Henrik Rydberg [Tue, 9 Nov 2010 15:15:09 +0000 (15:15 +0000)]
hwmon: (applesmc) Simplify feature sysfs handling
Given the dynamic node construction method, the setup of the
accelerometer, light sensor and keyboard backlight sysfs nodes
can be simplified. This patch does not contain any logic changes.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Henrik Rydberg [Tue, 9 Nov 2010 15:15:08 +0000 (15:15 +0000)]
hwmon: (applesmc) Dynamic creation of fan files
With the dynamic temperature group in place, the setup of fans
can be simplified. This patch sets up the fans dynamically, removing
a hundred lines of code.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Henrik Rydberg [Wed, 10 Nov 2010 10:58:05 +0000 (10:58 +0000)]
hwmon: (applesmc) Extract all features generically
With temperature keys being determined automatically, the dmi match
data is only used to assign features that can easily be detected from
the smc. This patch removes the dmi match data altogether, and reduces
the match table to the main machine models.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Henrik Rydberg [Wed, 10 Nov 2010 10:58:04 +0000 (10:58 +0000)]
hwmon: (applesmc) Dynamic creation of temperature files
The current driver creates temperature files based on a list
of temperature keys given per device. Apart from slow adaption
to new machine models, the number of sensors also depends on
the number of processors. This patch looks up the temperature
keys dynamically, thereby supporting all models.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Henrik Rydberg [Wed, 10 Nov 2010 10:58:03 +0000 (10:58 +0000)]
hwmon: (applesmc) Introduce a register lookup table
One main problem with the current driver is the inability to quickly
search for supported keys, resulting in detailed feature maps per
machine model which are cumbersome to maintain.
This patch adds a register lookup table, which enables binary search
for supported keys. The lookup also reduces the io frequency, so the
original mutex is replaced by locks around the actual io.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
[guenter.roeck@ericsson.com: Added value range check to key_at_index_store()] Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Henrik Rydberg [Tue, 9 Nov 2010 15:15:02 +0000 (15:15 +0000)]
hwmon: (applesmc) Relax the severity of device init failure
The device init is used to reset the accelerometer. Failure to reset
is not severe enough to stop loading the module or to resume from
hibernation. This patch relaxes failure to a warning and drops
output in case of success.
Cc: stable@kernel.org Signed-off-by: Henrik Rydberg <rydberg@euromail.se> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Joe Perches [Wed, 20 Oct 2010 06:51:26 +0000 (06:51 +0000)]
hwmon: (abituguru3) Use pr_fmt and pr_<level>
Added #define pr_fmt KBUILD_MODNAME ": " fmt
Converted printks to pr_<level>
Coalesced any long formats
Removed prefixes from formats
Added a few static strings to standardize logging messages.
Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Joe Perches [Wed, 20 Oct 2010 06:51:25 +0000 (06:51 +0000)]
hwmon: (abituguru) Use pr_fmt and pr_<level>
Added #define pr_fmt KBUILD_MODNAME ": " fmt
Converted printks to pr_<level>
Coalesced any long formats
Removed prefixes from formats
Added a few static strings to standardize logging messages.
Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Linus Torvalds [Sat, 8 Jan 2011 01:16:27 +0000 (17:16 -0800)]
Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/hfsplus
* 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/hch/hfsplus:
hfsplus: %L-to-%ll, macro correction, and remove unneeded braces
hfsplus: spaces/indentation clean-up
hfsplus: C99 comments clean-up
hfsplus: over 80 character lines clean-up
hfsplus: fix an artifact in ioctl flag checking
hfsplus: flush disk caches in sync and fsync
hfsplus: optimize fsync
hfsplus: split up inode flags
hfsplus: write up fsync for directories
hfsplus: simplify fsync
hfsplus: avoid useless work in hfsplus_sync_fs
hfsplus: make sure sync writes out all metadata
hfsplus: use raw bio access for partition tables
hfsplus: use raw bio access for the volume headers
hfsplus: always use hfsplus_sync_fs to write the volume header
hfsplus: silence a few debug printks
hfsplus: fix option parsing during remount
Fix up conflicts due to VFS changes in fs/hfsplus/{hfsplus_fs.h,unicode.c}
Linus Torvalds [Sat, 8 Jan 2011 01:08:46 +0000 (17:08 -0800)]
Merge branch 'next-spi' of git://git.secretlab.ca/git/linux-2.6
* 'next-spi' of git://git.secretlab.ca/git/linux-2.6: (77 commits)
spi/omap: Fix DMA API usage in OMAP MCSPI driver
spi/imx: correct the test on platform_get_irq() return value
spi/topcliff: Typo fix threhold to threshold
spi/dw_spi Typo change diable to disable.
