NeilBrown [Thu, 13 Aug 2009 00:06:24 +0000 (10:06 +1000)]
md/raid5: allow new reshape modes to be restarted in the middle.
md/raid5 doesn't allow a reshape to restart if it involves writing
over the same part of disk that it would be reading from.
This happens at the beginning of a reshape that increases the number
of devices, at the end of a reshape that decreases the number of
devices, and continuously for a reshape that does not change the
number of devices.
The current code is correct for the "increase number of devices"
case as the critical section at the start is handled by userspace
performing a backup.
It does not work for reducing the number of devices, or the
no-change case.
For 'reducing', we need to invert the test. For no-change we cannot
really be sure things will be safe, so simply require the array
to be read-only, which is how the user-space code which carefully
starts such arrays works.
NeilBrown [Wed, 12 Aug 2009 23:54:02 +0000 (09:54 +1000)]
md: never advance 'events' counter by more than 1.
When assembling arrays, md allows two devices to have different event
counts as long as the difference is only '1'. This is to cope with
a system failure between updating the metadata on two difference
devices.
However there are currently times when we update the event count by
2. This was done to keep the event count even when the array is clean
and odd when it is dirty, which allows us to avoid writing common
update to spare devices and so allow those spares to go to sleep.
This is bad for the above reason. So change it to never increase by
two. This means that the alignment between 'odd/even' and
'clean/dirty' might take a little longer to attain, but that is only a
small cost. The spares will get a few more updates but that will
still be spared (;-) most updates and can still go to sleep.
Prior to this patch there was a small chance that after a crash an
array would fail to assemble due to the overly large event count
mismatch.
introduced the possibility of an A-B/B-A deadlock between
bd_mutex and reconfig_mutex.
__blkdev_get holds bd_mutex while calling md_open which takes
reconfig_mutex,
do_md_run is always called with reconfig_mutex held, and it now
takes bd_mutex in the call the revalidate_disk.
This potential deadlock was not caught by lockdep due to the
use of mutex_lock_interruptible_nexted which was introduced
by
commit d63a5a74dee87883fda6b7d170244acaac5b05e8
do avoid a warning of an impossible deadlock.
It is quite possible to split reconfig_mutex in to two locks.
One protects the array data structures while it is being
reconfigured, the other ensures that an array is never even partially
open while it is being deactivated.
In particular, the second lock prevents an open from completing
between the time when do_md_stop checks if there are any active opens,
and the time when the array is either set read-only, or when ->pers is
set to NULL. So we can be certain that no IO is in flight as the
array is being destroyed.
So create a new lock, open_mutex, just to ensure exclusion between
'open' and 'stop'.
This avoids the deadlock and also avoids the lockdep warning mentioned
in commit d63a5a74d
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6:
USB: fix oops on disconnect in cdc-acm
USB: storage: include Prolific Technology USB drive in unusual_devs list
USB: ftdi_sio: add product_id for Marvell OpenRD Base, Client
USB: ftdi_sio: add vendor and product id for Bayer glucose meter serial converter cable
USB: EHCI: fix counting of transaction error retries
USB: EHCI: fix two new bugs related to Clear-TT-Buffer
USB: usbfs: fix -ENOENT error code to be -ENODEV
USB: musb: fix the nop registration for OMAP3EVM
USB: devio: Properly do access_ok() checks
USB: pl2303: New vendor and product id
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging-2.6:
Staging: rspiusb: Fix buffer overflow
staging: add dependencies on PCI for drivers that require it
Staging: rtl8192su: fix build error
Staging: rt2870: Revert d44ca7 Removal of kernel_thread() API
Staging: rt2870: Add USB ID for Linksys, Planex Communications, Belkin
Linus Torvalds [Sat, 8 Aug 2009 02:03:59 +0000 (19:03 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt/drm-intel
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt/drm-intel: (22 commits)
drm/i915: Fix read outside array bounds in restoring the SWF10 range.
drm/i915: Use our own workqueue to avoid wedging the system along with the GPU.
drm/i915: Add support for dual-channel LVDS on 8xx.
drm/i915: Return disconnected for SDVO DVI when there's no digital EDID.
drm/i915: Choose real sdvo output according to result from detection
drm/i915: Set preferred mode for integrated TV according to TV format
drm/i915: fix 845G FIFO size & burst length
drm/i915: fix VGA detect on IGDNG
drm/i915: Add eDP support on IGDNG mobile chip
drm/i915: enable DisplayPort support on IGDNG
drm/i915: Fix channel ending action for DP aux transaction
drm/i915: fix issue in display pipe setup on IGDNG
drm/i915: disable VGA plane reliably
drm/I915: Fix offset to DVO timings in LVDS data
drm/i915: hdmi detection according by reading edid
drm/i915: correct self-refresh calculation in "everything off" case
drm/i915: handle FIFO oversubsription correctly
drm/i915: FIFO watermark calculation fixes
drm/i915: ignore lvds on AOpen Mini PC MP-915
drm/i915: Allow frame buffers up to 4096x4096 on 915/945 class hardware
...
This fixes a build error when selecting the rtl8192su driver as a
module. This has been reported by me, and the opensuse kernel developer
team, and I finally tracked it down.
