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The ELP worker needs to calculate new metric values for all neighbors
"reachable" over an interface. Some of the used metric sources require
locks which might need to sleep. This sleep is incompatible with the RCU
list iterator used for the recorded neighbors. The initial approach to work
around of this problem was to queue another work item per neighbor and then
run this in a new context.
Even when this solved the RCU vs might_sleep() conflict, it has a major
problems: Nothing was stopping the work item in case it is not needed
anymore - for example because one of the related interfaces was removed or
the batman-adv module was unloaded - resulting in potential invalid memory
accesses.
Directly canceling the metric worker also has various problems:
* cancel_work_sync for a to-be-deactivated interface is called with
rtnl_lock held. But the code in the ELP metric worker also tries to use
rtnl_lock() - which will never return in this case. This also means that
cancel_work_sync would never return because it is waiting for the worker
to finish.
* iterating over the neighbor list for the to-be-deactivated interface is
currently done using the RCU specific methods. Which means that it is
possible to miss items when iterating over it without the associated
spinlock - a behaviour which is acceptable for a periodic metric check
but not for a cleanup routine (which must "stop" all still running
workers)
The better approch is to get rid of the per interface neighbor metric
worker and handle everything in the interface worker. The original problems
are solved by:
* creating a list of neighbors which require new metric information inside
the RCU protected context, gathering the metric according to the new list
outside the RCU protected context
* only use rcu_trylock inside metric gathering code to avoid a deadlock
when the cancel_delayed_work_sync is called in the interface removal code
(which is called with the rtnl_lock held)
Cc: stable@vger.kernel.org
Fixes: c833484e5f38 ("batman-adv: ELP - compute the metric based on the estimated throughput")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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The batman-adv source code was using the year of publication (to net-next)
as "last" year for the copyright statement. The whole source code mentioned
in the MAINTAINERS "BATMAN ADVANCED" section was handled as a single entity
regarding the publishing year.
This avoided having outdated (in sense of year information - not copyright
holder) publishing information inside several files. But since the simple
"update copyright year" commit (without other changes) in the file was not
well received in the upstream kernel, the option to not have a copyright
year (for initial and last publication) in the files are chosen instead.
More detailed information about the years can still be retrieved from the
SCM system.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Acked-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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While it can be slightly beneficial for the build performance to use
forward declarations instead of includes, the handling of them together
with changes in the included headers makes it unnecessary complicated and
fragile. Just replace them with actual includes since some parts (hwmon,
..) of the kernel even request avoidance of forward declarations and net/
is mostly not using them in *.c file.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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All files got a SPDX-License-Identifier with commit 7db7d9f369a4
("batman-adv: Add SPDX license identifier above copyright header"). All the
required information about the license conditions can be found in
LICENSES/.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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The "Linux kernel licensing rules" require that each file has a SPDX
license identifier as first line (and sometimes as second line).
The FSFE REUSE practices [1] would also require the same tags but have no
restrictions on the placement in the source file. Using the "Linux kernel
licensing rules" is therefore also fulfilling the FSFE REUSE practices
requirements at the same time.
[1] https://reuse.software/practices/
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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It is easier to detect if a include is already there for a used
functionality when the includes are ordered. Using an alphabetic order
together with the grouping in commit 1e2c2a4fe4a5 ("batman-adv: Add
required includes to all files") makes includes better manageable.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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This fix prevents nodes to wrongly create a 00:00:00:00:00:00 originator
which can potentially interfere with the rest of the neighbor statistics.
Fixes: d6f94d91f766 ("batman-adv: ELP - adding basic infrastructure")
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
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In case of wireless interface retrieve the throughput by
querying cfg80211. To perform this call a separate work
must be scheduled because the function may sleep and this
is not allowed within an RCU protected context (RCU in this
case is used to iterate over all the neighbours).
Use ethtool to retrieve information about an Ethernet link
like HALF/FULL_DUPLEX and advertised bandwidth (e.g.
100/10Mbps).
The metric is updated each time a new ELP packet is sent,
this way it is possible to timely react to a metric
variation which can imply (for example) a neighbour
disconnection.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
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Initially developed by Linus during a 6 months trainee study
period in Ascom (Switzerland) AG.
Signed-off-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
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The B.A.T.M.A.N. protocol originally only used a single
message type (called OGM) to determine the link qualities to
the direct neighbors and spreading these link quality
information through the whole mesh. This procedure is
summarized on the BATMAN concept page and explained in
details in the RFC draft published in 2008.
This approach was chosen for its simplicity during the
protocol design phase and the implementation. However, it
also bears some drawbacks:
* Wireless interfaces usually come with some packet loss,
therefore a higher broadcast rate is desirable to allow
a fast reaction on flaky connections.
Other interfaces of the same host might be connected to
Ethernet LANs / VPNs / etc which rarely exhibit packet
loss would benefit from a lower broadcast rate to reduce
overhead.
* It generally is more desirable to detect local link
quality changes at a faster rate than propagating all
these changes through the entire mesh (the far end of
the mesh does not need to care about local link quality
changes that much). Other optimizations strategies, like
reducing overhead, might be possible if OGMs weren't
used for all tasks in the mesh at the same time.
As a result detecting local link qualities shall be handled
by an independent message type, ELP, whereas the OGM message
type remains responsible for flooding the mesh with these
link quality information and determining the overall path
transmit qualities.
Developed by Linus during a 6 months trainee study period in
Ascom (Switzerland) AG.
Signed-off-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
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