Al Viro [Tue, 8 Oct 2013 13:11:48 +0000 (09:11 -0400)]
make dump_emit() use vfs_write() instead of banging at ->f_op->write directly
... and deal with short writes properly - the output might be to pipe, after
all; as it is, e.g. no-MMU case of elf_fdpic coredump can write a whole lot
more than a page worth of data at one call.
Al Viro [Sat, 5 Oct 2013 19:32:35 +0000 (15:32 -0400)]
new helper: dump_emit()
dump_write() analog, takes core_dump_params instead of file,
keeps track of the amount written in cprm->written and checks for
cprm->limit. Start using it in binfmt_elf.c...
Al Viro [Mon, 30 Sep 2013 02:06:07 +0000 (22:06 -0400)]
RCU'd vfsmounts
* RCU-delayed freeing of vfsmounts
* vfsmount_lock replaced with a seqlock (mount_lock)
* sequence number from mount_lock is stored in nameidata->m_seq and
used when we exit RCU mode
* new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its
caller knows that vfsmount will have no surviving references.
* synchronize_rcu() done between unlocking namespace_sem in namespace_unlock()
and doing pending mntput().
* new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence
number against seq, then grabs reference to mnt. Then it rechecks mount_lock
again to close the race and either returns success or drops the reference it
has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can
simply decrement the refcount and sod off - aforementioned synchronize_rcu()
makes sure that final mntput() won't come until we leave RCU mode. We need
that, since we don't want to end up with some lazy pathwalk racing with
umount() and stealing the final mntput() from it - caller of umount() may
expect it to return only once the fs is shut down and we don't want to break
that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do
full-blown mntput() in case of mount_lock sequence number mismatch happening
just as we'd grabbed the reference, but in those cases we won't be stealing
the final mntput() from anything that would care.
* mntput_no_expire() doesn't lock anything on the fast path now. Incidentally,
SMP and UP cases are handled the same way - no ifdefs there.
* normal pathname resolution does *not* do any writes to mount_lock. It does,
of course, bump the refcounts of vfsmount and dentry in the very end, but that's
it.
Miklos Szeredi [Tue, 1 Oct 2013 14:44:54 +0000 (16:44 +0200)]
vfs: introduce d_instantiate_no_diralias()
...which just returns -EBUSY if a directory alias would be created.
This is to be used by fuse mkdir to make sure that a buggy or malicious
userspace filesystem doesn't do anything nasty. Previously fuse used a
private mutex for this purpose, which can now go away.
Al Viro [Tue, 1 Oct 2013 20:11:26 +0000 (16:11 -0400)]
split __lookup_mnt() in two functions
Instead of passing the direction as argument (and checking it on every
step through the hash chain), just have separate __lookup_mnt() and
__lookup_mnt_last(). And use the standard iterators...
Al Viro [Mon, 16 Sep 2013 00:45:11 +0000 (20:45 -0400)]
ecryptfs: don't leave RCU pathwalk immediately
If the underlying dentry doesn't have ->d_revalidate(), there's no need to
force dropping out of RCU mode. All we need for that is to make freeing
ecryptfs_dentry_info RCU-delayed.
Pull SCSI target fixes from Nicholas Bellinger:
"Here are the outstanding target fixes queued up for v3.12-rc4 code.
The highlights include:
- Make vhost/scsi tag percpu_ida_alloc() use GFP_ATOMIC
- Allow sess_cmd_map allocation failure fallback to use vzalloc
- Fix COMPARE_AND_WRITE se_cmd->data_length bug with FILEIO backends
- Fixes for COMPARE_AND_WRITE callback recursive failure OOPs + non
zero scsi_status bug
- Make iscsi-target do acknowledgement tag release from RX context
- Setup iscsi-target with extra (cmdsn_depth / 2) percpu_ida tags
Also included is a iscsi-target patch CC'ed for v3.10+ that avoids
legacy wait_for_task=true release during fast-past StatSN
acknowledgement, and two other SRP target related patches that address
long-standing issues that are CC'ed for v3.3+.
