3 files changed, 35 insertions, 9 deletions

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 1bafb40ec8a2..69ae5972713c 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -40,6 +40,7 @@
 #include <linux/init.h>
 #include <linux/miscdevice.h>
 #include <linux/delay.h>
+#include <linux/slab.h>
 #include <asm/uaccess.h>
 
 
@@ -52,8 +53,12 @@ static struct hwrng *current_rng;
 static LIST_HEAD(rng_list);
 static DEFINE_MUTEX(rng_mutex);
 static int data_avail;
-static u8 rng_buffer[SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES]
-        __cacheline_aligned;
+static u8 *rng_buffer;
+
+static size_t rng_buffer_size(void)
+{
+        return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
+}
 
 static inline int hwrng_init(struct hwrng *rng)
 {
@@ -116,7 +121,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 
                 if (!data_avail) {
                         bytes_read = rng_get_data(current_rng, rng_buffer,
-                                sizeof(rng_buffer),
+                                rng_buffer_size(),
                                 !(filp->f_flags & O_NONBLOCK));
                         if (bytes_read < 0) {
                                 err = bytes_read;
@@ -307,6 +312,14 @@ int hwrng_register(struct hwrng *rng)
 
         mutex_lock(&rng_mutex);
 
+        /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
+        err = -ENOMEM;
+        if (!rng_buffer) {
+                rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
+                if (!rng_buffer)
+                        goto out_unlock;
+        }
+
         /* Must not register two RNGs with the same name. */
         err = -EEXIST;
         list_for_each_entry(tmp, &rng_list, list) {
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 10fd71ccf587..6bf4d47324eb 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -92,14 +92,22 @@ static int probe_common(struct virtio_device *vdev)
 {
         int err;
 
+        if (vq) {
+                /* We only support one device for now */
+                return -EBUSY;
+        }
         /* We expect a single virtqueue. */
         vq = virtio_find_single_vq(vdev, random_recv_done, "input");
-        if (IS_ERR(vq))
-                return PTR_ERR(vq);
+        if (IS_ERR(vq)) {
+                err = PTR_ERR(vq);
+                vq = NULL;
+                return err;
+        }
 
         err = hwrng_register(&virtio_hwrng);
         if (err) {
                 vdev->config->del_vqs(vdev);
+                vq = NULL;
                 return err;
         }
 
@@ -112,6 +120,7 @@ static void remove_common(struct virtio_device *vdev)
         busy = false;
         hwrng_unregister(&virtio_hwrng);
         vdev->config->del_vqs(vdev);
+        vq = NULL;
 }
 
 static int virtrng_probe(struct virtio_device *vdev)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index 594bda9dcfc8..32a6c5764950 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -852,6 +852,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
                       int reserved)
 {
         unsigned long flags;
+        int wakeup_write = 0;
 
         /* Hold lock while accounting */
         spin_lock_irqsave(&r->lock, flags);
@@ -873,10 +874,8 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
                 else
                         r->entropy_count = reserved;
 
-                if (r->entropy_count < random_write_wakeup_thresh) {
-                        wake_up_interruptible(&random_write_wait);
-                        kill_fasync(&fasync, SIGIO, POLL_OUT);
-                }
+                if (r->entropy_count < random_write_wakeup_thresh)
+                        wakeup_write = 1;
         }
 
         DEBUG_ENT("debiting %zu entropy credits from %s%s\n",
@@ -884,6 +883,11 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
 
         spin_unlock_irqrestore(&r->lock, flags);
 
+        if (wakeup_write) {
+                wake_up_interruptible(&random_write_wait);
+                kill_fasync(&fasync, SIGIO, POLL_OUT);
+        }
+
         return nbytes;
 }