From: "Jason A. Donenfeld" Jason@zx2c4.com
stable inclusion from stable-v5.10.148 commit c1a4423fd30f6ff4289be19786c9e76b5ac104a6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0WL
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 9ee0507e896b45af6d65408c77815800bce30008 upstream.
In order to avoid reading and dirtying two cache lines on every IRQ, move the work_struct to the bottom of the fast_pool struct. add_ interrupt_randomness() always touches .pool and .count, which are currently split, because .mix pushes everything down. Instead, move .mix to the bottom, so that .pool and .count are always in the first cache line, since .mix is only accessed when the pool is full.
Fixes: 58340f8e952b ("random: defer fast pool mixing to worker") Reviewed-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com Reviewed-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/char/random.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c index a9cacf9a8cbb..bd51114bfda8 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -895,10 +895,10 @@ void __cold add_bootloader_randomness(const void *buf, size_t len) EXPORT_SYMBOL_GPL(add_bootloader_randomness);
struct fast_pool { - struct work_struct mix; unsigned long pool[4]; unsigned long last; unsigned int count; + struct work_struct mix; };
static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {