alinux: random: speed up the initialization of module

anolis inclusion
from anolis_master
commit 7afda44c8a9e043f8f16dcc57dd8ef615522e2c8
category: performance
bugzilla: NA
CVE: NA
---------------------------

alinux: random: speed up the initialization of module

During the module initialization phase, entropy will be added
to entropy pool for every interrupt, the change should speed up
initialization of the random module.

Before optimization:
[   22.180236] random: crng init done

After optimization:
[    1.474832] random: crng init done
Signed-off-by: NXingjun Liu <xingjun.lxj@alibaba-inc.com>
Reviewed-by: NLiu Jiang <gerry@linux.alibaba.com>
Reviewed-by: NCaspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
Signed-off-by: NChen Jialong <chenjialong@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: NZiyuan Hu <huziyuan@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/char/random.c

@@ -1269,7 +1269,8 @@ void add_interrupt_randomness(int irq, int irq_flags)
 	}
 
 	if ((fast_pool->count < 64) &&
-	    !time_after(now, fast_pool->last + HZ))
+	    !time_after(now, fast_pool->last + HZ) &&
+	    crng_ready())
 		return;
 
 	r = &input_pool;