Oliver Neukum [Tue, 4 Aug 2009 21:52:09 +0000 (23:52 +0200)]
USB: fix oops on disconnect in cdc-acm
This patch fixes an oops caused when during an unplug a device's table
of endpoints is zeroed before the driver is notified. A pointer to
the endpoint must be cached.
Marko Hänninen [Fri, 31 Jul 2009 19:32:39 +0000 (22:32 +0300)]
USB: ftdi_sio: add vendor and product id for Bayer glucose meter serial converter cable
Attached patch adds USB vendor and product IDs for Bayer's USB to serial
converter cable used by Bayer blood glucose meters. It seems to be a
FT232RL based device and works without any problem with ftdi_sio driver
when this patch is applied. See: http://winglucofacts.com/cables/
Alan Stern [Fri, 31 Jul 2009 14:41:40 +0000 (10:41 -0400)]
USB: EHCI: fix counting of transaction error retries
This patch (as1274) simplifies the counting of transaction-error
retries. Now we will count up from 0 to QH_XACTERR_MAX instead of
down from QH_XACTERR_MAX to 0.
The patch also fixes a small bug: qh->xacterr was not getting
initialized for interrupt endpoints.
Alan Stern [Fri, 31 Jul 2009 14:40:22 +0000 (10:40 -0400)]
USB: EHCI: fix two new bugs related to Clear-TT-Buffer
This patch (as1273) fixes two(!) bugs introduced by the new
Clear-TT-Buffer implementation in ehci-hcd.
It is now possible for an idle QH to have some URBs on its
queue -- this will happen if a Clear-TT-Buffer is pending for
the QH's endpoint. Consequently we should not issue a warning
when someone tries to unlink an URB from an idle QH; instead
we should process the request immediately.
The refcounts for QHs could get messed up, because
submit_async() would increment the refcount when calling
qh_link_async() and qh_link_async() would then refuse to link
the QH into the schedule if a Clear-TT-Buffer was pending.
Instead we should increment the refcount only when the QH
actually is added to the schedule. The current code tries to
be clever by leaving the refcount alone if an unlink is
immediately followed by a relink; the patch changes this to an
unconditional decrement and increment (although they occur in
the opposite order).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: David Brownell <david-b@pacbell.net> Tested-by: Manuel Lauss <manuel.lauss@gmail.com> Tested-by: Matthijs Kooijman <matthijs@stdin.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Alan Stern [Thu, 30 Jul 2009 19:28:14 +0000 (15:28 -0400)]
USB: usbfs: fix -ENOENT error code to be -ENODEV
This patch (as1272) changes the error code returned when an open call
for a USB device node fails to locate the corresponding device. The
appropriate error code is -ENODEV, not -ENOENT.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Kay Sievers <kay.sievers@vrfy.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Michael Buesch [Wed, 29 Jul 2009 09:39:03 +0000 (11:39 +0200)]
USB: devio: Properly do access_ok() checks
access_ok() checks must be done on every part of the userspace structure
that is accessed. If access_ok() on one part of the struct succeeded, it
does not imply it will succeed on other parts of the struct. (Does
depend on the architecture implementation of access_ok()).
This changes the __get_user() users to first check access_ok() on the
data structure.
Signed-off-by: Michael Buesch <mb@bu3sch.de> Cc: stable <stable@kernel.org> Cc: Pete Zaitcev <zaitcev@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
I am submitting a patch for the pl2303 driver. This patch adds support
for the "Sony QN-3USB" cable (vendor=0x054c, product=0x0437). This USB
cable is a so-called data cable used to connect a Sony mobile phone to a
computer. Supported models are Sony CMD-J5, J6, J7, J16, J26, J70 and
Z7.
I have used this patch with my Sony CMD-J70 for several days and I
haven't encountered any kernel/hardware issue.
Yan Zheng [Fri, 7 Aug 2009 17:51:33 +0000 (13:51 -0400)]
Btrfs: fix balancing oops when invalidate_inode_pages2 returns EBUSY
invalidate_inode_pages2_range may return -EBUSY occasionally
which results Oops. This patch fixes the issue by moving
invalidate_inode_pages2_range into a loop and keeping calling
it until the return value is not -EBUSY.
