random: Wake up all getrandom(2) callers when pool is ready

[Herbert Xu]

On Thu, May 21, 2015 at 09:55:17AM +0200, Stephan Mueller wrote:
>
> So, I will create a 2nd wait queue in random.c for uninterruptible waits, 
> change the get_blocking_random_bytes back to void and use wait_event to wait 
> for the initialization.

Hold your horses.  You don't need a second queue, you just need to
change wake_up_interruptible to wake_up.

Hmm, in fact shouldn't this be wake_up_all? Otherwise what are the
other getrandom(2) callers going to do? Ted?

---8<---
If more than one application invokes getrandom(2) before the pool
is ready, then all bar one will be stuck forever because we use
wake_up_interruptible which wakes up a single task.

This patch replaces it with wake_up_all.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 9cd6968..8b8c46b 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -660,7 +660,7 @@ retry:
 		r->entropy_total = 0;
 		if (r == &nonblocking_pool) {
 			prandom_reseed_late();
-			wake_up_interruptible(&urandom_init_wait);
+			wake_up_all(&urandom_init_wait);
 			pr_notice("random: %s pool is initialized\n", r->name);
 		}
 	}

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/