spi/fsl_espi: change the read behaviour of the SPIRF
spi/mpc52xx-psc-spi: move probe/remove to proper sections
spi/dw_spi: add DMA support
spi/dw_spi: change to EXPORT_SYMBOL_GPL for exported APIs
spi/dw_spi: Fix too short timeout in spi polling loop
spi/pl022: convert running variable
spi/pl022: convert busy flag to a bool
spi/pl022: pass the returned sglen to the DMA engine
spi/pl022: map the buffers on the DMA engine
spi/topcliff_pch: Fix data transfer issue
spi/imx: remove autodetection
spi/pxa2xx: pass of_node to spi device and set a parent device
spi/pxa2xx: Modify RX-Tresh instead of busy-loop for the remaining RX bytes.
spi/pxa2xx: Add chipselect support for Sodaville
spi/pxa2xx: Consider CE4100's FIFO depth
spi/pxa2xx: Add CE4100 support
...
Linus Torvalds [Sat, 8 Jan 2011 01:02:58 +0000 (17:02 -0800)]
Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits)
gameport: use this_cpu_read instead of lookup
x86: udelay: Use this_cpu_read to avoid address calculation
x86: Use this_cpu_inc_return for nmi counter
x86: Replace uses of current_cpu_data with this_cpu ops
x86: Use this_cpu_ops to optimize code
vmstat: User per cpu atomics to avoid interrupt disable / enable
irq_work: Use per cpu atomics instead of regular atomics
cpuops: Use cmpxchg for xchg to avoid lock semantics
x86: this_cpu_cmpxchg and this_cpu_xchg operations
percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support
percpu,x86: relocate this_cpu_add_return() and friends
connector: Use this_cpu operations
xen: Use this_cpu_inc_return
taskstats: Use this_cpu_ops
random: Use this_cpu_inc_return
fs: Use this_cpu_inc_return in buffer.c
highmem: Use this_cpu_xx_return() operations
vmstat: Use this_cpu_inc_return for vm statistics
x86: Support for this_cpu_add, sub, dec, inc_return
percpu: Generic support for this_cpu_add, sub, dec, inc_return
...
Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c}
as per Tejun.
Linus Torvalds [Sat, 8 Jan 2011 00:58:04 +0000 (16:58 -0800)]
Merge branch 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (33 commits)
usb: don't use flush_scheduled_work()
speedtch: don't abuse struct delayed_work
media/video: don't use flush_scheduled_work()
media/video: explicitly flush request_module work
ioc4: use static work_struct for ioc4_load_modules()
init: don't call flush_scheduled_work() from do_initcalls()
s390: don't use flush_scheduled_work()
rtc: don't use flush_scheduled_work()
mmc: update workqueue usages
mfd: update workqueue usages
dvb: don't use flush_scheduled_work()
leds-wm8350: don't use flush_scheduled_work()
mISDN: don't use flush_scheduled_work()
macintosh/ams: don't use flush_scheduled_work()
vmwgfx: don't use flush_scheduled_work()
tpm: don't use flush_scheduled_work()
sonypi: don't use flush_scheduled_work()
hvsi: don't use flush_scheduled_work()
xen: don't use flush_scheduled_work()
gdrom: don't use flush_scheduled_work()
...
Fixed up trivial conflict in drivers/media/video/bt8xx/bttv-input.c
as per Tejun.