Extra thanks to Thomas Glanzmann for his testing feedback with
COMPARE_AND_WRITE + EXTENDED_COPY VAAI logic"
* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
iscsi-target; Allow an extra tag_num / 2 number of percpu_ida tags
iscsi-target: Perform release of acknowledged tags from RX context
iscsi-target: Only perform wait_for_tasks when performing shutdown
target: Fail on non zero scsi_status in compare_and_write_callback
target: Fix recursive COMPARE_AND_WRITE callback failure
target: Reset data_length for COMPARE_AND_WRITE to NoLB * block_size
ib_srpt: always set response for task management
target: Fall back to vzalloc upon ->sess_cmd_map kzalloc failure
vhost/scsi: Use GFP_ATOMIC with percpu_ida_alloc for obtaining tag
ib_srpt: Destroy cm_id before destroying QP.
target: Fix xop->dbl assignment in target_xcopy_parse_segdesc_02
Linus Torvalds [Sun, 6 Oct 2013 20:35:15 +0000 (13:35 -0700)]
Merge branch 'fixes' of git://git.infradead.org/users/vkoul/slave-dma
Pull slave-dmaengine fixes from Vinod Koul:
"Here is the slave dmanegine fixes. We have the fix for deadlock issue
on imx-dma by Michael and Josh's edma config fix along with author
change"
* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
dmaengine: imx-dma: fix callback path in tasklet
dmaengine: imx-dma: fix lockdep issue between irqhandler and tasklet
dmaengine: imx-dma: fix slow path issue in prep_dma_cyclic
dma/Kconfig: Make TI_EDMA select TI_PRIV_EDMA
edma: Update author email address
Linus Torvalds [Sat, 5 Oct 2013 19:17:24 +0000 (12:17 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
Pull btrfs fixes from Chris Mason:
"This is a small collection of fixes, including a regression fix from
Liu Bo that solves rare crashes with compression on.
I've merged my for-linus up to 3.12-rc3 because the top commit is only
meant for 3.12. The rest of the fixes are also available in my master
branch on top of my last 3.11 based pull"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
btrfs: Fix crash due to not allocating integrity data for a bioset
Btrfs: fix a use-after-free bug in btrfs_dev_replace_finishing
Btrfs: eliminate races in worker stopping code
Btrfs: fix crash of compressed writes
Btrfs: fix transid verify errors when recovering log tree
Linus Torvalds [Sat, 5 Oct 2013 19:11:40 +0000 (12:11 -0700)]
Merge tag 'gpio-v3.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio
Pull GPIO fixes from Linus Walleij:
"Two patches for the OMAP driver, dealing with setting up IRQs properly
on the device tree boot path"
* tag 'gpio-v3.12-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
gpio/omap: auto-setup a GPIO when used as an IRQ
gpio/omap: maintain GPIO and IRQ usage separately
Linus Torvalds [Sat, 5 Oct 2013 18:54:10 +0000 (11:54 -0700)]
Merge tag 'usb-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg KH:
"Here are none fixes for various USB driver problems. The majority are
gadget/musb fixes, but there are some new device ids in here as well"
* tag 'usb-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
usb: chipidea: add Intel Clovertrail pci id
usb: gadget: s3c-hsotg: fix can_write limit for non-periodic endpoints
usb: gadget: f_fs: fix error handling
usb: musb: dsps: do not bind to "musb-hdrc"
USB: serial: option: Ignore card reader interface on Huawei E1750
usb: musb: gadget: fix otg active status flag
usb: phy: gpio-vbus: fix deferred probe from __init
usb: gadget: pxa25x_udc: fix deferred probe from __init
usb: musb: fix otg default state
Linus Torvalds [Sat, 5 Oct 2013 18:26:19 +0000 (11:26 -0700)]
Merge tag 'tty-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty fixes from Greg KH:
"Here are two tty driver fixes for 3.12-rc4.
One fixes the reported regression in the n_tty code that a number of
people found recently, and the other one fixes an issue with xen
consoles that broke in 3.10"
* tag 'tty-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
xen/hvc: allow xenboot console to be used again
tty: Fix pty master read() after slave closes
Darrick J. Wong [Fri, 20 Sep 2013 03:37:07 +0000 (20:37 -0700)]
btrfs: Fix crash due to not allocating integrity data for a bioset
When btrfs creates a bioset, we must also allocate the integrity data pool.
Otherwise btrfs will crash when it tries to submit a bio to a checksumming
disk:
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Linus Torvalds [Sat, 5 Oct 2013 03:50:16 +0000 (20:50 -0700)]
Merge branch 'for-linus' of git://git.samba.org/sfrench/cifs-2.6
Pull CIFS fixes from Steve French:
"Small set of cifs fixes. Most important is Jeff's fix that works
around disconnection problems which can be caused by simultaneous use
of user space tools (starting a long running smbclient backup then
doing a cifs kernel mount) or multiple cifs mounts through a NAT, and
Jim's fix to deal with reexport of cifs share.
