After launching mesh discovery in tx path, reference count was not being
decremented. This was preventing module unload.
Signed-off-by: Brian Cavagnolo <brian@cozybit.com>
Signed-off-by: Andrey Yurovsky <andrey@cozybit.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Caused by call to request_module() while holding nf_conntrack_lock.
Reported-and-tested-by: Kövesdi György <kgy@teledigit.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The previous fix to paged packets broke the merging because it
reset the skb->len before we added it to the merged packet. This
wasn't detected because it simply resulted in the truncation of
the packet while the missing bit is subsequently retransmitted.
The fix is to store skb->len before we clobber it.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a frag is shorter than an Ethernet header, we'd return a
zeroed packet instead of aborting. This patch fixes that.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
We need to perform skb_postpull_rcsum after pulling the IPv6
header in order to maintain the correctness of the complete
checksum.
This patch also adds a missing iph reload after pulling.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
register_pernet_gen_subsys omits mutex_unlock in one fail path.
Fix it.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit fc8c7dc1b2.
As indicated by Jiri Klimes, this won't work. These numbers are
not only used the size validation, they are also used to locate
attributes sitting after the message.
Signed-off-by: David S. Miller <davem@davemloft.net>
The trick in socket splicing where we try to convert the skb->data
into a page based reference using virt_to_page() does not work so
well.
The idea is to pass the virt_to_page() reference via the pipe
buffer, and refcount the buffer using a SKB reference.
But if we are splicing from a socket to a socket (via sendpage)
this doesn't work.
The from side processing will grab the page (and SKB) references.
The sendpage() calls will grab page references only, return, and
then the from side processing completes and drops the SKB ref.
The page based reference to skb->data is not enough to keep the
kmalloc() buffer backing it from being reused. Yet, that is
all that the socket send side has at this point.
This leads to data corruption if the skb->data buffer is reused
by SLAB before the send side socket actually gets the TX packet
out to the device.
The fix employed here is to simply allocate a page and copy the
skb->data bytes into that page.
This will hurt performance, but there is no clear way to fix this
properly without a copy at the present time, and it is important
to get rid of the data corruption.
With fixes from Herbert Xu.
Tested-by: Willy Tarreau <w@1wt.eu>
Foreseen-by: Changli Gao <xiaosuo@gmail.com>
Diagnosed-by: Willy Tarreau <w@1wt.eu>
Reported-by: Willy Tarreau <w@1wt.eu>
Fixed-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
I'm trying to track down why people're hitting the checksum warning
in skb_gso_segment. As the problem seems to be hitting lots of
people and I can't reproduce it or locate the bug, here is a patch
to print out more details which hopefully should help us to track
this down.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
The country IE number of channels on 5 GHz specifies the number
of 5 GHz channels, not the number of sequential channel numbers.
For example, if in a country IEs if the first channel given is 36
and the number of channels passed is 4 then the individual channel
numbers defined for the 5 GHz PHY by these parameters
are: 36, 40, 44, 48
not: 36, 37, 38, 39
See: http://tinyurl.com/11d-clarification
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This fixes a regression on disallowing bands introduced with the new
802.11d support. The issue is that IEEE-802.11 allows APs to send
a subset of what a country regulatory domain defines. This was clarified
in this document:
http://tinyurl.com/11d-clarification
As such it is possible, and this is what is done in practice, that a
single band 2.4 GHz AP will only send 2.4 GHz band regulatory information
through the 802.11 country information element and then the current
intersection with what CRDA provided yields a regulatory domain with
no 5 GHz information -- even though that country may actually allow
5 GHz operation. We correct this by only applying the intersection rules
on a channel if the the intersection yields a regulatory rule on the
same band the channel is on.
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This allows us to make more wiphy specific judgements when
handling the channels later on.
Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Fix (delete) more mac80211 kernel-doc:
Warning(linux-2.6.28-git13//include/net/mac80211.h:375): Excess struct/union/enum/typedef member 'retry_count' description in 'ieee80211_tx_info'
Warning(linux-2.6.28-git13//net/mac80211/sta_info.h:308): Excess struct/union/enum/typedef member 'last_txrate' description in 'sta_info'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (95 commits)
b44: GFP_DMA skb should not escape from driver
korina: do not use IRQF_SHARED with IRQF_DISABLED
korina: do not stop queue here
korina: fix handling tx_chain_tail
korina: do tx at the right position
korina: do schedule napi after testing for it
korina: rework korina_rx() for use with napi
korina: disable napi on close and restart
korina: reset resource buffer size to 1536
korina: fix usage of driver_data
bnx2x: First slow path interrupt race
bnx2x: MTU Filter
bnx2x: Indirection table initialization index
bnx2x: Missing brackets
bnx2x: Fixing the doorbell size
bnx2x: Endianness issues
bnx2x: VLAN tagged packets without VLAN offload
bnx2x: Protecting the link change indication
bnx2x: Flow control updated before reporting the link
bnx2x: Missing mask when calculating flow control
...
