linux-stable.git/net/tipc/link.h, branch linux-4.0.y

tipc: convert legacy nl link stat reset to nl compat

2015-02-09T21:20:48+00:00

Convert TIPC_CMD_RESET_LINK_STATS to compat doit.

Signed-off-by: Richard Alpe 
Reviewed-by: Erik Hugne 
Reviewed-by: Ying Xue 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: convert legacy nl link prop set to nl compat

2015-02-09T21:20:48+00:00

Convert setting of link proprieties to compat doit calls.

Commands converted in this patch:
TIPC_CMD_SET_LINK_TOL
TIPC_CMD_SET_LINK_PRI
TIPC_CMD_SET_LINK_WINDOW

Signed-off-by: Richard Alpe 
Reviewed-by: Erik Hugne 
Reviewed-by: Ying Xue 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: convert legacy nl link stat to nl compat

2015-02-09T21:20:47+00:00

Add functionality for safely appending string data to a TLV without
keeping write count in the caller.

Convert TIPC_CMD_SHOW_LINK_STATS to compat dumpit.

Signed-off-by: Richard Alpe 
Reviewed-by: Erik Hugne 
Reviewed-by: Ying Xue 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: resolve race problem at unicast message reception

2015-02-06T00:00:02+00:00

TIPC handles message cardinality and sequencing at the link layer,
before passing messages upwards to the destination sockets. During the
upcall from link to socket no locks are held. It is therefore possible,
and we see it happen occasionally, that messages arriving in different
threads and delivered in sequence still bypass each other before they
reach the destination socket. This must not happen, since it violates
the sequentiality guarantee.

We solve this by adding a new input buffer queue to the link structure.
Arriving messages are added safely to the tail of that queue by the
link, while the head of the queue is consumed, also safely, by the
receiving socket. Sequentiality is secured per socket by only allowing
buffers to be dequeued inside the socket lock. Since there may be multiple
simultaneous readers of the queue, we use a 'filter' parameter to reduce
the risk that they peek the same buffer from the queue, hence also
reducing the risk of contention on the receiving socket locks.

This solves the sequentiality problem, and seems to cause no measurable
performance degradation.

A nice side effect of this change is that lock handling in the functions
tipc_rcv() and tipc_bcast_rcv() now becomes uniform, something that
will enable future simplifications of those functions.

Reviewed-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: reduce usage of context info in socket and link

2015-02-06T00:00:01+00:00

The most common usage of namespace information is when we fetch the
own node addess from the net structure. This leads to a lot of
passing around of a parameter of type 'struct net *' between
functions just to make them able to obtain this address.

However, in many cases this is unnecessary. The own node address
is readily available as a member of both struct tipc_sock and
tipc_link, and can be fetched from there instead.
The fact that the vast majority of functions in socket.c and link.c
anyway are maintaining a pointer to their respective base structures
makes this option even more compelling.

In this commit, we introduce the inline functions tsk_own_node()
and link_own_node() to make it easy for functions to fetch the node
address from those structs instead of having to pass along and
dereference the namespace struct.

In particular, we make calls to the msg_xx() functions in msg.{h,c}
context independent by directly passing them the own node address
as parameter when needed. Those functions should be regarded as
leaves in the code dependency tree, and it is hence desirable to
keep them namspace unaware.

Apart from a potential positive effect on cache behavior, these
changes make it easier to introduce the changes that will follow
later in this series.

Reviewed-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: avoid stale link after aborted failover

2015-02-05T00:09:31+00:00

During link failover it may happen that the remaining link goes
down while it is still in the process of taking over traffic
from a previously failed link. When this happens, we currently
abort the failover procedure and reset the first failed link to
non-failover mode, so that it will be ready to re-establish
contact with its peer when it comes available.

However, if the first link goes down because its bearer was manually
disabled, it is not enough to reset it; it must also be deleted;
which is supposed to happen when the failover procedure is finished.
Otherwise it will remain a zombie link: attached to the owner node
structure, in mode LINK_STOPPED, and permanently blocking any re-
establishing of the link to the peer via the interface in question.

We fix this by amending the failover abort procedure. Apart from
resetting the link to non-failover state, we test if the link is
also in LINK_STOPPED mode. If so, we delete it, using the conditional
tipc_link_delete() function introduced in the previous commit.

Reviewed-by: Erik Hugne 
Reviewed-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: add reference count to struct tipc_link

2015-02-05T00:09:31+00:00

When a bearer is disabled, all pertaining links will be reset and
deleted. However, if there is a second active link towards a killed
link's destination, the delete has to be postponed until the failover
is finished. During this interval, we currently put the link in zombie
mode, i.e., we take it out of traffic, delete its timer, but leave it
attached to the owner node structure until all missing packets have
been received.  When this is done, we detach the link from its node
and delete it, assuming that the synchronous timer deletion that was
initiated earlier in a different thread has finished.

This is unsafe, as the failover may finish before del_timer_sync()
has returned in the other thread.

We fix this by adding an atomic reference counter of type kref in
struct tipc_link. The counter keeps track of the references kept
to the link by the owner node and the timer. We then do a conditional
delete, based on the reference counter, both after the failover has
been finished and when the timer expires, if applicable. Whoever
comes last, will actually delete the link. This approach also implies
that we can make the deletion of the timer asynchronous.

Reviewed-by: Erik Hugne 
Reviewed-by: Ying Xue 
Signed-off-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: make bearer list support net namespace

2015-01-12T21:24:32+00:00

Bearer list defined as a global variable is used to store bearer
instances. When tipc supports net namespace, bearers created in
one namespace must be isolated with others allocated in other
namespaces, which requires us that the bearer list(bearer_list)
must be moved to tipc_net structure. As a result, a net namespace
pointer has to be passed to functions which access the bearer list.

Signed-off-by: Ying Xue 
Tested-by: Tero Aho 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: make tipc node table aware of net namespace

2015-01-12T21:24:32+00:00

Global variables associated with node table are below:
- node table list (node_htable)
- node hash table list (tipc_node_list)
- node table lock (node_list_lock)
- node number counter (tipc_num_nodes)
- node link number counter (tipc_num_links)

To make node table support namespace, above global variables must be
moved to tipc_net structure in order to keep secret for different
namespaces. As a consequence, these variables are allocated and
initialized when namespace is created, and deallocated when namespace
is destroyed. After the change, functions associated with these
variables have to utilize a namespace pointer to access them. So
adding namespace pointer as a parameter of these functions is the
major change made in the commit.

Signed-off-by: Ying Xue 
Tested-by: Tero Aho 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller

tipc: remove unused tipc_link_get_max_pkt routine

2015-01-12T21:24:32+00:00

Signed-off-by: Ying Xue 
Tested-by: Tero Aho 
Reviewed-by: Jon Maloy 
Signed-off-by: David S. Miller