I expect to send two more cifs fixes next week (being tested now) -
fixes to address an SMB2 unmount hang when server dies and a fix for
cifs symlink handling of Windows "NFS" symlinks"
* 'for-linus' of git://git.samba.org/sfrench/cifs-2.6:
[CIFS] update cifs.ko version
[CIFS] Remove ext2 flags that have been moved to fs.h
[CIFS] Provide sane values for nlink
cifs: stop trying to use virtual circuits
CIFS: FS-Cache: Uncache unread pages in cifs_readpages() before freeing them
Linus Torvalds [Sat, 5 Oct 2013 03:48:20 +0000 (20:48 -0700)]
Merge tag 'pci-v3.12-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
Pull PCI fix from Bjorn Helgaas:
"We merged what was intended to be an MMCONFIG cleanup, but in fact,
for systems without _CBA (which is almost everything), it broke
extended config space for domain 0 and it broke all config space for
other domains.
This reverts the change"
* tag 'pci-v3.12-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
Revert "x86/PCI: MMCONFIG: Check earlier for MMCONFIG region at address zero"
07f9b61c was intended to be a cleanup that didn't change anything, but in
fact, for systems without _CBA (which is almost everything), it broke
extended config space for domain 0 and all config space for other domains.
Linus Torvalds [Fri, 4 Oct 2013 22:03:42 +0000 (15:03 -0700)]
Merge tag 'pm+acpi-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI and power management fixes from Rafael Wysocki:
- The resume part of user space driven hibernation (s2disk) is now
broken after the change that moved the creation of memory bitmaps to
after the freezing of tasks, because I forgot that the resume utility
loaded the image before freezing tasks and needed the bitmaps for
that. The fix adds special handling for that case.
- One of recent commits changed the export of acpi_bus_get_device() to
EXPORT_SYMBOL_GPL(), which was technically correct but broke existing
binary modules using that function including one in particularly
widespread use. Change it back to EXPORT_SYMBOL().
- The intel_pstate driver sometimes fails to disable turbo if its
no_turbo sysfs attribute is set. Fix from Srinivas Pandruvada.
- One of recent cpufreq fixes forgot to update a check in cpufreq-cpu0
which still (incorrectly) treats non-NULL as non-error. Fix from
Philipp Zabel.
- The SPEAr cpufreq driver uses a wrong variable type in one place
preventing it from catching errors returned by one of the functions
called by it. Fix from Sachin Kamat.
* tag 'pm+acpi-3.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI: Use EXPORT_SYMBOL() for acpi_bus_get_device()
intel_pstate: fix no_turbo
cpufreq: cpufreq-cpu0: NULL is a valid regulator, part 2
cpufreq: SPEAr: Fix incorrect variable type
PM / hibernate: Fix user space driven resume regression
Linus Torvalds [Fri, 4 Oct 2013 21:47:22 +0000 (14:47 -0700)]
Merge tag 'xfs-for-linus-v3.12-rc4' of git://oss.sgi.com/xfs/xfs
Pull xfs bugfixes from Ben Myers:
"There are lockdep annotations for project quotas, a fix for dirent
dtype support on v4 filesystems, a fix for a memory leak in recovery,
and a fix for the build error that resulted from it. D'oh"
* tag 'xfs-for-linus-v3.12-rc4' of git://oss.sgi.com/xfs/xfs:
xfs: Use kmem_free() instead of free()
xfs: fix memory leak in xlog_recover_add_to_trans
xfs: dirent dtype presence is dependent on directory magic numbers
xfs: lockdep needs to know about 3 dquot-deep nesting
Ilya Dryomov [Wed, 2 Oct 2013 17:41:01 +0000 (20:41 +0300)]
Btrfs: fix a use-after-free bug in btrfs_dev_replace_finishing
free_device rcu callback, scheduled from btrfs_rm_dev_replace_srcdev,
can be processed before btrfs_scratch_superblock is called, which would
result in a use-after-free on btrfs_device contents. Fix this by
zeroing the superblock before the rcu callback is registered.
