random32: avoid attempt to late reseed if in the middle of seeding

[~andy/linux] / lib / random32.c

diff --git a/lib/random32.c b/lib/random32.c
index 1e5b2df442916de82ef497f844c068724f8cd555..61489677870007e273301209438ac4913562b140 100644 (file)
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -244,8 +244,19 @@ static void __prandom_reseed(bool late)
        static bool latch = false;
        static DEFINE_SPINLOCK(lock);
 
+       /* Asking for random bytes might result in bytes getting
+        * moved into the nonblocking pool and thus marking it
+        * as initialized. In this case we would double back into
+        * this function and attempt to do a late reseed.
+        * Ignore the pointless attempt to reseed again if we're
+        * already waiting for bytes when the nonblocking pool
+        * got initialized.
+        */
+
        /* only allow initial seeding (late == false) once */
-       spin_lock_irqsave(&lock, flags);
+       if (!spin_trylock_irqsave(&lock, flags))
+               return;
+
        if (latch && !late)
                goto out;
        latch = true;