The EBUSY return is temporary, and can happen when the btrfs release page
function is unable to release a page because the EXTENT_LOCK
bit is set.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
Linus Torvalds [Fri, 7 Aug 2009 17:43:07 +0000 (10:43 -0700)]
Merge branch 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf_counter: Fix double list iteration in per task precise stats
perf: Auto-detect libelf
perf symbol: Fix symbol parsing in certain cases: use the build-id as a symlink
perf_counter/powerpc: Check oprofile_cpu_type for NULL before using it
ftrace: Fix perf-tracepoint OOPS
perf report: Add missing command line options to man page
perf: Auto-detect libbfd
perf report: Make --sort comm,dso,symbol the default
Linus Torvalds [Fri, 7 Aug 2009 17:42:31 +0000 (10:42 -0700)]
Merge git://git.infradead.org/mtd-2.6
* git://git.infradead.org/mtd-2.6:
jffs2: Fix return value from jffs2_do_readpage_nolock()
mtd: mtdblock: introduce mtdblks_lock
mtd: remove 'SBC8240 Wind River' Device Driver Code
mtd: OneNAND: OMAP2/3: free GPMC CS on module removal
mtd: OneNAND: fix incorrect bufferram offset
mtd: blkdevs: do not forget to get MTD devices
mtd: fix the conversion from dev to mtd_info
mtd: let include/linux/mtd/partitions.h stand on its own
Linus Torvalds [Fri, 7 Aug 2009 17:41:36 +0000 (10:41 -0700)]
Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6:
drm/radeon/kms: setup MC/VRAM the same way for suspend/resume
drm/radeon/kms: Fix caching mode selection for GTT object
Albin Tonnerre [Thu, 6 Aug 2009 22:09:32 +0000 (15:09 -0700)]
lib/decompress_*: only include <linux/slab.h> if STATIC is not defined
These includes were added by 079effb6933f34b9b1b67b08bd4fd7fb672d16ef
("kmemtrace, kbuild: fix slab.h dependency problem in
lib/decompress_inflate.c") to fix the build when using kmemtrace. However
this is not necessary when used to create a compressed kernel, and
actually creates issues (brings a lot of things unavailable in the
decompression environment), so don't include it if STATIC is defined.
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Phillip Lougher <phillip@lougher.demon.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Phillip Lougher [Thu, 6 Aug 2009 22:09:31 +0000 (15:09 -0700)]
bzip2/lzma: remove nasty uncompressed size hack in pre-boot environment
decompress_bunzip2 and decompress_unlzma have a nasty hack that subtracts
4 from the input length if being called in the pre-boot environment.
This is a nasty hack because it relies on the fact that flush = NULL only
when called from the pre-boot environment (i.e.
arch/x86/boot/compressed/misc.c). initramfs.c/do_mounts_rd.c pass in a
flush buffer (flush != NULL).
This hack prevents the decompressors from being used with flush = NULL by
other callers unless knowledge of the hack is propagated to them.
This patch removes the hack by making decompress (called only from the
pre-boot environment) a wrapper function that subtracts 4 from the input
length before calling the decompressor.
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Phillip Lougher [Thu, 6 Aug 2009 22:09:30 +0000 (15:09 -0700)]
bzip2/lzma/gzip: fix comments describing decompressor API
Fix and improve comments in decompress/generic.h that describe the
decompressor API. Also remove an unused definition, and rename INBUF_LEN
in lib/decompress_inflate.c to conform to bzip2/lzma naming.
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Dumazet [Thu, 6 Aug 2009 22:09:28 +0000 (15:09 -0700)]
execve: must clear current->clear_child_tid
While looking at Jens Rosenboom bug report
(http://lkml.org/lkml/2009/7/27/35) about strange sys_futex call done from
a dying "ps" program, we found following problem.
clone() syscall has special support for TID of created threads. This
support includes two features.
One (CLONE_CHILD_SETTID) is to set an integer into user memory with the
TID value.
One (CLONE_CHILD_CLEARTID) is to clear this same integer once the created
thread dies.
The integer location is a user provided pointer, provided at clone()
time.
kernel keeps this pointer value into current->clear_child_tid.
At execve() time, we should make sure kernel doesnt keep this user
provided pointer, as full user memory is replaced by a new one.
As glibc fork() actually uses clone() syscall with CLONE_CHILD_SETTID and
CLONE_CHILD_CLEARTID set, chances are high that we might corrupt user
memory in forked processes.
Following sequence could happen:
1) bash (or any program) starts a new process, by a fork() call that
glibc maps to a clone( ... CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID
...) syscall
2) When new process starts, its current->clear_child_tid is set to a
location that has a meaning only in bash (or initial program) context
(&THREAD_SELF->tid)
3) This new process does the execve() syscall to start a new program.
current->clear_child_tid is left unchanged (a non NULL value)
4) If this new program creates some threads, and initial thread exits,
kernel will attempt to clear the integer pointed by
current->clear_child_tid from mm_release() :
/*
* We don't check the error code - if userspace has
* not set up a proper pointer then tough luck.
*/
<< here >> put_user(0, tidptr);
sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
}
5) OR : if new program is not multi-threaded, but spied by /proc/pid
users (ps command for example), mm_users > 1, and the exiting program
could corrupt 4 bytes in a persistent memory area (shm or memory mapped
file)
If current->clear_child_tid points to a writeable portion of memory of the
new program, kernel happily and silently corrupts 4 bytes of memory, with
unexpected effects.
Fix is straightforward and should not break any sane program.
x = sdhci_alloc_host(...)
