1 files changed, 31 insertions, 23 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index cd9a6211dcad..35487e8ded59 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -865,16 +865,24 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
         if (r->entropy_count / 8 < min + reserved) {
                 nbytes = 0;
         } else {
+                int entropy_count, orig;
+retry:
+                entropy_count = orig = ACCESS_ONCE(r->entropy_count);
                 /* If limited, never pull more than available */
-                if (r->limit && nbytes + reserved >= r->entropy_count / 8)
-                        nbytes = r->entropy_count/8 - reserved;
-
-                if (r->entropy_count / 8 >= nbytes + reserved)
-                        r->entropy_count -= nbytes*8;
-                else
-                        r->entropy_count = reserved;
+                if (r->limit && nbytes + reserved >= entropy_count / 8)
+                        nbytes = entropy_count/8 - reserved;
+
+                if (entropy_count / 8 >= nbytes + reserved) {
+                        entropy_count -= nbytes*8;
+                        if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+                                goto retry;
+                } else {
+                        entropy_count = reserved;
+                        if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
+                                goto retry;
+                }
 
-                if (r->entropy_count < random_write_wakeup_thresh)
+                if (entropy_count < random_write_wakeup_thresh)
                         wakeup_write = 1;
         }
 
@@ -957,10 +965,23 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
 {
         ssize_t ret = 0, i;
         __u8 tmp[EXTRACT_SIZE];
+        unsigned long flags;
 
         /* if last_data isn't primed, we need EXTRACT_SIZE extra bytes */
-        if (fips_enabled && !r->last_data_init)
-                nbytes += EXTRACT_SIZE;
+        if (fips_enabled) {
+                spin_lock_irqsave(&r->lock, flags);
+                if (!r->last_data_init) {
+                        r->last_data_init = true;
+                        spin_unlock_irqrestore(&r->lock, flags);
+                        trace_extract_entropy(r->name, EXTRACT_SIZE,
+                                              r->entropy_count, _RET_IP_);
+                        xfer_secondary_pool(r, EXTRACT_SIZE);
+                        extract_buf(r, tmp);
+                        spin_lock_irqsave(&r->lock, flags);
+                        memcpy(r->last_data, tmp, EXTRACT_SIZE);
+                }
+                spin_unlock_irqrestore(&r->lock, flags);
+        }
 
         trace_extract_entropy(r->name, nbytes, r->entropy_count, _RET_IP_);
         xfer_secondary_pool(r, nbytes);
@@ -970,19 +991,6 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
                 extract_buf(r, tmp);
 
                 if (fips_enabled) {
-                        unsigned long flags;
-
-
-                        /* prime last_data value if need be, per fips 140-2 */
-                        if (!r->last_data_init) {
-                                spin_lock_irqsave(&r->lock, flags);
-                                memcpy(r->last_data, tmp, EXTRACT_SIZE);
-                                r->last_data_init = true;
-                                nbytes -= EXTRACT_SIZE;
-                                spin_unlock_irqrestore(&r->lock, flags);
-                                extract_buf(r, tmp);
-                        }
-
                         spin_lock_irqsave(&r->lock, flags);
                         if (!memcmp(tmp, r->last_data, EXTRACT_SIZE))
                                 panic("Hardware RNG duplicated output!\n");