Linus Torvalds [Fri, 7 Jan 2011 22:55:48 +0000 (14:55 -0800)]
Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Constify function scope static struct sched_param usage
sched: Fix strncmp operation
sched: Move sched_autogroup_exit() to free_signal_struct()
sched: Fix struct autogroup memory leak
sched: Mark autogroup_init() __init
sched: Consolidate the name of root_task_group and init_task_group
Linus Torvalds [Fri, 7 Jan 2011 22:55:31 +0000 (14:55 -0800)]
Merge branch 'x86-apic-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-apic-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: apic: Cleanup and simplify setup_local_APIC()
x86: Further simplify mp_irq info handling
x86: Unify 3 similar ways of saving mp_irqs info
x86, ioapic: Avoid writing io_apic id if already correct
x86, x2apic: Don't map lapic addr for preenabled x2apic systems
x86, sfi: Use register_lapic_address()
x86, apic: Use register_lapic_address() in init_apic_mapping()
x86, apic: Remove early_init_lapic_mapping()
x86, apic: Unify identical register_lapic_address() functions
Linus Torvalds [Fri, 7 Jan 2011 22:50:14 +0000 (14:50 -0800)]
Merge branch 'rmobile-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6
* 'rmobile-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6: (67 commits)
ARM: mach-shmobile: update for SMP changes.
ARM: mach-shmobile: update for GIC changes.
ARM: mach-shmobile: Fix up clkdev fallout for SH73A0.
dma: shdma: don't register the global die notifier multiple times
ARM: mach-shmobile: Rely on run-time IRQ handlers
ARM: mach-shmobile: Run-time IRQ handler for GIC
ARM: mach-shmobile: Run-time IRQ handler for INTCA
ARM: mach-shmobile: Enable CONFIG_MULTI_IRQ_HANDLER
ARM: mach-shmobile: Use shared GIC entry macros
ARM: mach-shmobile: mackerel: Add zboot support
ARM: mach-shmobile: mackerel: Add HDMI sound support
ARM: mach-shmobile: mackerel: add HDMI video support
ARM: mach-shmobile: ap4evb: fixup clk_put timing of fsib_clk
ARM: mach-shmobile: sh73a0: fix div4 table
ARM: mach-shmobile: ap4/mackerel: modify wrong comment out of USB
ARM: mach-shmobile: Mackerel VGA camera support
mmc: sh_mmcif: make DMA support by the driver unconditional
ARM: mach-shmobile: Add eMMC support through MMCIF on AG5EVM
ARM: mach-shmobile: Use pullups for AG5EVM KEYSC pins
ARM: mach-shmobile: sh73a0 GPIO pullup improvement
...
Linus Torvalds [Fri, 7 Jan 2011 22:45:47 +0000 (14:45 -0800)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input: (58 commits)
Input: wacom_w8001 - support pen or touch only devices
Input: wacom_w8001 - use __set_bit to set keybits
Input: bu21013_ts - fix misuse of logical operation in place of bitop
Input: i8042 - add Acer Aspire 5100 to the Dritek list
Input: wacom - add support for digitizer in Lenovo W700
Input: psmouse - disable the synaptics extension on OLPC machines
Input: psmouse - fix up Synaptics comment
Input: synaptics - ignore bogus mt packet
Input: synaptics - add multi-finger and semi-mt support
Input: synaptics - report clickpad property
input: mt: Document interface updates
Input: fix double equality sign in uevent
Input: introduce device properties
hid: egalax: Add support for Wetab (726b)
Input: include MT library as source for kerneldoc
MAINTAINERS: Update input-mt entry
hid: egalax: Add support for Samsung NB30 netbook
hid: egalax: Document the new devices in Kconfig
hid: egalax: Add support for Wetab
hid: egalax: Convert to MT slots
...
Fixed up trivial conflict in drivers/input/keyboard/Kconfig
Linus Torvalds [Fri, 7 Jan 2011 21:16:28 +0000 (13:16 -0800)]
Merge branch 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6
* 'usb-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (144 commits)
USB: add support for Dream Cheeky DL100B Webmail Notifier (1d34:0004)
USB: serial: ftdi_sio: add support for TIOCSERGETLSR
USB: ehci-mxc: Setup portsc register prior to accessing OTG viewport
USB: atmel_usba_udc: fix freeing irq in usba_udc_remove()
usb: ehci-omap: fix tll channel enable mask
usb: ohci-omap3: fix trivial typo
USB: gadget: ci13xxx: don't assume that PAGE_SIZE is 4096
USB: gadget: ci13xxx: fix complete() callback for no_interrupt rq's
USB: gadget: update ci13xxx to work with g_ether
USB: gadgets: ci13xxx: fix probing of compiled-in gadget drivers
Revert "USB: musb: pm: don't rely fully on clock support"
Revert "USB: musb: blackfin: pm: make it work"
USB: uas: Use GFP_NOIO instead of GFP_KERNEL in I/O submission path
USB: uas: Ensure we only bind to a UAS interface
USB: uas: Rename sense pipe and sense urb to status pipe and status urb
USB: uas: Use kzalloc instead of kmalloc
USB: uas: Fix up the Sense IU
usb: musb: core: kill unneeded #include's
DA8xx: assign name to MUSB IRQ resource
usb: gadget: g_ncm added
...