... when != x = E
(
* if (x == NULL || ...) S1 else S2
|
* if (x == NULL && ...) S1 else S2
)
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk> Acked-by: Anton Vorontsov <avorontsov@ru.mvista.com> Cc: Matt Fleming <matt@console-pimps.org> Cc: Ian Molton <ian@mnementh.co.uk> Cc: "Roberto A. Foglietta" <roberto.foglietta@gmail.com> Cc: Philip Langdale <philipl@overt.org> Cc: Pierre Ossman <pierre@ossman.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recent framebuffer locking patches first made affected systems unbootable,
then the dead-lock has been fixed but as of 2.6.31-rc4 the framebuffer on
mx3 machines doesn't work. Fix this.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
OGAWA Hirofumi [Thu, 6 Aug 2009 22:07:39 +0000 (15:07 -0700)]
vfs: mnt_want_write_file(): fix special file handling
I suspect that mnt_want_write_file() may have wrong assumption. I think
mnt_want_write_file() is assuming it increments ->mnt_writers if
(file->f_mode & FMODE_WRITE). But, if it's special_file(), it is false?
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Acked-by: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Sandeen [Thu, 6 Aug 2009 22:07:37 +0000 (15:07 -0700)]
compat_ioctl: hook up compat handler for FIEMAP ioctl
The FIEMAP_IOC_FIEMAP mapping ioctl was missing a 32-bit compat handler,
which means that 32-bit suerspace on 64-bit kernels cannot use this ioctl
command.
The structure is nicely aligned, padded, and sized, so it is just this
simple.
Tested w/ 32-bit ioctl tester (from Josef) on a 64-bit kernel on ext4.
Signed-off-by: Eric Sandeen <sandeen@redhat.com> Cc: <linux-ext4@vger.kernel.org> Cc: Mark Lord <lkml@rtr.ca> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Josef Bacik <josef@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The common way for the VC drivers is to set the screen dimension
parameters manually in the init case and only call vc_resize() for
!init - which allocates a screen buffer according to the new
dimensions.
fbcon instead would do vc_resize() unconditionally and afterwards set
the dimensions manually (again) for !init - i.e. completely upside
down. The vc_resize() allocated buffer would then get lost by
vc_allocate() allocating a fresh one.
Use vc_resize() only for actual resizing to close the leak.
Set the dimensions manually only in initialization mode to remove the
redundant setting in resize mode.
Reported-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Tested-by: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This fixes a bug caused by changing pointers (viafb_mode, viafb_mode1)
assigned by module_param. It reduces driver complexity by not needlessly
changing these vars as they are only read once and removing now
superfluous code.
On unpatched kernels loading viafb with viafb_mode or viafb_mode1 option
used and afterwards unloading it results in:
This is caused by the current code changing the pointers assigned by
module_param. During unload it tries to free the memory the pointers
point at which is now part of an internal structure.
The patch simply avoids changing the pointers. This is okay as they are
read only once during the initialization process.
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de> Cc: Scott Fang <ScottFang@viatech.com.cn> Cc: Joseph Chan <JosephChan@via.com.tw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: make set_mempolicy(MPOL_INTERLEAV) N_HIGH_MEMORY aware
At first, init_task's mems_allowed is initialized as this.
init_task->mems_allowed == node_state[N_POSSIBLE]
And cpuset's top_cpuset mask is initialized as this
top_cpuset->mems_allowed = node_state[N_HIGH_MEMORY]
Before 2.6.29:
policy's mems_allowed is initialized as this.
1. update tasks->mems_allowed by its cpuset->mems_allowed.
2. policy->mems_allowed = nodes_and(tasks->mems_allowed, user's mask)
Updating task's mems_allowed in reference to top_cpuset's one.
cpuset's mems_allowed is aware of N_HIGH_MEMORY, always.
In 2.6.30: After commit 58568d2a8215cb6f55caf2332017d7bdff954e1c
("cpuset,mm: update tasks' mems_allowed in time"), policy's mems_allowed
is initialized as this.
Then, policy's mems_allowd can includes a possible node, which has no pgdat.
MPOL's INTERLEAVE just scans nodemask of task->mems_allowd and access this
directly.
NODE_DATA(nid)->zonelist even if NODE_DATA(nid)==NULL
Then, what's we need is making policy->mems_allowed be aware of
N_HIGH_MEMORY. This patch does that. But to do so, extra nodemask will
be on statck. Because I know cpumask has a new interface of
CPUMASK_ALLOC(), I added it to node.
This patch stands on old behavior. But I feel this fix itself is just a
Band-Aid. But to do fundametal fix, we have to take care of memory
hotplug and it takes time. (task->mems_allowd should be N_HIGH_MEMORY, I
think.)
mpol_set_nodemask() should be aware of N_HIGH_MEMORY and policy's nodemask
should be includes only online nodes.
In old behavior, this is guaranteed by frequent reference to cpuset's
code. Now, most of them are removed and mempolicy has to check it by
itself.
To do check, a few nodemask_t will be used for calculating nodemask. But,
size of nodemask_t can be big and it's not good to allocate them on stack.
Now, cpumask_t has CPUMASK_ALLOC/FREE an easy code for get scratch area.
NODEMASK_ALLOC/FREE shoudl be there.
[akpm@linux-foundation.org: cleanups & tweaks] Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Miao Xie <miaox@cn.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: Paul Menage <menage@google.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Yasunori Goto <y-goto@jp.fujitsu.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: David Rientjes <rientjes@google.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stefani Seibold [Thu, 6 Aug 2009 22:07:30 +0000 (15:07 -0700)]
fbcon: fix rotate upside down crash
Fix the rotate_ud() function not to crash in case of a font which has not
a width of multiple by 8: The inner loop of the font pixel copy should not
access a bit outside the font memory area. Subtract the shift offset from
the font width will prevent this.