If INET=y and INFINIBAND=y, but IPV6=m then INFINIBAND_ADDR_TRANS is set
to n and the RDMA CM functions rdma_connect() et al are not built.
However, the current config dependencies allow NET_9P_RDMA to be selected
in this, which leads to a build failure. Fix this by adding a dependency
on INFINIBAND_ADDR_TRANS to disallow NET_9P_RDMA in this case.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Due to the loopback functionality in can_send() we can not invoke it
from hardirq context which was done inside the
bcm_tx_timeout_handler() hrtimer callback:
[ 700.361154] [<c012228c>] warn_slowpath+0x80/0xb6
[ 700.361163] [<c013d559>] valid_state+0x125/0x136
[ 700.361171] [<c013d858>] mark_lock+0x18e/0x332
[ 700.361180] [<c013e300>] __lock_acquire+0x12e/0xb1e
[ 700.361189] [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[ 700.361198] [<c031e20a>] dev_queue_xmit+0x191/0x479
[ 700.361206] [<c01262a7>] __local_bh_disable+0x2b/0x64
[ 700.361213] [<c031e20a>] dev_queue_xmit+0x191/0x479
[ 700.361225] [<f8aa69a1>] can_send+0xd7/0x11a [can]
[ 700.361235] [<f8ab522b>] bcm_can_tx+0x9d/0xd9 [can_bcm]
[ 700.361245] [<f8ab597f>] bcm_tx_timeout_handler+0x6a/0xbc [can_bcm]
[ 700.361255] [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[ 700.361263] [<c0134143>] __run_hrtimer+0x5a/0x86
[ 700.361273] [<f8ab5915>] bcm_tx_timeout_handler+0x0/0xbc [can_bcm]
[ 700.361282] [<c0134a50>] hrtimer_interrupt+0xb9/0x110
This patch moves the rest of the functionality from the hrtimer
callback to the already existing tasklet to fix this slowpath problem.
Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This adds an init_dummy_netdev() function that gets a network device
structure (allocation and lifetime entirely under caller's control) and
initialize the minimum amount of fields so it can be used to schedule
NAPI polls without registering a full blown interface. This is to be
used by drivers that need to tie several hardware interfaces to a single
NAPI poll scheduler due to HW limitations.
It also updates the ibm_newemac driver to use that, this fixing the
oops on 2.6.29 due to passing NULL as "dev" to netif_napi_add()
Symbol is exported GPL only a I don't think we want binary drivers doing
that sort of acrobatics (if we want them at all).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Tested-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When we get a GSO packet from an untrusted source, we need to
ensure that it is sufficiently long so that we don't end up
crashing.
Based on discovery and patch by Ian Campbell.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When an skb with page frags is merged into an existing one, we
cannibalise its reference count. This is OK when the skb is
reused because we set nr_frags to zero in that case. However,
for the case where the skb is freed through kfree_skb, we didn't
clear nr_frags which causes the page to be freed prematurely.
This is fixed by moving the skb resetting into skb_gro_receive.
Reported-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
As GRO cannot be applied to packets with frag_list we need to
make sure that we reject such packets if they are fed to us,
e.g., through a tunnel device.
Also there is no point in applying GRO on GSO packets so they
too should be rejected. This allows GRO to be used in virtio-net
which may produce GSO packets directly but may still benefit
from GRO if the other end of it doesn't support GSO.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
When a fib6 table dump is prematurely ended, we won't unlink
its walker from the list. This causes all sorts of grief for
other users of the list later.
Reported-by: Chris Caputo <ccaputo@alt.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
As spotted by Willy Tarreau, current splice() from tcp socket to pipe is not
optimal. It processes at most one segment per call.
This results in low performance and very high overhead due to syscall rate
when splicing from interfaces which do not support LRO.
Willy provided a patch inside tcp_splice_read(), but a better fix
is to let tcp_read_sock() process as many segments as possible, so
that tcp_rcv_space_adjust() and tcp_cleanup_rbuf() are called less
often.
