Re: [PATCH 2/2] virtio-rng: fix stuck in catting hwrng attributes

2014-09-14 10:25+0800, Amos Kong:

On Sun, Sep 14, 2014 at 09:12:08AM +0800, Amos Kong wrote:

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diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index c591d7e..b5d1b6f 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c

@@ -195,8 +195,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 
 		mutex_unlock(&rng_mutex);
 
-		if (need_resched())
-			schedule_timeout_interruptible(1);
+		schedule_timeout_interruptible(10);

If cond_resched() does not work, it is a bug elsewehere.

Problem only occurred in non-smp guest, we can improve it to:

                        if(!is_smp())
                                schedule_timeout_interruptible(10);

is_smp() is only available for arm arch, we need a general one.

(It is num_online_cpus() > 1.)