VLAN filtering is broken, due to reading the incorrect register for
the VLAN filtering settings. Fixed by reading/writing the correct
register.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
so update things accordingly
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
The association request includes a list of supported data rates.
802.11b: 4 supported rates.
802.11g: 12 (8 + 4) supported rates.
802.11a: 8 supported rates.
The rates tag of the assoc request has room for only 8 rates. In case of
802.11g an extended rate tag is appended. However in net/wireless/mlme.c
an extended (empty) rate tag is also appended if the number of rates is
exact 8. This empty (length=0) extended rates tag causes some APs to
deny association with code 18 (unsupported rates). These APs include my
ZyXEL G-570U, and according to Tomas Winkler som Cisco APs.
'If count == 8' has been used to check for the need for an extended rates
tag. But count would also be equal to 8 if the for loop exited because of
no more supported rates. Therefore a check for count being less than
rates_len would seem more correct.
Thanks to:
* Dan Williams for newbie guidance
* Tomas Winkler for confirming the problem
Signed-off-by: Jan-Espen Pettersen <sigsegv@radiotube.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Previous version was using incorrect union structures for non-AP
interfaces when adding and removing max_ratectrl_rateidx and
force_unicast_rateidx entries. Depending on the vif type, this ended
up in corrupting debugfs entries since the dentries inside different
union structures ended up going being on top of eachother.. As the
end result, debugfs files were being left behind with references to
freed data (instant kernel oops on access) and directories were not
removed properly when unloading mac80211 drivers. This patch fixes
those issues by using only a single union structure based on the vif
type.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
In the function mesh_table_grow, it is the new table not the argument table
that should be freed if the function fails (cf commit
bd9b448f4c)
The semantic match that detects this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression x;
expression E,f;
position p1,p2,p3;
identifier l;
statement S;
@@
x = mesh_table_alloc@p1(...)
...
if (x == NULL) S
... when != E = x
when != mesh_table_free(x)
goto@p2 l;
... when != E = x
when != f(...,x,...)
when any
(
return \(0\|x\);
|
return@p3 ...;
)
@script:python@
p1 << r.p1;
p2 << r.p2;
p3 << r.p3;
@@
print "%s: call on line %s not freed or saved before return on line %s via line %s" % (p1[0].file,p1[0].line,p3[0].line,p2[0].line)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The previous code was using IWEVCUSTOM to report IEs from AssocReq and
AssocResp frames into user space. This can easily hit the 256 byte
limit (IW_CUSTOM_MAX) with APs that include number of vendor IEs in
AssocResp. This results in the event message not being sent and dmesg
showing "wlan0 (WE) : Wireless Event too big (366)" type of errors.
Convert mac80211 to use IWEVASSOCREQIE/IWEVASSOCRESPIE to avoid the
issue of being unable to send association IEs as wireless events. These
newer event types use binary encoding and larger maximum size
(IW_GENERIC_IE_MAX = 1024), so the likelyhood of not being able to send
the IEs is much smaller than with IWEVCUSTOM. As an extra benefit, the
code is also quite a bit simpler since there is no need to allocate an
extra buffer for hex encoding.
Signed-off-by: Jouni Malinen <jouni.malinen@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Trivial patch adding a missing line break on
rfkill_claim_show().
Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.co>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
bintval is set to the initial value at .config_interface which is too
late, since it overwrites previously set value from .config. Move the
initialization to the .add_interface.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Nick Kossifidis <mickflemm@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Beacons setup and config was racy with beacon send. Ensure that
ISR and reset functions see consistent state of bbuf.
Use also dev_kfree_skb_any in ath5k_txbuf_free since we call it
from atomic now.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Nick Kossifidis <mickflemm@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
When the AP rejects a Shared Key authentication request, try Open System
auth too.
Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Return errors from request_firmware() (like other drivers that do
firmware load on device open) and make up plausible codes for other
error conditions. Gives userspace tools like NetworkManager a clue that
firmware may be missing when the result of setting IFF_UP is ENOENT.
