/*
* Mausezahn - A fast versatile traffic generator
* Copyright (C) 2008-2010 Herbert Haas
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, see http://www.gnu.org/licenses/gpl-2.0.html
*
*/
#include "mz.h"
#include "mops.h"
// Assigns MPLS tag at position i (starting at zero!) with values:
//
// m ... total number of tags (important to set BoS in last tag)
// Label ... label value
// Exp ... EXP field (typically CoS)
// TTL ... Time To Live
//
// NOTE: Two usage possibilities!
//
// 1.) When called from for-loop to add all tags the total size mpls_s
// is updated continuously and the BoS is set in the last tag.
// Therefore set m = total number of tags!
//
// 2.) But when changing a particular tag within an existing MPLS stack
// the total number of tags does not change, therefore use m=0.
//
// RETURN VALUE: 0 upon success, 1 upon failure
//
int mops_mpls(struct mops *mp, int i, int m, u_int32_t Label, u_int8_t Exp, u_int8_t TTL)
{
u_int8_t *ptr;
if ((m) && (i>=m)) return 1; // label index greater than number of labels!
if (Label > 1048575) return 1;
if (Exp > 7) return 1;
// Create binary tag: Label(20) EXP(3) BoS(1) TTL(8)
Label <<= 4;
ptr = (u_int8_t *) &Label;
mp->mpls[4*i+0] = *(ptr+2);
mp->mpls[4*i+1] = *(ptr+1);
mp->mpls[4*i+2] = *(ptr+0);
Exp <<= 1;
mp->mpls[4*i+2] |= Exp;
mp->mpls[4*i+3] = TTL;
if ((m) && (i==(m-1))) // reached last tag!
{
mp->mpls[4*i+2] |= 0x01; // set BoS in last tag
mp->mpls_s =4*m;
mp->use_MPLS = 1;
if ( (mp->eth_type != 0x8847) && (mp->eth_type != 0x8848) )
{
mp->eth_type_backup = mp->eth_type;
}
mp->eth_type = 0x8847;
}
return 0;
}
// Remove MPLS tags from packet mp
//
// j indicates which tag to be removed (1..n)
// j=0 means: remove all tags!
//
// RETURN VALUE: 1 upon failure, 0 upon success
int mops_mpls_remove (struct mops *mp, int j)
{
int a, b, k;
if (j==0) // remove all tags
{
if (mp->use_MPLS)
{
mp->mpls_s=0;
mp->use_MPLS=0;
mp->eth_type = mp->eth_type_backup; // restore original ethertype
return 0;
}
else
return 1;
}
k = mp->mpls_s/4;
if (j>k) return 1; // The packet only consists of k tag(s)
if (k==1) // only delete the single tag
{
mp->mpls_s=0;
mp->use_MPLS=0;
mp->eth_type = mp->eth_type_backup; // restore original ethertype
return 0;
}
// if we got here we have more than one tag:
if (j==k) // remove last tag (of several)
{
mp->mpls_s -=4;
return 0;
}
// remove some non-ending tag: 0, 1, 2, 3
a = (j-1)*4; // target
b = j*4; // source (what should be copied)
memcpy(&mp->mpls[a], &mp->mpls[b], (k-j)*4);
mp->mpls_s -=4;
return 0;
}
// Set BOS in tag k where k=1..n
int mops_mpls_bos (struct mops *mp, int k)
{
int n;
n = mp->mpls_s/4; // n = total number of tags
if (k>n) return 1;
mp->mpls[(k-1)*4+2] |= 0x01;
return 0;
}
// Unset BOS in tag k where k=1..n
int mops_mpls_nobos (struct mops *mp, int k)
{
int n;
n = mp->mpls_s/4; // n = total number of tags
if (k>n) return 1;
mp->mpls[(k-1)*4+2] &= 0xfe;
return 0;
}
value='3' selected='selected'>3
This gets rid of the horrible notion of having that
struct inode *ptmx_inode
be the linchpin of the interface between the pty code and devpts.
By de-emphasizing the ptmx inode, a lot of things actually get cleaner,
and we will have a much saner way forward. In particular, this will
allow us to associate with any particular devpts instance at open-time,
and not be artificially tied to one particular ptmx inode.
The patch itself is actually fairly straightforward, and apart from some
locking and return path cleanups it's pretty mechanical:
- the interfaces that devpts exposes all take "struct pts_fs_info *"
instead of "struct inode *ptmx_inode" now.
NOTE! The "struct pts_fs_info" thing is a completely opaque structure
as far as the pty driver is concerned: it's still declared entirely
internally to devpts. So the pty code can't actually access it in any
way, just pass it as a "cookie" to the devpts code.
- the "look up the pts fs info" is now a single clear operation, that
also does the reference count increment on the pts superblock.
So "devpts_add/del_ref()" is gone, and replaced by a "lookup and get
ref" operation (devpts_get_ref(inode)), along with a "put ref" op
(devpts_put_ref()).
- the pty master "tty->driver_data" field now contains the pts_fs_info,
not the ptmx inode.
- because we don't care about the ptmx inode any more as some kind of
base index, the ref counting can now drop the inode games - it just
gets the ref on the superblock.
- the pts_fs_info now has a back-pointer to the super_block. That's so
that we can easily look up the information we actually need. Although
quite often, the pts fs info was actually all we wanted, and not having
to look it up based on some magical inode makes things more
straightforward.
In particular, now that "devpts_get_ref(inode)" operation should really
be the *only* place we need to look up what devpts instance we're
associated with, and we do it exactly once, at ptmx_open() time.
The other side of this is that one ptmx node could now be associated
with multiple different devpts instances - you could have a single
/dev/ptmx node, and then have multiple mount namespaces with their own
instances of devpts mounted on /dev/pts/. And that's all perfectly sane
in a model where we just look up the pts instance at open time.
This will eventually allow us to get rid of our odd single-vs-multiple
pts instance model, but this patch in itself changes no semantics, only
an internal binding model.
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Jann Horn <jann@thejh.net>
Cc: Greg KH <greg@kroah.com>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>