Extend the qdio API to allow polling in the upper-layer driver. This
is needed by qeth to use NAPI.
To use the new interface the upper-layer driver must specify the
queue_start_poll(). This callback is used to signal the upper-layer
driver that is has initiative and must process the inbound queue by
calling qdio_get_next_buffers(). If the upper-layer driver wants to
stop polling it calls qdio_start_irq().
Since adapter interrupts are not completely stoppable qdio implements
a software bit QDIO_QUEUE_IRQS_DISABLED to safely disable interrupts for an
input queue.
The old interface is preserved and will be used as is by zfcp.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove qdio API wrappers used by qeth and replace them by calling the
appropriate functions directly.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Don't convert timestamps to microseconds, use timestamps returned by
get_clock() directly.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If adapter interrupts are not available and traditional IO interrupts
are used for qdio the inbound tasklet continued to run if new data
arrived. That could possibly block other tasklets scheduled on the
same CPU. If new data arrives schedule the tasklet again instead of
directly processing the new data.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add missing increment for the qdio interrupt counter.
Signed-off-by: Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Add a missing bracket to only log the outbound handler event in the
appropriate case.
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Introduce the MACHINE_IS_LPAR flag for code that should only be
executed if Linux is running in an LPAR.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add counters for the number of processed SBALs. The numbers summarize
how many SBALs were processed at each queue scan and indicate the
utilization of the queue. Furthermore the number of unsuccessfull
queue scans, SBAL errors and the total number of processed
SBALs are accounted.
Also regroup struct qdio_q to move read-mostly and write-mostly data
into different cachelines.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If a CHPID is offline during a device shutdown the ccw_device_halt|clear
may fail and the qdio device stays in state STOPPED until the shutdown is
finished. If an interrupt occurs before the device is set to INACTIVE
the STOPPED state triggers a WARN_ON in the interrupt handler.
Prevent this WARN_ON by catching the STOPPED state in the interrupt
handler.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Inbound traffic handling may hang if next buffer to check is in
state ERROR, polling is stopped and the final check for further
available inbound buffers disregards buffers in state ERROR.
This patch includes state ERROR when checking availability of
more inbound buffers.
Cc: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Revamp the qdio performance statistics and move them from procfs to
debugfs using the seq_file interface. Since the statistics are not
intended for the general user the removal of /proc/qdio_perf should
not surprise anyone.
The per device statistics are disabled by default, writing 1 to
/<debugfs mountpoint>/qdio/<device bus ID>/statistics enables the
statistics for the given device.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add a counter to the qdio performance statistics that indicates that no
free buffers were left in the input queue. If the counter gets increased
it means that the qdio adapter filled all available buffers and possibly
had more buffers ready but could not transmit them.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If input buffers stay in primed state qdio may not receive further interrupts
for the input queue depending on the firmware. That can cause a connection
hang on OSA cards.
Change the state of all primed input buffers that are not acknowledged to
not initialized.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Even if turned off the debug message overhead is measurable in the hot path.
Reduce the number of debug message calls in do_QDIO and qdio_kick_handler.
Also use hex numbers to save space in the debug entries.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
With commit c38f960809 polling was
stopped for the queue even if new data is available.
Return immediately after scheduling the queue tasklet if the queue
is not done.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Remove unneeded sanity checks from do_QDIO since this is the hot path.
Change the type of bufnr and count to unsigned int so the check for the
maximum value works.
Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
It is not required to change the state of primed SBALs. Leaving them
primed saves a SQBS instruction under z/VM.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
For devices without QIOASSIST primed SBALS were extracted in a loop.
Remove the loop since get_buf_states can already return more than
one primed SBAL.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The check whether qdio runs under z/VM was incorrect since SIGA-Sync is not
set if the device runs with QIOASSIST. Use MACHINE_IS_VM instead to prevent
polling under z/VM.
Merge qdio_inbound_q_done and tiqdio_is_inbound_q_done.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Move the adapter interrupt tasklet function to the qdio main code
since all the functions used by the tasklet are located there.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Do not go beyond ARRAY_SIZE of irq_ptr->{in,out}put_qs
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The check for the device status in qdio_establish_handle_irq()
had dead code. Remove the unused code and simplify the error
handling.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The QDIO ccw devices are started by ccw_device_start so no timeout
can occur for the interrupt handler. Remove the dead code.
In case of an I/O error set the device state to error and wake up
a possibly running qdio_shutdown waiter.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The inbound and outbound handlers are nearly identical if the outbound
handler uses first_to_check as end index instead of last_move. Since both
values are identical at that point the handlers can be merged.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Errors from SIGA instructions are stored in the per queue qdio_error
and reported back when the queue handler is called. That opens a race
when multiple error conditions occur simultanously.
