From: "Stephan Müller" <smueller@chronox.de>
To: Ted Tso <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Subject: [PATCH 4/8] random: remove unused branch in hot code path
Date: Tue, 27 Dec 2016 23:40:23 +0100 [thread overview]
Message-ID: <3380804.uZWydldqLU@positron.chronox.de> (raw)
In-Reply-To: <3254875.f5A5oHPdxF@positron.chronox.de>
The variable ip is defined to be a __u64 which is always 8 bytes on any
architecture. Thus, the check for sizeof(ip) > 4 will always be true.
As the check happens in a hot code path, remove the branch.
Signed-off-by: Stephan Mueller <smueller@chronox.de>
---
drivers/char/random.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 5c26b1c..8d4d720 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1136,8 +1136,7 @@ void add_interrupt_randomness(int irq, int irq_flags)
fast_pool->pool[1] ^= now ^ c_high;
ip = regs ? instruction_pointer(regs) : _RET_IP_;
fast_pool->pool[2] ^= ip;
- fast_pool->pool[3] ^= (sizeof(ip) > 4) ? ip >> 32 :
- get_reg(fast_pool, regs);
+ fast_pool->pool[3] ^= ip >> 32;
fast_mix(fast_pool);
add_interrupt_bench(cycles);
--
2.9.3
next prev parent reply other threads:[~2016-12-27 22:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-27 22:38 [PATCH 0/8] random: cleanup of code after removal of nonblocking pool Stephan Müller
2016-12-27 22:39 ` [PATCH 1/8] random: remove stale maybe_reseed_primary_crng Stephan Müller
2016-12-27 22:39 ` [PATCH 2/8] random: remove stale urandom_init_wait Stephan Müller
2016-12-27 22:39 ` [PATCH 3/8] random: trigger random_ready callback upon crng_init == 1 Stephan Müller
2017-01-18 4:12 ` Theodore Ts'o
2017-01-18 17:09 ` Stephan Müller
2016-12-27 22:40 ` Stephan Müller [this message]
2017-01-18 4:35 ` [PATCH 4/8] random: remove unused branch in hot code path Theodore Ts'o
2017-04-27 11:23 ` Geert Uytterhoeven
2016-12-27 22:40 ` [PATCH 5/8] random: remove variable limit Stephan Müller
2016-12-27 22:41 ` [PATCH 6/8] random: fix comment for unused random_min_urandom_seed Stephan Müller
2016-12-27 22:41 ` [PATCH 7/8] random: remove noop function call to xfer_secondary_pool Stephan Müller
2017-01-18 16:10 ` Theodore Ts'o
2016-12-27 22:42 ` [PATCH 8/8] random: move FIPS continuous test to output functions Stephan Müller
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