&random_ready);
-	if (!ret) {
-		return 0;
-	} else if (ret == -EALREADY) {
-		/* This is in preemptible context */
-		enable_ptr_key_workfn(&enable_ptr_key_work);
-		return 0;
-	}
-
-	return ret;
-}
-early_initcall(initialize_ptr_random);
-
 /* Maps a pointer to a 32 bit unique identifier. */
 static inline int __ptr_to_hashval(const void *ptr, unsigned long *hashval_out)
 {
+	static siphash_key_t ptr_key __read_mostly;
 	unsigned long hashval;
 
-	if (static_branch_unlikely(&not_filled_random_ptr_key))
-		return -EAGAIN;
+	if (!static_branch_likely(&filled_random_ptr_key)) {
+		static bool filled = false;
+		static DEFINE_SPINLOCK(filling);
+		static DECLARE_WORK(enable_ptr_key_work, enable_ptr_key_workfn);
+		unsigned long flags;
+
+		if (!system_unbound_wq ||
+		    (!rng_is_initialized() && !rng_has_arch_random()) ||
+		    !spin_trylock_irqsave(&filling, flags))
+			return -EAGAIN;
+
+		if (!filled) {
+			get_random_bytes(&ptr_key, sizeof(ptr_key));
+			queue_work(system_unbound_wq, &enable_ptr_key_work);
+			filled = true;
+		}
+		spin_unlock_irqrestore(&filling, flags);
+	}
+
 
 #ifdef CONFIG_64BIT
 	hashval = (unsigned long)siphash_1u64((u64)ptr, &ptr_key);