Cc: Stefan Behrens <sbehrens@giantdisaster.de> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Ilya Dryomov [Wed, 2 Oct 2013 16:39:50 +0000 (19:39 +0300)]
Btrfs: eliminate races in worker stopping code
The current implementation of worker threads in Btrfs has races in
worker stopping code, which cause all kinds of panics and lockups when
running btrfs/011 xfstest in a loop. The problem is that
btrfs_stop_workers is unsynchronized with respect to check_idle_worker,
check_busy_worker and __btrfs_start_workers.
E.g., check_idle_worker race flow:
btrfs_stop_workers(): check_idle_worker(aworker):
- grabs the lock
- splices the idle list into the
working list
- removes the first worker from the
working list
- releases the lock to wait for
its kthread's completion
- grabs the lock
- if aworker is on the working list,
moves aworker from the working list
to the idle list
- releases the lock
- grabs the lock
- puts the worker
- removes the second worker from the
working list
......
btrfs_stop_workers returns, aworker is on the idle list
FS is umounted, memory is freed
......
aworker is waken up, fireworks ensue
With this applied, I wasn't able to trigger the problem in 48 hours,
whereas previously I could reliably reproduce at least one of these
races within an hour.
Reported-by: David Sterba <dsterba@suse.cz> Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Liu Bo [Tue, 1 Oct 2013 15:49:49 +0000 (23:49 +0800)]
Btrfs: fix crash of compressed writes
The crash[1] is found by xfstests/generic/208 with "-o compress",
it's not reproduced everytime, but it does panic.
The bug is quite interesting, it's actually introduced by a recent commit
(573aecafca1cf7a974231b759197a1aebcf39c2a,
Btrfs: actually limit the size of delalloc range).
Btrfs implements delay allocation, so during writeback, we
(1) get a page A and lock it
(2) search the state tree for delalloc bytes and lock all pages within the range
(3) process the delalloc range, including find disk space and create
ordered extent and so on.
(4) submit the page A.
It runs well in normal cases, but if we're in a racy case, eg.
buffered compressed writes and aio-dio writes,
sometimes we may fail to lock all pages in the 'delalloc' range,
in which case, we need to fall back to search the state tree again with
a smaller range limit(max_bytes = PAGE_CACHE_SIZE - offset).
The mentioned commit has a side effect, that is, in the fallback case,
we can find delalloc bytes before the index of the page we already have locked,
so we're in the case of (delalloc_end <= *start) and return with (found > 0).
This ends with not locking delalloc pages but making ->writepage still
process them, and the crash happens.
This fixes it by just thinking that we find nothing and returning to caller
as the caller knows how to deal with it properly.
Josef Bacik [Mon, 30 Sep 2013 18:10:43 +0000 (14:10 -0400)]
Btrfs: fix transid verify errors when recovering log tree
If we crash with a log, remount and recover that log, and then crash before we
can commit another transaction we will get transid verify errors on the next
mount. This is because we were not zero'ing out the log when we committed the
transaction after recovery. This is ok as long as we commit another transaction
at some point in the future, but if you abort or something else goes wrong you
can end up in this weird state because the recovery stuff says that the tree log
should have a generation+1 of the super generation, which won't be the case of
the transaction that was started for recovery. Fix this by removing the check
and _always_ zero out the log portion of the super when we commit a transaction.
This fixes the transid verify issues I was seeing with my force errors tests.
Thanks,
Linus Torvalds [Fri, 4 Oct 2013 19:54:11 +0000 (12:54 -0700)]
selinux: remove 'flags' parameter from inode_has_perm
Every single user passes in '0'. I think we had non-zero users back in
some stone age when selinux_inode_permission() was implemented in terms
of inode_has_perm(), but that complicated case got split up into a
totally separate code-path so that we could optimize the much simpler
special cases.
See commit 2e33405785d3 ("SELinux: delay initialization of audit data in
selinux_inode_permission") for example.
Free the memory in error path of xlog_recover_add_to_trans().
Normally this memory is freed in recovery pass2, but is leaked
in the error path.
Signed-off-by: Mark Tinguely <tinguely@sgi.com> Reviewed-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 519ccb81ac1c8e3e4eed294acf93be00b43dcad6)
Dave Chinner [Sun, 29 Sep 2013 23:37:04 +0000 (09:37 +1000)]
xfs: dirent dtype presence is dependent on directory magic numbers
The determination of whether a directory entry contains a dtype
field originally was dependent on the filesystem having CRCs
enabled. This meant that the format for dtype beign enabled could be
determined by checking the directory block magic number rather than
doing a feature bit check. This was useful in that it meant that we
didn't need to pass a struct xfs_mount around to functions that
were already supplied with a directory block header.