Signed-off-by: Dan Williams <dcbw@redhat.com>
v2: fix reversed check of atmel_wakeup_firmware() in probe_atmel_card()
Signed-off-by: John W. Linville <linville@tuxdriver.com>
The multi queue support is still disabled by default for the bnx2x
(needs some more testing and validation), but there are 2 obvious bug in
it which are fixed in this patch
Signed-off-by: Yitchak Gertner <gertner@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fixing the order of enabling and disabling NAPI and the interrupts
Signed-off-by: Yitchak Gertner <gertner@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Load failures were not handled correctly
Signed-off-by: Yitchak Gertner <gertner@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The TPA initialization is part of the FW internal memory initialization
and so it is moved to the appropriate function
Signed-off-by: Yitchak Gertner <gertner@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Increasing the lock timeout to 5 seconds instead of 1 second to minimize
the chance of failures due to timeout
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
After iSCSI boot, the HW lock should only protect the flag so only the
first function will reset the chip and not then entire chip reset
process
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The A1021G board is also using the fan failure mechanism in the same way
the A1022G board does
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The has Rx work check was wrong: when the FW was at the end of the page,
the driver was already at the beginning of the next page. Since the
check only validated that both driver and FW are pointing to the same
place, it concluded that there is still work to be done. This caused
some serious issues including long latency results on ping-pong test and
lockups while unloading the driver in that condition.
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Braino: net.ipv6 in ipv6 skeleton has no business in rotable
class
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
net.ipv4.neigh should be a part of skeleton to avoid ordering problems
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The structure used for SCTP_AUTH_KEY option contains a
length that needs to be verfied to prevent buffer overflow
conditions. Spoted by Eugene Teo <eteo@redhat.com>.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The mv643xx_eth hardware ignores the lower three bits of the buffer
size field in receive descriptors, causing the reception of full-sized
packets to fail at some MTUs. Fix this by rounding the size of
allocated receive buffers up to a multiple of eight bytes.
While we are at it, add a bit of extra space to each receive buffer so
that we can handle multiple vlan tags on ingress.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
When we are low on memory, the assumption that every descriptor in the
receive ring will have an skbuff associated with it does not hold.
rxq_process() was assuming that if the receive descriptor it is working
on is not owned by the hardware, it can safely be processed and handed
to the networking stack. But a descriptor in the receive ring not being
owned by the hardware can also happen when we are low on memory and did
not manage to refill the receive ring fully.
This patch changes rxq_process()'s bailout condition from "the first
receive descriptor to be processed is owned by the hardware" to "the
first receive descriptor to be processed is owned by the hardware OR
the number of valid receive descriptors in the ring is zero".
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Nicolas Pitre noted that mv643xx_eth_poll was incorrectly using
non-IRQ-safe locks while checking whether to wake up the netdevice's
transmit queue. Convert the locking to *_irq() variants, since we
are running from softirq context where interrupts are enabled.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Commit 12e4ab79cd ("mv643xx_eth: be
more agressive about RX refill") changed the condition for the receive
out-of-memory timer to be scheduled from "the receive ring is empty"
to "the receive ring is not full".
This can lead to a situation where the receive out-of-memory timer is
pending because a previous rxq_refill() didn't manage to refill the
receive ring entirely as a result of being out of memory, and
rxq_refill() is then called again as a side effect of a packet receive
interrupt, and that rxq_refill() call then again does not succeed to
refill the entire receive ring with fresh empty skbuffs because we are
still out of memory, and then tries to call add_timer() on the already
scheduled out-of-memory timer.
This patch fixes this issue by changing the add_timer() call in
rxq_refill() to a mod_timer() call. If the OOM timer was not already
scheduled, this will behave as before, whereas if it was already
scheduled, this patch will push back its firing time a bit, which is
safe because we've (unsuccessfully) attempted to refill the receive
ring just before we do this.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
When a receive interrupt occurs, mv643xx_eth would first process the
receive descriptors and then ACK the receive interrupt, instead of the
other way round.
This would leave a small race window between processing the last
receive descriptor and clearing the receive interrupt status in which
a new packet could come in, which would then 'rot' in the receive
ring until the next receive interrupt would come in.
