Linux cryptographic layer development

* [PATCH] hwrng: core - Allocate memory during module init
From: PrasannaKumar Muralidharan @ 2016-09-04  8:29 UTC (permalink / raw)
  To: mpm, herbert, jslaby, peter, lee.jones, linux-crypto; +Cc: prasannatsmkumar

In core rng_buffer and rng_fillbuf is allocated in hwrng_register only
once and it is freed during module exit. This patch moves allocating
rng_buffer and rng_fillbuf from hwrng_register to rng core's init. This
avoids checking whether rng_buffer and rng_fillbuf was allocated from
every hwrng_register call. Also moving them to module init makes it
explicit that it is freed in module exit.

Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
---
 drivers/char/hw_random/core.c | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 9203f2d..ec6846b 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -449,22 +449,6 @@ int hwrng_register(struct hwrng *rng)
 		goto out;
 
 	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;
-	}
-	if (!rng_fillbuf) {
-		rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL);
-		if (!rng_fillbuf) {
-			kfree(rng_buffer);
-			goto out_unlock;
-		}
-	}
-
 	/* Must not register two RNGs with the same name. */
 	err = -EEXIST;
 	list_for_each_entry(tmp, &rng_list, list) {
@@ -573,6 +557,17 @@ EXPORT_SYMBOL_GPL(devm_hwrng_unregister);
 
 static int __init hwrng_modinit(void)
 {
+	/* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
+	rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
+	if (!rng_buffer)
+		return -ENOMEM;
+
+	rng_fillbuf = kmalloc(rng_buffer_size(), GFP_KERNEL);
+	if (!rng_fillbuf) {
+		kfree(rng_buffer);
+		return -ENOMEM;
+	}
+
 	return register_miscdev();
 }
 
-- 
2.5.0

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