With this change, splice() behaves like tcp_recvmsg(), being able
to consume many skbs in one system call. With typical 1460 bytes
of payload per frame, that means splice(SPLICE_F_NONBLOCK) can return
16*1460 = 23360 bytes.
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/mac80211/ht.c: In function ‘ieee80211_start_tx_ba_session’:
net/mac80211/ht.c:472: warning: ‘ret’ may be used uninitialized in this function
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Currently htb_do_events() breaks events recounting for a level after 2
jiffies, but there is no reason to repeat this for next levels and
increase delays even more (with softirqs disabled). htb_dequeue_tree()
can add to this too, btw. In such a case q->now time is invalid anyway.
Thanks to Patrick McHardy for spotting an error around earlier version
of this patch.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Next event time should consider jiffies used for recounting. Otherwise
qdisc_watchdog_schedule() triggers hrtimer immediately with the event
in the past, and may cause very high ksoftirqd cpu usage (if highres
is on).
There is also removed checking "event" for zero in htb_dequeue(): it's
always true in this place.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
netfilter: xt_time: print timezone for user information
Let users have a way to figure out if their distro set the kernel
timezone at all.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
nf_conntrack_alloc cannot return NULL, so there is no need to check for
NULL before using the value. I have also removed the initialization of ct
to NULL in nf_conntrack_alloc, since the value is never used, and since
perhaps it might lead one to think that return ct at the end might return
NULL.
The semantic patch that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@match exists@
expression x, E;
position p1,p2;
statement S1, S2;
@@
x@p1 = nf_conntrack_alloc(...)
... when != x = E
(
if (x@p2 == NULL || ...) S1 else S2
|
if (x@p2 == NULL && ...) S1 else S2
)
@other_match exists@
expression match.x, E1, E2;
position p1!=match.p1,match.p2;
@@
x@p1 = E1
... when != x = E2
x@p2
@ script:python depends on !other_match@
p1 << match.p1;
p2 << match.p2;
@@
print "%s: call to nf_conntrack_alloc %s bad test %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
An old bug crept back into the ICMP/ICMPv6 conntrack protocols: the timeout
values are defined as unsigned longs, the sysctl's maxsize is set to
sizeof(unsigned int). Use unsigned int for the timeout values as in the
other conntrack protocols.
Reported-by: Jean-Mickael Guerin <jean-mickael.guerin@6wind.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 8cc784ee (netfilter: change return types of match functions
for ebtables extensions) broke ebtables matches by inverting the
sense of match/nomatch.
Reported-by: Matt Cross <matthltc@us.ibm.com>
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 55b69e91 (netfilter: implement NFPROTO_UNSPEC as a wildcard
for extensions) broke revision probing for matches and targets that
are registered with NFPROTO_UNSPEC.
Fix by continuing the search on the NFPROTO_UNSPEC list if nothing
is found on the af-specific lists.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
The PPPOE/VLAN processing code in the bridge netfilter is broken
by design. The VLAN tag and the PPPOE session ID are an integral
part of the packet flow information, yet they're completely
ignored by the bridge netfilter. This is potentially a security
hole as it treats all VLANs and PPPOE sessions as the same.
What's more, it's actually broken for PPPOE as the bridge netfilter
tries to trim the packets to the IP length without adjusting the
PPPOE header (and adjusting the PPPOE header isn't much better
since the PPPOE peer may require the padding to be present).
Therefore we should disable this by default.
It does mean that people relying on this feature may lose networking
depending on how their bridge netfilter rules are configured.
However, IMHO the problems this code causes are serious enough to
warrant this.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently the bridge FORWARD/POST_ROUTING chains treats all
non-IPv4 packets as IPv6. This packet fixes that by returning
NF_ACCEPT on non-IP packets instead, just as is done in PRE_ROUTING.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Don't spam logs for locally generated short packets. these can only
be generated by root.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes a panic that might occur, if the device is part of a mesh
and tries to send with a higher rate index than "0".
kernel BUG at net/mac80211/rate.c:239!
invalid opcode: 0000 [#1] SMP
[...]
Call Trace:
<IRQ> <0> ? invoke_tx_handlers+0x474/0xb57 [mac80211]
? __ieee80211_tx_prepare+0x260/0x2a8 [mac80211]
? ieee80211_master_start_xmit+0x300/0x43a [mac80211]
? __qdisc_run+0xde/0x1da
? net_tx_action+0xb4/0x102
Kernel panic - not syncing: Fatal exception in interrupt
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Changing mode on an interface is not allowed if IBSS is disabled for the
current channel. That restriction should only apply when switching to
the ad-hoc mode, as it was prior to "cfg80211: handle SIOCGIWMODE/SIOCSIWMODE".
Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This patch fixes the following WARNING (caused by rix_to_ndx): "
>WARNING: at net/mac80211/rc80211_minstrel.c:69 minstrel_rate_init+0xd2/0x33a [mac80211]()
>[...]
>Call Trace:
> warn_on_slowpath+0x51/0x75
> _format_mac_addr+0x4c/0x88
> minstrel_rate_init+0xd2/0x33a [mac80211]
> print_mac+0x16/0x1b
> schedule_hrtimeout_range+0xdc/0x107
> ieee80211_add_station+0x158/0x1bd [mac80211]
> nl80211_new_station+0x1b3/0x20b [cfg80211]
The reason is that I'm experimenting with "g" only mode on a 802.11 b/g card.
Therefore rate_lowest_index returns 4 (= 6Mbit, instead of usual 0 = 1Mbit).
Since mi->r array is initialized with zeros in minstrel_alloc_sta,
rix_to_ndx has a hard time to find the 6Mbit entry and will trigged the WARNING.
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Acked-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The recent dmaengine rework removed the capability to remove dma device
driver modules while net_dma is active. Rather than notify
dmaengine-clients that channels are trying to be removed, we now rely on
clients to notify dmaengine when they no longer have a need for
channels. Teach net_dma to release channels by taking dmaengine
references at netdevice open and dropping references at netdevice close.
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Thanks to Wei and Arnaldo for pointing out the correct
new reference for CCID-3.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Removed the __exit annotation of tfrc_lib_exit(), in order to suppress the following section mismatch messages:
WARNING: net/dccp/dccp.o(.text+0xd9): Section mismatch in reference from the function ccid_cleanup_builtins() to the function .exit.text:tfrc_lib_exit()
The function ccid_cleanup_builtins() references a function in an exit section.
Often the function tfrc_lib_exit() has valid usage outside the exit section
and the fix is to remove the __exit annotation of tfrc_lib_exit.
WARNING: net/dccp/dccp.o(.init.text+0x48): Section mismatch in reference from the function ccid_initialize_builtins() to the function .exit.text:tfrc_lib_exit()
The function __init ccid_initialize_builtins() references
a function __exit tfrc_lib_exit().
This is often seen when error handling in the init function
uses functionality in the exit path.
The fix is often to remove the __exit annotation of
tfrc_lib_exit() so it may be used outside an exit section.
Signed-off-by: Leonardo Potenza <lpotenza@inwind.it>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
In each case, if the NULL test is necessary, then the dereference should be
moved below the NULL test.
The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@
- T i = E->fld;
+ T i;
... when != E
when != i
if (E == NULL) S
+ i = E->fld;
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
ARRAY_SIZE is more concise to use when the size of an array is divided by
the size of its type or the size of its first element.
The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@i@
@@
#include <linux/kernel.h>
@depends on i using "paren.iso"@
type T;
T[] E;
@@
- (sizeof(E)/sizeof(T))
+ ARRAY_SIZE(E)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When I made ipcomp use frags, I forgot to take out the original
truesize update that was added for pskb_expand_head. As we no
longer expand the head of skb, that update should have been removed.
This bug is not related to the truesize warnings since we only
made it bigger than what it should've been.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/djbw/async_tx: (22 commits)
ioat: fix self test for multi-channel case
dmaengine: bump initcall level to arch_initcall
dmaengine: advertise all channels on a device to dma_filter_fn
dmaengine: use idr for registering dma device numbers
dmaengine: add a release for dma class devices and dependent infrastructure
ioat: do not perform removal actions at shutdown
iop-adma: enable module removal
iop-adma: kill debug BUG_ON
iop-adma: let devm do its job, don't duplicate free
dmaengine: kill enum dma_state_client
dmaengine: remove 'bigref' infrastructure
dmaengine: kill struct dma_client and supporting infrastructure
dmaengine: replace dma_async_client_register with dmaengine_get
atmel-mci: convert to dma_request_channel and down-level dma_slave
dmatest: convert to dma_request_channel
dmaengine: introduce dma_request_channel and private channels
net_dma: convert to dma_find_channel
dmaengine: provide a common 'issue_pending_all' implementation
dmaengine: centralize channel allocation, introduce dma_find_channel
dmaengine: up-level reference counting to the module level
...
