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Message-ID: <1416413891-29562-3-git-send-email-mst@redhat.com>
Date: Wed, 19 Nov 2014 18:18:36 +0200
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: rusty@...tcorp.com.au, davem@...emloft.net,
Jason Wang <jasowang@...hat.com>,
Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>,
Ben Hutchings <ben@...adent.org.uk>,
Tom Herbert <therbert@...gle.com>,
Masatake YAMATO <yamato@...hat.com>, Xi Wang <xii@...gle.com>,
netdev@...r.kernel.org
Subject: [PATCH 2/3] tun: reuse IFF_ flags internally
By reusing IFF_ flags for internal tun device flags,
we can get rid of a bunch of code translating back
and forth.
This cleanup exposes a bug: TUNGETFEATURES reports IFF_TUN and IFF_TAP
which aren't legal for TUNSETFEATURES (but, correctly, doesn't report
IFF_PERSIST which also isn't legal there).
I'm not fixing this bug at the moment, just in case some weird
userspace depends on it, using TUNGETFEATURES to check device type.
Follow-up patches will get rid of some of TUN_ macros,
using IFF_ directly instead.
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
drivers/net/tun.c | 83 +++++++++++++++----------------------------------------
1 file changed, 22 insertions(+), 61 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 81735f5..e4bd542 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -104,19 +104,23 @@ do { \
#endif
/* TUN device flags */
-#define TUN_TUN_DEV 0x0001
-#define TUN_TAP_DEV 0x0002
-#define TUN_TYPE_MASK 0x000f
+#define TUN_TUN_DEV IFF_TUN
+#define TUN_TAP_DEV IFF_TAP
+#define TUN_TYPE_MASK (IFF_TUN | IFF_TAP)
-#define TUN_FASYNC 0x0010
-#define TUN_NOCHECKSUM 0x0020
-#define TUN_NO_PI 0x0040
+/* IFF_ATTACH_QUEUE is never stored in device flags,
+ * overload it to mean fasync when stored there.
+ */
+#define TUN_FASYNC IFF_ATTACH_QUEUE
+#define TUN_NO_PI IFF_NO_PI
/* This flag has no real effect */
-#define TUN_ONE_QUEUE 0x0080
-#define TUN_PERSIST 0x0100
-#define TUN_VNET_HDR 0x0200
-#define TUN_TAP_MQ 0x0400
+#define TUN_ONE_QUEUE IFF_ONE_QUEUE
+#define TUN_PERSIST IFF_PERSIST
+#define TUN_VNET_HDR IFF_VNET_HDR
+#define TUN_TAP_MQ IFF_MULTI_QUEUE
+#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
+ IFF_MULTI_QUEUE)
#define GOODCOPY_LEN 128
#define FLT_EXACT_COUNT 8
@@ -1529,32 +1533,7 @@ static struct proto tun_proto = {
static int tun_flags(struct tun_struct *tun)
{
- int flags = 0;
-
- if (tun->flags & TUN_TUN_DEV)
- flags |= IFF_TUN;
- else
- flags |= IFF_TAP;
-
- if (tun->flags & TUN_NO_PI)
- flags |= IFF_NO_PI;
-
- /* This flag has no real effect. We track the value for backwards
- * compatibility.
- */
- if (tun->flags & TUN_ONE_QUEUE)
- flags |= IFF_ONE_QUEUE;
-
- if (tun->flags & TUN_VNET_HDR)
- flags |= IFF_VNET_HDR;
-
- if (tun->flags & TUN_TAP_MQ)
- flags |= IFF_MULTI_QUEUE;
-
- if (tun->flags & TUN_PERSIST)
- flags |= IFF_PERSIST;
-
- return flags;
+ return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN | IFF_TAP);
}
static ssize_t tun_show_flags(struct device *dev, struct device_attribute *attr,
@@ -1714,28 +1693,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun_debug(KERN_INFO, tun, "tun_set_iff\n");
- if (ifr->ifr_flags & IFF_NO_PI)
- tun->flags |= TUN_NO_PI;
- else
- tun->flags &= ~TUN_NO_PI;
-
- /* This flag has no real effect. We track the value for backwards
- * compatibility.
- */
- if (ifr->ifr_flags & IFF_ONE_QUEUE)
- tun->flags |= TUN_ONE_QUEUE;
- else
- tun->flags &= ~TUN_ONE_QUEUE;
-
- if (ifr->ifr_flags & IFF_VNET_HDR)
- tun->flags |= TUN_VNET_HDR;
- else
- tun->flags &= ~TUN_VNET_HDR;
-
- if (ifr->ifr_flags & IFF_MULTI_QUEUE)
- tun->flags |= TUN_TAP_MQ;
- else
- tun->flags &= ~TUN_TAP_MQ;
+ tun->flags = (tun->flags & ~TUN_FEATURES) |
+ (ifr->ifr_flags & TUN_FEATURES);
/* Make sure persistent devices do not get stuck in
* xoff state.
@@ -1898,9 +1857,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
if (cmd == TUNGETFEATURES) {
/* Currently this just means: "what IFF flags are valid?".
* This is needed because we never checked for invalid flags on
- * TUNSETIFF. */
- return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
- IFF_VNET_HDR | IFF_MULTI_QUEUE,
+ * TUNSETIFF. Why do we report IFF_TUN and IFF_TAP which are
+ * not legal for TUNSETIFF here? It's probably a bug, but it
+ * doesn't seem to be worth fixing.
+ */
+ return put_user(IFF_TUN | IFF_TAP | TUN_FEATURES,
(unsigned int __user*)argp);
} else if (cmd == TUNSETQUEUE)
return tun_set_queue(file, &ifr);
--
MST
--
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