Signed-off-by: Stefani Seibold <stefani@seibold.net> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
xfs: fix freeing of inodes not yet added to the inode cache
When freeing an inode that lost race getting added to the inode cache we
must not call into ->destroy_inode, because that would delete the inode
that won the race from the inode cache radix tree.
This patch uses splits a new xfs_inode_free helper out of xfs_ireclaim
and uses that plus __destroy_inode to make sure we really only free
the memory allocted for the inode that lost the race, and not mess with
the inode cache state.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Sandeen <sandeen@sandeen.net> Reported-by: Alex Samad <alex@samad.com.au> Reported-by: Andrew Randrianasulu <randrik@mail.ru> Reported-by: Stephane <sharnois@max-t.com> Reported-by: Tommy <tommy@news-service.com> Reported-by: Miah Gregory <mace@darksilence.net> Reported-by: Gabriel Barazer <gabriel@oxeva.fr> Reported-by: Leandro Lucarella <llucax@gmail.com> Reported-by: Daniel Burr <dburr@fami.com.au> Reported-by: Nickolay <newmail@spaces.ru> Reported-by: Michael Guntsche <mike@it-loops.com> Reported-by: Dan Carley <dan.carley+linuxkern-bugs@gmail.com> Reported-by: Michael Ole Olsen <gnu@gmx.net> Reported-by: Michael Weissenbacher <mw@dermichi.com> Reported-by: Martin Spott <Martin.Spott@mgras.net> Reported-by: Christian Kujau <lists@nerdbynature.de> Tested-by: Michael Guntsche <mike@it-loops.com> Tested-by: Dan Carley <dan.carley+linuxkern-bugs@gmail.com> Tested-by: Christian Kujau <lists@nerdbynature.de>
When we want to tear down an inode that lost the add to the cache race
in XFS we must not call into ->destroy_inode because that would delete
the inode that won the race from the inode cache radix tree.
This patch provides the __destroy_inode helper needed to fix this,
the actual fix will be in th next patch. As XFS was the only reason
destroy_inode was exported we shift the export to the new __destroy_inode.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Currently inode_init_always calls into ->destroy_inode if the additional
initialization fails. That's not only counter-intuitive because
inode_init_always did not allocate the inode structure, but in case of
XFS it's actively harmful as ->destroy_inode might delete the inode from
a radix-tree that has never been added. This in turn might end up
deleting the inode for the same inum that has been instanciated by
another process and cause lots of cause subtile problems.
Also in the case of re-initializing a reclaimable inode in XFS it would
free an inode we still want to keep alive.
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
[S390] kernel: Storing machine flags early in lowcore
Currently, the machine_flags are stored late in the startup
initialization which results in failing machine type checks
(e.g. for MACHINE_IS_VM).
To allow these checks, store the machine flags in the lowcore
when the machine type has been detected.
Peter Zijlstra [Thu, 6 Aug 2009 16:06:26 +0000 (18:06 +0200)]
perf_counter: Fix double list iteration in per task precise stats
Brice Goglin reported this crash with per task precise stats:
> I finally managed to test the threaded perfcounter statistics (thanks a
> lot for implementing it). I am running 2.6.31-rc5 (with the AMD
> magny-cours patches but I don't think they matter here). I am trying to
> measure local/remote memory accesses per thread during the well-known
> stream benchmark. It's compiled with OpenMP using 16 threads on a
> quad-socket quad-core barcelona machine.
>
> Command line is:
> /mnt/scratch/bgoglin/cpunode/linux-2.6.31/tools/perf/perf record -f -s
> -e r1000001e0 -e r1000002e0 -e r1000004e0 -e r1000008e0 ./stream
>
> It seems to work fine with a single -e <counter> on the command line
> while it crashes when there are at least 2 of them.
> It seems to work fine without -s as well.
A silly copy-paste resulted in a messed up iteration which would
cause the OOPS.
Peter Zijlstra [Wed, 5 Aug 2009 12:05:16 +0000 (14:05 +0200)]
perf: Auto-detect libelf
Adds autodetection for libelf as well, and simplifies the
libbfd code. Furthermore, fail make with an error when libelf
is not found and warn about the lack of libbfd.
Also provide an option to build a 32bit version even though you
might be running a 64bit kernel.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Seemingly we don't have a .symtab when we actually can find it
if we use the .note.gnu.build-id ELF section put in place by
some distros. Use it and find the symbols we need.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
perf_counter/powerpc: Check oprofile_cpu_type for NULL before using it
If the current CPU doesn't support performance counters,
cur_cpu_spec->oprofile_cpu_type can be NULL. The current
perf_counter modules don't test for that case and would thus
crash at boot time.
Bug reported by David Woodhouse.
Reported-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Paul Mackerras <paulus@samba.org>
LKML-Reference: <19066.48028.446975.501454@cargo.ozlabs.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Sheng Yang [Thu, 6 Aug 2009 05:31:56 +0000 (13:31 +0800)]
intel-iommu: Fix enabling snooping feature by mistake
Two defects work together result in KVM device passthrough randomly can't
work:
1. iommu_snooping is not initialized to zero when vm_iommu_init() called.