Fix this by ACKing (clearing) the receive interrupt condition before
processing the receive descriptors.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
This fixes a problem spotted with zebra, but not sure if it is
necessary a kernel problem. With IPV6 when an address is added to an
interface, Zebra creates a duplicate RIB entry, one as a connected
route, and other as a kernel route.
When an address is added to an interface the RTN_NEWADDR message
causes Zebra to create a connected route. In IPV4 when an address is
added to an interface a RTN_NEWROUTE message is set to user space with
the protocol RTPROT_KERNEL. Zebra ignores these messages, because it
already has the connected route.
The problem is that route created in IPV6 has route protocol ==
RTPROT_BOOT. Was this a design decision or a bug? This fixes it. Same
patch applies to both net-2.6 and stable.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since some qdiscs call qdisc_tree_decrease_qlen() (so qdisc_lookup())
without rtnl_lock(), adding and deleting from a qdisc list needs
additional locking. This patch adds global spinlock qdisc_list_lock
and wrapper functions for modifying the list. It is considered as a
temporary solution until hfsc_dequeue(), netem_dequeue() and
tbf_dequeue() (or qdisc_tree_decrease_qlen()) are redone.
With feedback from Herbert Xu and David S. Miller.
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
dev_deactivate() can skip rescheduling of a qdisc by qdisc_watchdog()
or other timer calling netif_schedule() after dev_queue_deactivate().
We prevent this checking aliveness before scheduling the timer. Since
during deactivation the root qdisc is available only as qdisc_sleeping
additional accessor qdisc_root_sleeping() is created.
With feedback from Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
All of the SCTP-AUTH socket options could cause a panic
if the extension is disabled and the API is envoked.
Additionally, there were some additional assumptions that
certain pointers would always be valid which may not
always be the case.
This patch hardens the API and address all of the crash
scenarios.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
After commit a97c9bf33f (fix cramfs
making duplicate entries in inode cache) in kernel 2.6.14, named-pipe
on cramfs does not work properly.
It seems the commit make all named-pipe on cramfs share their inode
(and named-pipe buffer).
Make ..._test() refuse to merge inodes with ->i_ino == 1, take inode setup
back to get_cramfs_inode() and make ->drop_inode() evict ones with ->i_ino
== 1 immediately.
Reported-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@kernel.org> [2.6.14 and later]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes kernel BUG at lib/radix-tree.c:473.
Previously the handler was incidentally provided by tmpfs but this was
removed with:
commit 14fcc23fdc
Author: Hugh Dickins <hugh@veritas.com>
Date: Mon Jul 28 15:46:19 2008 -0700
tmpfs: fix kernel BUG in shmem_delete_inode
relying on this behaviour was incorrect in any case and the BUG also
appeared when the device node was on an ext3 filesystem.
v2: override a_ops at open() time rather than mmap() time to minimise
races per AKPM's concerns.
Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Jaya Kumar <jayakumar.lkml@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Kel Modderman <kel@otaku42.de>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <stable@kernel.org> [14fcc23fd is in 2.6.25.14 and 2.6.26.1]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On a PowerPC board with ds1374 RTC I'm getting this error while RTC tries
to probe:
rtc-ds1374 0-0068: unable to request IRQ
This happens because I2C probing code (drivers/of/of_i2c.c) is specifying
IRQ0 for 'no irq' case, which is correct.
The driver handles this incorrectly, though. This patch fixes it.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
XIP can call into get_xip_mem concurrently with the same file,offset with
create=1. This usually maps down to get_block, which expects the page
lock to prevent such a situation. This causes ext2 to explode for one
reason or another.
Serialise those calls for the moment. For common usages today, I suspect
get_xip_mem rarely is called to create new blocks. In future as XIP
technologies evolve we might need to look at which operations require
scalability, and rework the locking to suit.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Acked-by: Carsten Otte <cotte@freenet.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
XIP has a race between sparse pages being inserted into page tables, and
sparse pages being zapped when its time to put a non-sparse page in.
