linux-kernel - [PATCH 1/2] random: move fast_pool/fast

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Date:   Thu, 10 Feb 2022 17:09:24 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     linux@...inikbrodowski.net, linux-kernel@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Theodore Ts'o <tytso@....edu>
Subject: [PATCH 1/2] random: move fast_pool/fast_mix definitions to site of use

No actual code changes, just code position changes. Having to scroll up
and down by several hundred lines every time is confusing and hard to
follow. Instead cluster these together. Later when we're redocumenting
the file, it'll mean a smaller delta.

Cc: Theodore Ts'o <tytso@....edu>
Cc: Dominik Brodowski <linux@...inikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/char/random.c | 101 +++++++++++++++++++++---------------------
 1 file changed, 51 insertions(+), 50 deletions(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 77131f7b0f06..923a8f861437 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -281,45 +281,6 @@ static void mix_pool_bytes(const void *in, size_t nbytes)
 	spin_unlock_irqrestore(&input_pool.lock, flags);
 }
 
-struct fast_pool {
-	struct work_struct mix;
-	unsigned long last;
-	u32 pool[4];
-	unsigned int count;
-	u16 reg_idx;
-};
-#define FAST_POOL_MIX_INFLIGHT (1U << 31)
-
-/*
- * This is a fast mixing routine used by the interrupt randomness
- * collector.  It's hardcoded for an 128 bit pool and assumes that any
- * locks that might be needed are taken by the caller.
- */
-static void fast_mix(struct fast_pool *f)
-{
-	u32 a = f->pool[0],	b = f->pool[1];
-	u32 c = f->pool[2],	d = f->pool[3];
-
-	a += b;			c += d;
-	b = rol32(b, 6);	d = rol32(d, 27);
-	d ^= a;			b ^= c;
-
-	a += b;			c += d;
-	b = rol32(b, 16);	d = rol32(d, 14);
-	d ^= a;			b ^= c;
-
-	a += b;			c += d;
-	b = rol32(b, 6);	d = rol32(d, 27);
-	d ^= a;			b ^= c;
-
-	a += b;			c += d;
-	b = rol32(b, 16);	d = rol32(d, 14);
-	d ^= a;			b ^= c;
-
-	f->pool[0] = a;  f->pool[1] = b;
-	f->pool[2] = c;  f->pool[3] = d;
-}
-
 static void process_random_ready_list(void)
 {
 	unsigned long flags;
@@ -758,6 +719,57 @@ void add_input_randomness(unsigned int type, unsigned int code,
 }
 EXPORT_SYMBOL_GPL(add_input_randomness);
 
+#ifdef CONFIG_BLOCK
+void add_disk_randomness(struct gendisk *disk)
+{
+	if (!disk || !disk->random)
+		return;
+	/* first major is 1, so we get >= 0x200 here */
+	add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
+}
+EXPORT_SYMBOL_GPL(add_disk_randomness);
+#endif
+
+struct fast_pool {
+	struct work_struct mix;
+	unsigned long last;
+	u32 pool[4];
+	unsigned int count;
+	u16 reg_idx;
+};
+#define FAST_POOL_MIX_INFLIGHT (1U << 31)
+
+/*
+ * This is a fast mixing routine used by the interrupt randomness
+ * collector. It's hardcoded for an 128 bit pool and assumes that any
+ * locks that might be needed are taken by the caller.
+ */
+static void fast_mix(struct fast_pool *f)
+{
+	u32 a = f->pool[0],	b = f->pool[1];
+	u32 c = f->pool[2],	d = f->pool[3];
+
+	a += b;			c += d;
+	b = rol32(b, 6);	d = rol32(d, 27);
+	d ^= a;			b ^= c;
+
+	a += b;			c += d;
+	b = rol32(b, 16);	d = rol32(d, 14);
+	d ^= a;			b ^= c;
+
+	a += b;			c += d;
+	b = rol32(b, 6);	d = rol32(d, 27);
+	d ^= a;			b ^= c;
+
+	a += b;			c += d;
+	b = rol32(b, 16);	d = rol32(d, 14);
+	d ^= a;			b ^= c;
+
+	f->pool[0] = a;  f->pool[1] = b;
+	f->pool[2] = c;  f->pool[3] = d;
+}
+
+
 static DEFINE_PER_CPU(struct fast_pool, irq_randomness);
 
 static u32 get_reg(struct fast_pool *f, struct pt_regs *regs)
@@ -849,17 +861,6 @@ void add_interrupt_randomness(int irq)
 }
 EXPORT_SYMBOL_GPL(add_interrupt_randomness);
 
-#ifdef CONFIG_BLOCK
-void add_disk_randomness(struct gendisk *disk)
-{
-	if (!disk || !disk->random)
-		return;
-	/* first major is 1, so we get >= 0x200 here */
-	add_timer_randomness(disk->random, 0x100 + disk_devt(disk));
-}
-EXPORT_SYMBOL_GPL(add_disk_randomness);
-#endif
-
 /*********************************************************************
  *
  * Entropy extraction routines
-- 
2.35.0