Manually fix up trivial conflicts in USB Kconfig changes in:
arch/arm/mach-omap2/Kconfig
arch/sh/Kconfig
drivers/usb/Kconfig
drivers/usb/host/ehci-hcd.c
and annoying chip clock data conflicts in:
arch/arm/mach-omap2/clock3xxx_data.c
arch/arm/mach-omap2/clock44xx_data.c
* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (147 commits)
[SCSI] arcmsr: fix write to device check
[SCSI] lpfc: lower stack use in lpfc_fc_frame_check
[SCSI] eliminate an unnecessary local variable from scsi_remove_target()
[SCSI] libiscsi: use bh locking instead of irq with session lock
[SCSI] libiscsi: do not take host lock in queuecommand
[SCSI] be2iscsi: fix null ptr when accessing task hdr
[SCSI] be2iscsi: fix gfp use in alloc_pdu
[SCSI] libiscsi: add more informative failure message during iscsi scsi eh
[SCSI] gdth: Add missing call to gdth_ioctl_free
[SCSI] bfa: remove unused defintions and misc cleanups
[SCSI] bfa: remove inactive functions
[SCSI] bfa: replace bfa_assert with WARN_ON
[SCSI] qla2xxx: Use sg_next to fetch next sg element while walking sg list.
[SCSI] qla2xxx: Fix to avoid recursive lock failure during BSG timeout.
[SCSI] qla2xxx: Remove code to not reset ISP82xx on failure.
[SCSI] qla2xxx: Display mailbox register 4 during 8012 AEN for ISP82XX parts.
[SCSI] qla2xxx: Don't perform a BIG_HAMMER if Get-ID (0x20) mailbox command fails on CNAs.
[SCSI] qla2xxx: Remove redundant module parameter permission bits
[SCSI] qla2xxx: Add sysfs node for displaying board temperature.
[SCSI] qla2xxx: Code cleanup to remove unwanted comments and code.
...
Running the latest kernel on the 4430SDP board with DMA API debugging
enabled results in this:
WARNING: at lib/dma-debug.c:803 check_unmap+0x19c/0x6f0()
NULL NULL: DMA-API: device driver tries to free DMA memory it has not allocated
[device address=0x000000008129901a] [size=260 bytes]
Modules linked in:
Backtrace:
[<c003cbe0>] (dump_backtrace+0x0/0x10c) from [<c0278da8>] (dump_stack+0x18/0x1c)
r7:c1839dc0 r6:c0198578 r5:c0304b17 r4:00000323
[<c0278d90>] (dump_stack+0x0/0x1c) from [<c005b158>] (warn_slowpath_common+0x58/0x70)
[<c005b100>] (warn_slowpath_common+0x0/0x70) from [<c005b214>] (warn_slowpath_fmt+0x38/0x40)
r8:c1839e40 r7:00000000 r6:00000104 r5:00000000 r4:8129901a
[<c005b1dc>] (warn_slowpath_fmt+0x0/0x40) from [<c0198578>] (check_unmap+0x19c/0x6f0)
r3:c03110de r2:c0304e6b
[<c01983dc>] (check_unmap+0x0/0x6f0) from [<c0198cd8>] (debug_dma_unmap_page+0x74/0x80)
[<c0198c64>] (debug_dma_unmap_page+0x0/0x80) from [<c01d5ad8>] (omap2_mcspi_work+0x514/0xbf0)
[<c01d55c4>] (omap2_mcspi_work+0x0/0xbf0) from [<c006dfb0>] (process_one_work+0x294/0x400)
[<c006dd1c>] (process_one_work+0x0/0x400) from [<c006e50c>] (worker_thread+0x220/0x3f8)
[<c006e2ec>] (worker_thread+0x0/0x3f8) from [<c00738d0>] (kthread+0x88/0x90)
[<c0073848>] (kthread+0x0/0x90) from [<c005e924>] (do_exit+0x0/0x5fc)
r7:00000013 r6:c005e924 r5:c0073848 r4:c1829ee0
---[ end trace 1b75b31a2719ed20 ]---
I've no idea why this driver uses NULL for dma_unmap_single instead of
the &spi->dev that is laying around just waiting to be used in that
function - but it's an easy fix.
