From: Herbert Xu <herbert@gondor.apana.org.au>
To: Fengguang Wu <fengguang.wu@intel.com>,
Rusty Russell <rusty@rustcorp.com.au>, LKP <lkp@01.org>,
linux-kernel@vger.kernel.org,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Amos Kong <akong@redhat.com>,
m@bues.ch, mpm@selenic.com, amit.shah@redhat.com
Subject: [PATCH 3/5] hwrng: core - Do not register device opportunistically
Date: Tue, 23 Dec 2014 16:40:19 +1100 [thread overview]
Message-ID: <E1Y3ICh-0007d7-SM@gondolin.me.apana.org.au> (raw)
In-Reply-To: 20141223053909.GA28001@gondor.apana.org.au
Currently we only register the device when a valid RNG is added.
However the way it's done is buggy because we test whether there
is a current RNG to determine whether we need to register. As
the current RNG may be missing due to a reinitialisation error
this can lead to a reregistration of the device.
As the device already has to handle a NULL current RNG anyway,
let's just register the device always and remove the complexity.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
drivers/char/hw_random/core.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 42827fd..1d342f0 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -372,14 +372,14 @@ static DEVICE_ATTR(rng_available, S_IRUGO,
NULL);
-static void unregister_miscdev(void)
+static void __exit unregister_miscdev(void)
{
device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
misc_deregister(&rng_miscdev);
}
-static int register_miscdev(void)
+static int __init register_miscdev(void)
{
int err;
@@ -484,12 +484,6 @@ int hwrng_register(struct hwrng *rng)
if (err)
goto out_unlock;
set_current_rng(rng);
-
- err = register_miscdev();
- if (err) {
- drop_current_rng();
- goto out_unlock;
- }
}
list_add_tail(&rng->list, &rng_list);
@@ -530,7 +524,6 @@ void hwrng_unregister(struct hwrng *rng)
if (list_empty(&rng_list)) {
mutex_unlock(&rng_mutex);
- unregister_miscdev();
if (hwrng_fill)
kthread_stop(hwrng_fill);
} else
@@ -540,16 +533,24 @@ void hwrng_unregister(struct hwrng *rng)
}
EXPORT_SYMBOL_GPL(hwrng_unregister);
-static void __exit hwrng_exit(void)
+static int __init hwrng_modinit(void)
+{
+ return register_miscdev();
+}
+
+static void __exit hwrng_modexit(void)
{
mutex_lock(&rng_mutex);
BUG_ON(current_rng);
kfree(rng_buffer);
kfree(rng_fillbuf);
mutex_unlock(&rng_mutex);
+
+ unregister_miscdev();
}
-module_exit(hwrng_exit);
+module_init(hwrng_modinit);
+module_exit(hwrng_modexit);
MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
MODULE_LICENSE("GPL");
next prev parent reply other threads:[~2014-12-23 5:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-23 3:09 [hwrng] WARNING: CPU: 0 PID: 1 at include/linux/kref.h:47 set_current_rng() Fengguang Wu
2014-12-23 5:39 ` [0/5] hwrng: Fix kref warning and underlying bugs Herbert Xu
2014-12-23 5:40 ` [PATCH 1/5] hwrng: core - Use struct completion for cleanup_done Herbert Xu
2014-12-23 23:19 ` Rusty Russell
2014-12-23 5:40 ` [PATCH 2/5] hwrng: core - Fix current_rng init/cleanup race yet again Herbert Xu
2014-12-23 23:26 ` Rusty Russell
2014-12-26 0:52 ` Herbert Xu
2014-12-23 5:40 ` Herbert Xu [this message]
2014-12-23 23:29 ` [PATCH 3/5] hwrng: core - Do not register device opportunistically Rusty Russell
2014-12-26 1:00 ` Herbert Xu
2014-12-23 5:40 ` [PATCH 4/5] hwrng: core - Drop current rng in set_current_rng Herbert Xu
2014-12-23 5:40 ` [PATCH 5/5] hwrng: core - Move hwrng_init call into set_current_rng Herbert Xu
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