So it is possible to get a random value.
2. One line added by commit 2c2e2c38("IOMMU Identity Mapping Support")
change the code path, let it bypass domain_update_iommu_cap(), as well as
missing the increment of domain iommu reference count.
The latter is also likely to cause a leak of domains on repeated VMM
assignment and deassignment.
Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Input: wistron_btns - support Prestigio Wifi RF kill button
The Prestigio 157, an old no-name clone laptop uses input keys very
similar to the Wistron 1557/MS2141 with the addition of BIOS-controlled
wireless radio frequency kill switch.
This patch adds support for the RF kill switch control and adds manual
identification of the model.
The Prestigio does not expose any recognisable identity via dmidecode
and so requires manual selection at module init using
drm/radeon/kms: Fix caching mode selection for GTT object
GTT object can either be cached,uncached or wc just let core ttm
pick the best mode according to how the bo driver and GTT memory
type was initialized.
Signed-off-by: Jerome Glisse <jglisse@redhat.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
Peter Zijlstra [Wed, 5 Aug 2009 18:41:04 +0000 (20:41 +0200)]
ftrace: Fix perf-tracepoint OOPS
Not all tracepoints are created equal, in specific the ftrace
tracepoints are created with TRACE_EVENT_FORMAT() which does
not generate the needed bits to tie them into perf counters.
For those events, don't create the 'id' file and fail
->profile_enable when their ID is specified through other
means.
Reported-by: Chris Mason <chris.mason@oracle.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1249497664.5890.4.camel@laptop>
[ v2: fix build error in the !CONFIG_EVENT_PROFILE case ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
Hartley Sweeten [Tue, 4 Aug 2009 22:20:45 +0000 (23:20 +0100)]
ARM: 5638/1: arch/arm/kernel/signal.c: use correct address space for CRUNCH
preserve_crunch_context() calls __copy_to_user() which expects the
destination address to be in __user space. setup_sigframe() properly
passes the destination address.
restore_crunch_context() calls __copy_from_user() which expects the
source address to be in __user space. restore_sigframe() properly
passes the source address.
This fixes {preserve/restore}_crunch_context() to accept the
address as __user space and resolves the following sparse warnings:
arch/arm/kernel/signal.c:146:31:
warning: incorrect type in argument 1 (different address spaces)
expected void [noderef] <asn:1>*to
got struct crunch_sigframe *frame
arch/arm/kernel/signal.c:156:38:
warning: incorrect type in argument 2 (different address spaces)
expected void const [noderef] <asn:1>*from
got struct crunch_sigframe *frame
arch/arm/kernel/signal.c:250:48:
warning: incorrect type in argument 1 (different address spaces)
expected struct crunch_sigframe *frame
got struct crunch_sigframe [noderef] <asn:1>*<noident>
arch/arm/kernel/signal.c:365:49:
warning: incorrect type in argument 1 (different address spaces)
expected struct crunch_sigframe *frame
got struct crunch_sigframe [noderef] <asn:1>*<noident>
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Andrew Victor [Tue, 4 Aug 2009 18:55:56 +0000 (19:55 +0100)]
ARM: 5637/1: [KS8695] Don't reference CLOCK_TICK_RATE in drivers
Stop referencing CLOCK_TICK_RATE in the KS8695 drivers, rather refer
to a KS8695_CLOCK_RATE.
Issue pointed out by Russell King on arm-linux-kernel mailing list.
Signed-off-by: Andrew Victor <linux@maxim.org.za> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
it's using an zero-initialized spinlock. This is a side-effect of:
dev_unicast_init(dev);
in alloc_netdev_mq() making use of dev->addr_list_lock.
The device has just been allocated freshly, it's not accessible
anywhere yet so no locking is needed at all - in fact it's wrong
to lock it here (the lock isnt initialized yet).
Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jiri Pirko <jpirko@redhat.com> Tested-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Peter Zijlstra [Wed, 5 Aug 2009 12:05:16 +0000 (14:05 +0200)]
perf: Auto-detect libbfd
Since the C++ demangling isn't needed for everybody and
bfd/iberty aren't widely/easily available on all machines, make
it optional.
It also allows you to forcefully disable demangling by using
NO_DEMANGLE=1 and otherwise tries to detect libbfd/libiberty
combinations that result in a compiling demangler.
Fenghua Yu [Tue, 4 Aug 2009 22:09:37 +0000 (15:09 -0700)]
intel-iommu: Correct sglist size calculation.
In domain_sg_mapping(), use aligned_nrpages() instead of hand-coded
rounding code for calculating the size of each sg elem. This means that
on IA64 we correctly round up to the MM page size, not just to the VT-d
page size.
Also remove the incorrect mm_to_dma_pfn() when intel_map_sg() calls
domain_sg_mapping() -- the 'size' variable is in VT-d pages already.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Jory A. Pratt [Mon, 3 Aug 2009 16:32:34 +0000 (09:32 -0700)]
Input: i8042 - add Asus G1S to noloop exception list
The synaptic touchpad on the Asus G1S is not properly detected when
rebooting machine or on cold boot from time to time. Adding the Asus
G1S to the noloop exception table resolves the issue.
