[PATCH 1/5] hwrng: core - Use struct completion for cleanup_done

Herbert Xu
2014-12-23T05:40:26Z

There is no point in doing a manual completion for cleanup_done
when struct completion fits in perfectly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

drivers/char/hw_random/core.c | 12 +++---------
include/linux/hw_random.h | 3 ++-
2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 6ec4225..3dba2cf 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -60,7 +60,6 @@ static DEFINE_MUTEX(rng_mutex);
static DEFINE_MUTEX(reading_mutex);
static int data_avail;
static u8 *rng_buffer, *rng_fillbuf;
-static DECLARE_WAIT_QUEUE_HEAD(rng_done);
static unsigned short current_quality;
static unsigned short default_quality; /* = 0; default to "off" */

@@ -100,10 +99,7 @@ static inline void cleanup_rng(struct kref *kref)
if (rng->cleanup)
rng->cleanup(rng);

- /* cleanup_done should be updated after cleanup finishes */
- smp_wmb();
- rng->cleanup_done = true;
- wake_up_all(&rng_done);
+ complete(&rng->cleanup_done);
}

static void set_current_rng(struct hwrng *rng)
@@ -498,7 +494,7 @@ int hwrng_register(struct hwrng *rng)
add_early_randomness(rng);
}

- rng->cleanup_done = false;
+ init_completion(&rng->cleanup_done);

out_unlock:
mutex_unlock(&rng_mutex);
@@ -532,9 +528,7 @@ void hwrng_unregister(struct hwrng *rng)
} else
mutex_unlock(&rng_mutex);

- /* Just in case rng is reading right now, wait. */
- wait_event(rng_done, rng->cleanup_done &&
- atomic_read(&rng->ref.refcount) == 0);
+ wait_for_completion(&rng->cleanup_done);
}
EXPORT_SYMBOL_GPL(hwrng_unregister);

diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index 7832e50..eb7b414 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -12,6 +12,7 @@
#ifndef LINUX_HWRANDOM_H_
#define LINUX_HWRANDOM_H_

+#include <linux/completion.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/kref.h>
@@ -46,7 +47,7 @@ struct hwrng {
/* internal. */
struct list_head list;
struct kref ref;
- bool cleanup_done;
+ struct completion cleanup_done;
};

/** Register a new Hardware Random Number Generator driver. */