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tun: Report "persist" flag to userspace

PATCH Applied Pavel Emelyanov 2 participants 2 messages Jun 11, 2013 – Jun 12, 2013

Subsystems (3)
Networking Network drivers TUN/TAP driver
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Pavel Emelyanov

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#0 lore raw

PATCH 1/1 tun: Report "persist" flag to userspace

The TUN_PERSIST flag is not reported at all -- both TUNGETIFF, and sysfs "flags" attribute skip one. Knowing whether a device is persistent or not is critical for checkpoint-restore, thus I propose to add the read-only IFF_PERSIST one for this.

Setting this new IFF_PERSIST is hardly possible, as TUNSETIFF doesn't check for unknown flags being zero and thus there can be trash.

Signed-off-by Pavel Emelyanov <[email protected]>

---

drivers/net/tun.c +3 -0
index 89776c5..b90a731 100644
@@ -1530,6 +1530,9 @@ static int tun_flags(struct tun_struct *tun)
 	if (tun->flags & TUN_TAP_MQ)
 		flags |= IFF_MULTI_QUEUE;
 
+	if (tun->flags & TUN_PERSIST)
+		flags |= IFF_PERSIST;
+
 	return flags;
 }
include/uapi/linux/if_tun.h +2 -0
index 2835b85..82334f8 100644
@@ -68,6 +68,8 @@
 #define IFF_MULTI_QUEUE 0x0100
 #define IFF_ATTACH_QUEUE 0x0200
 #define IFF_DETACH_QUEUE 0x0400
+/* read-only flag */
+#define IFF_PERSIST	0x0800
 
 /* Features for GSO (TUNSETOFFLOAD). */
 #define TUN_F_CSUM	0x01	/* You can hand me unchecksummed packets. */
maintainer Applied
#1 lore raw

From: Pavel Emelyanov <[email protected]>
Date: Tue, 11 Jun 2013 14:41:24 +0400

Quoted 9 lines

The TUN_PERSIST flag is not reported at all -- both TUNGETIFF, and sysfs "flags" attribute skip one. Knowing whether a device is persistent or not is critical for checkpoint-restore, thus I propose to add the read-only IFF_PERSIST one for this.

Setting this new IFF_PERSIST is hardly possible, as TUNSETIFF doesn't check for unknown flags being zero and thus there can be trash.

Signed-off-by Pavel Emelyanov <[email protected]>

Applied, thanks.