Report SIGA errors immediately in the return value of do_QDIO so the
upper layer can react and SIGA errors no longer interfere with other
errors.
Move the SIGA error handling in qeth from the outbound handler to
qeth_flush_buffers.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
The index value that indicated that the input queue moved was also used to
store the index of the first acknowledged buffer. For non-qebsm only the
newest buffer is acknowledged which may be different from the last move index
so two seperate values are needed to track the input queue.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The ACKnowledgement state should be set on the newest SBAL so an
adapter interrupt surpression check needs to scan fewer SBALs.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
qdio_cleanup is a wrapper function that should call qdio_shutdown and
qdio_free. qdio_free was not called if an error occured in qdio_shutdown
resulting in a missing free of allocated resources.
Call qdio_free regardless of the return value of qdio_shutdown.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The queue tasklets were stopped with tasklet_disable. Although tasklet_disable
prevents the tasklet from beeing executed it is still possible that a tasklet
is scheduled on a CPU at that point. A following qdio_establish calls
tasklet_init which clears the tasklet count and the tasklet state leading to
the following Oops:
<2>kernel BUG at kernel/softirq.c:392!
<4>illegal operation: 0001 [#1] SMP
<4>Modules linked in: iptable_filter ip_tables x_tables dm_round_robin dm_multipath scsi_dh sg sd_mod crc_t10dif nfs lockd nfs
_acl sunrpc fuse loop dm_mod qeth_l3 ipv6 zfcp qeth scsi_transport_fc qdio scsi_tgt scsi_mod chsc_sch ccwgroup dasd_eckd_mod dasdm
od ext3 mbcache jbd
<4>Supported: Yes
<4>CPU: 0 Not tainted 2.6.27.13-1.1.mz13-default #1
<4>Process blast.LzS_64 (pid: 16445, task: 000000006cc02538, ksp: 000000006cb67998)
<4>Krnl PSW : 0704c00180000000 00000000001399f4 (tasklet_action+0xc8/0x1d4)
<4> R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 EA:3
<4>Krnl GPRS: ffffffff00000030 0000000000000002 0000000000000002 fffffffffffffffe
<4> 000000000013aabe 00000000003b6a18 fffffffffffffffd 0000000000000000
<4> 00000000006705a8 000000007d0914a8 000000007d0914b0 000000007fecfd30
<4> 0000000000000000 00000000003b63e8 000000007fecfd90 000000007fecfd30
<4>Krnl Code: 00000000001399e8: b9200021 cgr %r2,%r1
<4> 00000000001399ec: a7740004 brc 7,1399f4
<4> 00000000001399f0: a7f40001 brc 15,1399f2
<4> >00000000001399f4: c0100027e8ee larl %r1,636bd0
<4> 00000000001399fa: bf1f1008 icm %r1,15,8(%r1)
<4> 00000000001399fe: a7840019 brc 8,139a30
<4> 0000000000139a02: c0300027e8ef larl %r3,636be0
<4> 0000000000139a08: e3c030000004 lg %r12,0(%r3)
<4>Call Trace:
<4>([<0000000000139c12>] tasklet_hi_action+0x112/0x1d4)
<4> [<000000000013aabe>] __do_softirq+0xde/0x1c4
<4> [<000000000010fa2e>] do_softirq+0x96/0xb0
<4> [<000000000013a8d8>] irq_exit+0x70/0xcc
<4> [<000000000010d1d8>] do_extint+0xf0/0x110
<4> [<0000000000113b10>] ext_no_vtime+0x16/0x1a
<4> [<000003e0000a3662>] ext3_dirty_inode+0xe6/0xe8 [ext3]
<4>([<00000000001f6cf2>] __mark_inode_dirty+0x52/0x1d4)
<4> [<000003e0000a44f0>] ext3_ordered_write_end+0x138/0x190 [ext3]
<4> [<000000000018d5ec>] generic_perform_write+0x174/0x230
<4> [<0000000000190144>] generic_file_buffered_write+0xb4/0x194
<4> [<0000000000190864>] __generic_file_aio_write_nolock+0x418/0x454
<4> [<0000000000190ee2>] generic_file_aio_write+0x76/0xe4
<4> [<000003e0000a05c2>] ext3_file_write+0x3e/0xc8 [ext3]
<4> [<00000000001cc2fe>] do_sync_write+0xd6/0x120
<4> [<00000000001ccfc8>] vfs_write+0xac/0x184
<4> [<00000000001cd218>] SyS_write+0x68/0xe0
<4> [<0000000000113402>] sysc_noemu+0x10/0x16
<4> [<0000020000043188>] 0x20000043188
<4>Last Breaking-Event-Address:
<4> [<00000000001399f0>] tasklet_action+0xc4/0x1d4
<6>qdio: 0.0.c61b ZFCP on SC f67 using AI:1 QEBSM:0 PCI:1 TDD:1 SIGA: W AOP
<4> <0>Kernel panic - not syncing: Fatal exception in interrupt
Use tasklet_kill instead of tasklet_disbale. Since tasklet_schedule must not be
called after tasklet_kill use the QDIO_IRQ_STATE_STOPPED to inidicate that a
queue is going down and prevent further tasklet schedules in that case.