Also replace this comment with a FIXME comment:
/* Do DMA mapping "early" for better error reporting and
* dcache use. Note that if dma_unmap_single() ever starts
* to do real work on ARM, we'd need to clean up mappings
* for previous transfers on *ALL* exits of this loop...
*/
as the comment is not true - we do work in dma_unmap() functions,
particularly on ARMv6 and above. I've corrected the existing unmap
functions but if any others are required they must be added ASAP.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Richard Genoud [Fri, 7 Jan 2011 14:26:01 +0000 (15:26 +0100)]
spi/imx: correct the test on platform_get_irq() return value
The test "if (spi_imx->irq <= 0)" is not testing the IRQ value, but
the return value of platform_get_irq(). As platform_get_irq() can
return an error (-ENXIO) or the IRQ value it found, the test should be
"if (spi_imx->irq < 0)"
[grant.likely: Note: In general, Linux irq number 0 should also mean
no irq, but arm still allows devices to be assigned 0, and the imx
platform uses 0 for one of the spi devices, so this patch is needed
for the device to work]
Signed-off-by: Richard Genoud <richard.genoud@gmail.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Hillf Danton [Thu, 6 Jan 2011 12:58:12 +0000 (20:58 +0800)]
sched: Fix strncmp operation
One of the operands, buf, is incorrect, since it is stripped and the
correct address for subsequent string comparing could change if
leading white spaces, if any, are removed from buf.
Yong Zhang [Fri, 7 Jan 2011 07:17:36 +0000 (15:17 +0800)]
sched: Consolidate the name of root_task_group and init_task_group
root_task_group is the leftover of USER_SCHED, now it's always
same to init_task_group.
But as Mike suggested, root_task_group is maybe the suitable name
to keep for a tree.
So in this patch:
init_task_group --> root_task_group
init_task_group_load --> root_task_group_load
INIT_TASK_GROUP_LOAD --> ROOT_TASK_GROUP_LOAD
Suggested-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110107071736.GA32635@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Borislav Petkov [Wed, 24 Nov 2010 18:52:09 +0000 (19:52 +0100)]
EDAC: Fixup scrubrate manipulation
Make the ->{get|set}_sdram_scrub_rate return the actual scrub rate
bandwidth it succeeded setting and remove superfluous arg pointer used
for that. A negative value returned still means that an error occurred
while setting the scrubrate. Document this for future reference.
Borislav Petkov [Fri, 1 Oct 2010 17:35:38 +0000 (19:35 +0200)]
amd64_edac: Concentrate per-family init even more
Move the remaining per-family init code into the proper place and
simplify the rest of the initialization. Reorganize error handling in
amd64_init_one_instance().
Borislav Petkov [Fri, 1 Oct 2010 16:38:19 +0000 (18:38 +0200)]
amd64_edac: Add per-family init function
Run a per-family init function which does all the settings based on
the family this driver instance is running on. Move the scrubrate
calculation in it and simplify code.
Nick Piggin [Fri, 7 Jan 2011 06:50:11 +0000 (17:50 +1100)]
fs: scale mntget/mntput
The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.
The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.
We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.
- check the global sum once every interval (this will delay zero detection
for some interval, so it's probably a showstopper for vfsmounts).
- keep a local count and only taking the global sum when local reaches 0 (this
is difficult for vfsmounts, because we can't hold preempt off for the life of
a reference, so a counter would need to be per-thread or tied strongly to a
particular CPU which requires more locking).
- keep a local difference of increments and decrements, which allows us to sum
the total difference and hence find the refcount when summing all CPUs. Then,
keep a single integer "long" refcount for slow and long lasting references,
and only take the global sum of local counters when the long refcount is 0.
This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.
This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.
This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.