linux-kernel - [PATCH] random: add 8-bit and 16-bit batches

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Message-Id: <20220928165018.73496-1-Jason@zx2c4.com>
Date:   Wed, 28 Sep 2022 18:50:18 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH] random: add 8-bit and 16-bit batches

There are numerous places in the kernel that would be sped up by having
smaller batches. Currently those callsites do `get_random_u32() & 0xff`
or similar. Since these are pretty spread out, and will require patches
to multiple different trees, let's get ahead of the curve and lay the
foundation for `get_random_u8()` and `get_random_u16()`, so that it's
then possible to start submitting conversion patches leisurely.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/char/random.c  | 2 ++
 include/linux/random.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index f2aa3ab1b458..64ee16ffb8b7 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -506,6 +506,8 @@ EXPORT_SYMBOL(get_random_ ##type);

 DEFINE_BATCHED_ENTROPY(u64)
 DEFINE_BATCHED_ENTROPY(u32)
+DEFINE_BATCHED_ENTROPY(u16)
+DEFINE_BATCHED_ENTROPY(u8)

 #ifdef CONFIG_SMP
 /*
diff --git a/include/linux/random.h b/include/linux/random.h
index a9e6e16f9774..2c130f8f18e5 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -38,6 +38,8 @@ static inline int unregister_random_vmfork_notifier(struct notifier_block *nb) {
 #endif

 void get_random_bytes(void *buf, size_t len);
+u8 get_random_u8(void);
+u16 get_random_u16(void);
 u32 get_random_u32(void);
 u64 get_random_u64(void);
 static inline unsigned int get_random_int(void)
-- 
2.37.3