Remove superflous tasklet_schedule from input queue setup, at that time
the queues are not ready so the schedule results in a NOP.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Remove the call to qdio_shutdown from qdio_activate since the upper-layer
drivers are responsible to call qdio_shutdown when qdio_activate returns
with an error.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add a mutex to protect the tiq_list. Although reading the list is done
using RCU adding and removing elements from the list must still
happen locked since multiple qdio devices may change the list in parallel
otherwise.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
When I review ocfs2 code, find there are 2 typos to "successfull". After
doing grep "successfull " in kernel tree, 22 typos found totally -- great
minds always think alike :)
This patch fixes all the similar typos. Thanks for Randy's ack and comments.
Signed-off-by: Coly Li <coyli@suse.de>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Roland Dreier <rolandd@cisco.com>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hipersocket connections can encounter temporary busy conditions.
In case of the busy bit set we retry the SIGA operation immediatelly.
If the busy condition still persists after 100 ms we fail and report
the error to the upper layer. The second stage retry logic is removed.
In case of ongoing busy conditions the upper layer needs to reset the
connection.
The reporting of a SIGA error is now done synchronously to allow the
network driver to requeue the buffers. Also no error trace is created
for the temporary SIGA errors so the error message view is not flooded.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
- Use automatic acknowledgement of incoming buffers in QEBSM mode
- Move ACK for non-QEBSM mode always to the newest buffer to prevent
a race with qdio_stop_polling
- Remove the polling spinlock, the upper layer drivers return new buffers
in the same code path and could not run in parallel
- Don't flood the error log in case of no-target-buffer-empty
- In handle_inbound we check if we would overwrite an ACK'ed buffer, if so
advance the pointer to the oldest ACK'ed buffer so we don't overwrite an
empty buffer in qdio_stop_polling
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
- make qdio_trace a per device view
- remove s390dbf exceptions
- remove CONFIG_QDIO_DEBUG, not needed anymore if we check for the level
before calling sprintf
- use snprintf for dbf entries
- add start markers to see if the dbf view wrapped
- add a global error view for all queues
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The QEBSM instructions are only available for CONFIG_64BIT, they are not
used under 31 bit. Make compiler happy about the false positive:
drivers/s390/cio/qdio_main.c: In function ?qdio_inbound_q_done?:
drivers/s390/cio/qdio_main.c:532: warning: ?state? may be used uninitialized in this function
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add counters for the eqbs and sqbs instructions that indicate how often
we issued the instructions and how often the instructions returned with
less buffers than specified.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
qeth needs to get the port count information before
qdio has allocated a page for the chsc operation.
Extend qdio_get_ssqd_desc() to store the data in the
specified structure.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
In case of I/O errors on a qdio subchannel qdio_shutdown may be
called twice by the qdio driver and by zfcp. Remove the
superfluous shutdown from qdio and let the upper layer driver
handle the error condition.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Add support for z10 HiperSockets multiwrite SBALs on output
queues. This is used on LPAR with EDDP enabled devices.
Signed-off-by: Klaus-Dieter Wacker <kdwacker@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Use dev_name() in the new qdio driver.
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
If an asynchronous HiperSockets queue runs full, no further packet
can be sent. In this case the next initiative to give transmitted
skbs back to the stack is triggered only by a 10-seconds qdio timer.
This timer has been introduced for low multicast traffic scenarios
to guarantee freeing of skbs in a limited amount of time. For high
HiperSocket multicast traffic scenarios progress checking on the
outbound queue should be enforced by tasklet rescheduling.
Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Increasing the qdio reference count for every used subchannel
is unnecessary since unloading qdio (if build as a module) is
only possible if other modules that use qdio are unloaded.
Unloading modules that use qdio in turn requires that these
modules shut down all qdio subchannels. Therefore the additional
module_get reference is not needed.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Improve s390 debug feature usage:
- log busy bit in dbf
- increase size of dbf views
- consistent logging of qdio api calls to setup view
- print subchannel number so one can associate the interface
with the dbf data
- only log events to one view
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
kzalloc does not guarantee the required alignment of qdr to page size,
use get_zeroed_page instead.
Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Jan Glauber