# dmidecode 2.10
SMBIOS 2.4 present.
Handle 0x0001, DMI type 1, 27 bytes
System Information
Manufacturer: ASUSTeK Computer Inc.
Product Name: G1S
Version: 1.0
Wake-up Type: Power Switch
SKU Number:
Family:
Signed-off-by: Jory A. Pratt <geekypenguin@gmail.com> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Linus Torvalds [Tue, 4 Aug 2009 22:39:55 +0000 (15:39 -0700)]
Merge branch 'fix/hda' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6
* 'fix/hda' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
ALSA: hda - Read buffer overflow
ALSA: hda: Correct EAPD for Dell Inspiron 1525
ALSA: hda: warn on spurious response
ALSA: hda: remember last command for each codec
ALSA: hda: read CORBWP inside reg_lock
ALSA: hda: take reg_lock in azx_init_cmd_io/azx_free_cmd_io
ALSA: hda: take cmd_mutex in probe_codec()
ALSA: hda: track CIRB/CORB command/response states for each codec
ALSA: hda - Fix quirk for Toshiba Satellite A135-S4527
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6:
tty-ldisc: be more careful in 'put_ldisc' locking
tty-ldisc: turn ldisc user count into a proper refcount
tty-ldisc: make refcount be atomic_t 'users' count
Linus Torvalds [Tue, 4 Aug 2009 22:39:16 +0000 (15:39 -0700)]
Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
Make SCSI SG v4 driver enabled by default and remove EXPERIMENTAL dependency, since udev depends on BSG
block: Update topology documentation
block: Stack optimal I/O size
block: Add a wrapper for setting minimum request size without a queue
block: Make blk_queue_stack_limits use the new stacking interface
* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6: (23 commits)
[SCSI] sd: Avoid sending extended inquiry to legacy devices
[SCSI] libsas: fix wide port hotplug issues
[SCSI] libfc: fix a circular locking warning during sending RRQ
[SCSI] qla4xxx: Remove hiwat code so scsi eh does not get escalated when we can make progress
[SCSI] qla4xxx: Fix srb lookup in qla4xxx_eh_device_reset
[SCSI] qla4xxx: Fix Driver Fault Recovery Completion
[SCSI] qla4xxx: add timeout handler
[SCSI] qla4xxx: Correct Extended Sense Data Errors
[SCSI] libiscsi: disable bh in and abort handler.
[SCSI] zfcp: Fix tracing of request id for abort requests
[SCSI] zfcp: Fix wka port processing
[SCSI] zfcp: avoid double notify in lowmem scenario
[SCSI] zfcp: Add port only once to FC transport class
[SCSI] zfcp: Recover from stalled outbound queue
[SCSI] zfcp: Fix erp escalation procedure
[SCSI] zfcp: Fix logic for physical port close
[SCSI] zfcp: Use -EIO for SBAL allocation failures
[SCSI] zfcp: Use unchained mode for small ct and els requests
[SCSI] zfcp: Use correct flags for zfcp_erp_notify
[SCSI] zfcp: Return -ENOMEM for allocation failures in zfcp_fsf
...
Linus Torvalds [Tue, 4 Aug 2009 22:32:40 +0000 (15:32 -0700)]
Merge branch 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf_counter: Set the CONFIG_PERF_COUNTERS default to y if CONFIG_PROFILING=y
perf: Fix read buffer overflow
perf top: Add mwait_idle_with_hints to skip_symbols[]
perf tools: Fix faulty check
perf report: Update for the new FORK/EXIT events
perf_counter: Full task tracing
perf_counter: Collapse inherit on read()
tracing, perf_counter: Add help text to CONFIG_EVENT_PROFILE
perf_counter tools: Fix link errors with older toolchains
Linus Torvalds [Tue, 4 Aug 2009 22:32:22 +0000 (15:32 -0700)]
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: Fix race in cpupri introduced by cpumask_var changes
sched: Fix latencytop and sleep profiling vs group scheduling
Linus Torvalds [Tue, 4 Aug 2009 22:32:08 +0000 (15:32 -0700)]
Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
posix-timers: Fix oops in clock_nanosleep() with CLOCK_MONOTONIC_RAW
Linus Torvalds [Tue, 4 Aug 2009 22:31:51 +0000 (15:31 -0700)]
Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Fix missing function_graph events when we splice_read from trace_pipe
tracing: Fix invalid function_graph entry
trace: stop tracer in oops_enter()
ftrace: Only update $offset when we update $ref_func
ftrace: Fix the conditional that updates $ref_func
tracing: only truncate ftrace files when O_TRUNC is set
tracing: show proper address for trace-printk format
Linus Torvalds [Tue, 4 Aug 2009 22:28:59 +0000 (15:28 -0700)]
Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Work around compilation warning in arch/x86/kernel/apm_32.c
x86, UV: Complete IRQ interrupt migration in arch_enable_uv_irq()
x86, 32-bit: Fix double accounting in reserve_top_address()
x86: Don't use current_cpu_data in x2apic phys_pkg_id
x86, UV: Fix UV apic mode
x86, UV: Fix macros for accessing large node numbers
x86, UV: Delete mapping of MMR rangs mapped by BIOS
x86, UV: Handle missing blade-local memory correctly
x86: fix assembly constraints in native_save_fl()
x86, msr: execute on the correct CPU subset
x86: Fix assert syntax in vmlinux.lds.S
x86: Make 64-bit efi_ioremap use ioremap on MMIO regions
x86: Add quirk to make Apple MacBook5,2 use reboot=pci
x86: Fix CPA memtype reserving in the set_pages_array*() cases
x86, pat: Fix set_memory_wc related corruption
x86: fix section mismatch for i386 init code
Linus Torvalds [Tue, 4 Aug 2009 22:28:46 +0000 (15:28 -0700)]
Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq:
[CPUFREQ] Make cpufreq suspend code conditional on powerpc.