What can happen is that a process can be left with a dangling sparse page
in a MAP_SHARED mapping, while the rest of the world sees the non-sparse
version. Ie. data corruption.
Guard these operations with a seqlock, making fault-in-sparse-pages the
slowpath, and try-to-unmap-sparse-pages the fastpath.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Acked-by: Carsten Otte <cotte@freenet.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a race with dirty page accounting where a page may not properly
be accounted for.
clear_page_dirty_for_io() calls page_mkclean; then TestClearPageDirty.
page_mkclean walks the rmaps for that page, and for each one it cleans and
write protects the pte if it was dirty. It uses page_check_address to
find the pte. That function has a shortcut to avoid the ptl if the pte is
not present. Unfortunately, the pte can be switched to not-present then
back to present by other code while holding the page table lock -- this
should not be a signal for page_mkclean to ignore that pte, because it may
be dirty.
For example, powerpc64's set_pte_at will clear a previously present pte
before setting it to the desired value. There may also be other code in
core mm or in arch which do similar things.
The consequence of the bug is loss of data integrity due to msync, and
loss of dirty page accounting accuracy. XIP's __xip_unmap could easily
also be unreliable (depending on the exact XIP locking scheme), which can
lead to data corruption.
Fix this by having an option to always take ptl to check the pte in
page_check_address.
It's possible to retain this optimization for page_referenced and
try_to_unmap.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Jared Hulbert <jaredeh@gmail.com>
Cc: Carsten Otte <cotte@freenet.de>
Cc: Hugh Dickins <hugh@veritas.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When user calls sys_setpriority(PRIO_PGRP ...) on a NPTL style multi-LWP
process, only the task leader of the process is affected, all other
sibling LWP threads didn't receive the setting. The problem was that the
iterator used in sys_setpriority() only iteartes over one task for each
process, ignoring all other sibling thread.
Introduce a new macro do_each_pid_thread / while_each_pid_thread to walk
each thread of a process. Convert 4 call sites in {set/get}priority and
ioprio_{set/get}.
Signed-off-by: Ken Chen <kenchen@google.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix bug: does nor properply resume after suspend mem
Fix for PM_SUSPEND_MEM: Save and restore peripheral base and DMA registers
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Acked-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Absolute alignment requirements may never be applied to node-relative
offsets. Andreas Herrmann spotted this flaw when a bootmem allocation on
an unaligned node was itself not aligned because the combination of an
unaligned node with an aligned offset into that node is not garuanteed to
be aligned itself.
This patch introduces two helper functions that align a node-relative
index or offset with respect to the node's starting address so that the
absolute PFN or virtual address that results from combining the two
satisfies the requested alignment.
Then all the broken ALIGN()s in alloc_bootmem_core() are replaced by these
helpers.
Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Reported-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Debugged-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Reviewed-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Tested-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Release cmap memory allocated in the probe function.
Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With commit 5ad31a5751 ("rtc: remove BKL
for ioctl()"), RTC_UIE_ON ioctl cause double lock on rtc->ops_lock.
The ops_lock must not be held while set_uie() calls rtc_read_time()
which takes the lock. Also clear_uie() does not need ops_lock. This
patch fixes return value of RTC_UIE_OFF ioctl too.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: David Brownell <david-b@pacbell.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In case the binfmt_misc binary handler is registered *before* the e.g.
script one (when for example being compiled as a module) the following
situation may occur:
1. user launches a script, whose interpreter is a misc binary;
2. the load_misc_binary sets the misc_bang and returns -ENOEVEC,
since the binary is a script;
3. the load_script_binary loads one and calls for search_binary_hander
to run the interpreter;
4. the load_misc_binary is called again, but refuses to load the
binary due to misc_bang bit set.
The fix is to move the misc_bang setting lower - prior to the actual
call to the search_binary_handler.
Caused by the commit 3a2e7f47 (binfmt_misc.c: avoid potential kernel
stack overflow)
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Reported-by: Kirill A. Shutemov <kirill@shutemov.name>
Tested-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: <stable@kernel.org> [2.6.26.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Alexander Duyck