Unfortunately, the introduction of dtype fields into the v4
structure via a feature bit meant this "use the directory block
magic number" method of discriminating the dirent entry sizes is
broken. Hence we need to convert the places that use magic number
checks to use feature bit checks so that they work correctly and not
by chance.
The current code works on v4 filesystems only because the dirent
size roundup covers the extra byte needed by the dtype field in the
places where this problem occurs.
Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Ben Myers <bpm@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit 367993e7c6428cb7617ab7653d61dca54e2fdede)
The lockdep annotation for dquot lock nesting only understands
locking for user and "other" dquots, not user, group and quota
dquots. Fix the annotations to match the locking heirarchy we now
have.
Reported-by: Michael L. Semon <mlsemon35@gmail.com> Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Ben Myers <bpm@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
(cherry picked from commit f112a049712a5c07de25d511c3c6587a2b1a015e)
Linus Torvalds [Fri, 4 Oct 2013 16:06:13 +0000 (09:06 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse
Pull fuse bugfixes from Miklos Szeredi:
"This contains two more fixes by Maxim for writeback/truncate races and
fixes for RCU walk in fuse_dentry_revalidate()"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
fuse: no RCU mode in fuse_access()
fuse: readdirplus: fix RCU walk
fuse: don't check_submounts_and_drop() in RCU walk
fuse: fix fallocate vs. ftruncate race
fuse: wait for writeback in fuse_file_fallocate()
Linus Torvalds [Fri, 4 Oct 2013 16:05:12 +0000 (09:05 -0700)]
Merge tag 'iommu-fixes-v3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu
Pull iommu fixes from Joerg Roedel:
"A couple of fixes from the IOMMU side:
- some small fixes for the new ARM-SMMU driver
- a register offset correction for VT-d
- add MAINTAINERS entry for drivers/iommu
Overall no really big or intrusive changes"
* tag 'iommu-fixes-v3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
x86/iommu: correct ICS register offset
MAINTAINERS: add overall IOMMU section
iommu/arm-smmu: don't enable SMMU device until probing has completed
iommu/arm-smmu: fix iommu_present() test in init
iommu/arm-smmu: fix a signedness bug
* tag 'arm64-stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64:
arm64: Remove duplicate DEBUG_STACK_USAGE config
arm64: include VIRTIO_{MMIO,BLK} in defconfig
arm64: include EXT4 in defconfig
arm64: fix possible invalid FPSIMD initialization state
arm64: use correct register width when retrieving ASID
arm64: avoid multiple evaluation of ptr in get_user/put_user()
Linus Torvalds [Fri, 4 Oct 2013 16:03:51 +0000 (09:03 -0700)]
Merge branch 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus
Pull MIPS fixes from Ralf Baechle:
"Two small fixes for 3.12 only this week. I have a few more fixes
pending but those are conceptually more complex so will have to wait
for a bit longer"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
MIPS: Fix forgotten preempt_enable() when CPU has inclusive pcaches
MIPS: Alchemy: MTX-1: fix incorrect placement of __initdata tag
Linus Torvalds [Fri, 4 Oct 2013 16:03:07 +0000 (09:03 -0700)]
Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
"Two simplefb fixes"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/simplefb: Mark framebuffer mem-resources as IORESOURCE_BUSY to avoid bootup warning
x86/simplefb: Fix overflow causing bogus fall-back
We need to free the ld_active list head before jumping into the callback
routine. Otherwise the callback could run into issue_pending and change
our ld_active list head we just going to free. This will run the channel
list into an currupted and undefined state.
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
dmaengine: imx-dma: fix lockdep issue between irqhandler and tasklet
The tasklet and irqhandler are using spin_lock while other routines are
using spin_lock_irqsave/restore. This leads to lockdep issues as
described bellow. This patch is changing the code to use
spinlock_irq_save/restore in both code pathes.
As imxdma_xfer_desc always gets called with spin_lock_irqsave lock held,
this patch also removes the spare call inside the routine to avoid
double locking.
dmaengine: imx-dma: fix slow path issue in prep_dma_cyclic
When perparing cyclic_dma buffers by the sound layer, it will dump the
following lockdep trace. The leading snd_pcm_action_single get called
with read_lock_irq called. To fix this, we change the kcalloc call from
GFP_KERNEL to GFP_ATOMIC.