[CPUFREQ] Fix a kobject reference bug related to managed CPUs
[CPUFREQ] Do not set policy for offline cpus
[CPUFREQ] Fix NULL pointer dereference regression in conservative governor
Linus Torvalds [Tue, 4 Aug 2009 22:28:23 +0000 (15:28 -0700)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2:
nilfs2: fix missing unlock in error path of nilfs_mdt_write_page
nilfs2: fix oops due to inconsistent state in page with discrete b-tree nodes
Linus Torvalds [Mon, 3 Aug 2009 21:54:56 +0000 (14:54 -0700)]
tty-ldisc: be more careful in 'put_ldisc' locking
Use 'atomic_dec_and_lock()' to make sure that we always hold the
tty_ldisc_lock when the ldisc count goes to zero. That way we can never
race against 'tty_ldisc_try()' increasing the count again.
Linus Torvalds [Mon, 3 Aug 2009 18:11:19 +0000 (11:11 -0700)]
tty-ldisc: turn ldisc user count into a proper refcount
By using the user count for the actual lifetime rules, we can get rid of
the silly "wait_for_idle" logic, because any busy ldisc will
automatically stay around until the last user releases it. This avoids
a host of odd issues, and simplifies the code.
So now, when the last ldisc reference is dropped, we just release the
ldisc operations struct reference, and free the ldisc.
It looks obvious enough, and it does work for me, but the counting
_could_ be off. It probably isn't (bad counting in the new version would
generally imply that the old code did something really bad, like free an
ldisc with a non-zero count), but it does need some testing, and
preferably somebody looking at it.
With this change, both 'tty_ldisc_put()' and 'tty_ldisc_deref()' are
just aliases for the new ref-counting 'put_ldisc()'. Both of them
decrement the ldisc user count and free it if it goes down to zero.
They're identical functions, in other words.
But the reason they still exist as sepate functions is that one of them
was exported (tty_ldisc_deref) and had a stupid name (so I don't want to
use it as the main name), and the other one was used in multiple places
(and I didn't want to make the patch larger just to rename the users).
In addition to the refcounting, I did do some minimal cleanup. For
example, now "tty_ldisc_try()" actually returns the ldisc it got under
the lock, rather than returning true/false and then the caller would
look up the ldisc again (now without the protection of the lock).
That said, there's tons of dubious use of 'tty->ldisc' without obviously
proper locking or refcounting left. I expressly did _not_ want to try to
fix it all, keeping the patch minimal. There may or may not be bugs in
that kind of code, but they wouldn't be _new_ bugs.
That said, even if the bugs aren't new, the timing and lifetime will
change. For example, some silly code may depend on the 'tty->ldisc'
pointer not changing because they hold a refcount on the 'ldisc'. And
that's no longer true - if you hold a ref on the ldisc, the 'ldisc'
itself is safe, but tty->ldisc may change.
So the proper locking (remains) to hold tty->ldisc_mutex if you expect
tty->ldisc to be stable. That's not really a _new_ rule, but it's an
example of something that the old code might have unintentionally
depended on and hidden bugs.
Whatever. The patch _looks_ sensible to me. The only users of
ldisc->users are:
- get_ldisc() - atomically increment the count
- put_ldisc() - atomically decrements the count and releases if zero
- tty_ldisc_try_get() - creates the ldisc, and sets the count to 1.
The ldisc should then either be released, or be attached to a tty.
Linus Torvalds [Mon, 3 Aug 2009 17:58:29 +0000 (10:58 -0700)]
tty-ldisc: make refcount be atomic_t 'users' count
This is pure preparation of changing the ldisc reference counting to be
a true refcount that defines the lifetime of the ldisc. But this is a
purely syntactic change for now to make the next steps easier.
This patch should make no semantic changes at all. But I wanted to make
the ldisc refcount be an atomic (I will be touching it without locks
soon enough), and I wanted to rename it so that there isn't quite as
much confusion between 'ldo->refcount' (ldisk operations refcount) and
'ld->refcount' (ldisc refcount itself) in the same file.
So it's now an atomic 'ld->users' count. It still starts at zero,
despite having a reference from 'tty->ldisc', but that will change once
we turn it into a _real_ refcount.