- fix UP lockup
- another set of UP/SMP cleanups and simplifications
Signed-off-by: NFrank Mayhar <fmayhar@google.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Cleanup.  Imho makes the code much more understandable.  At least this
patch lessens both the source and compiled code.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

lock_timer() checks that the timer found by idr_find(timer_id) has ->it_id
== timer_id.  This buys nothing.  This check can fail only if
sys_timer_create() unlocked idr_lock after idr_get_new(), but didn't set
->it_id = new_timer_id yet.  But in that case ->it_process == NULL so
lock_timer() can't succeed anyway.

Also remove a couple of unneeded typecasts.

Note that with or without this patch we have a small problem. 
sys_timer_create() doesn't ensure that the result of setting (say)
->it_sigev_notify must be visible if lock_timer() succeeds.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

With the recent changes ->it_sigev_signo and ->it_sigev_value are only
used in sys_timer_create(), kill them.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Cleanup.

- sys_timer_create() is big and complicated. The code above the "out:"
  label relies on the fact that "error" must be == 0. This is not very
  robust, make the code more explicit. Remove the unneeded initialization
  of error.

- If idr_get_new() succeeds (as it normally should), we check the returned
  value twice. Move the "-EAGAIN" check under "if (error)".
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

posix_timer_event() always populates timer->sigq with the same numbers,
move this code into sys_timer_create().

Note that with this patch we can kill it_sigev_signo and it_sigev_value.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

- Change the code to do rcu_read_lock() instead of taking tasklist_lock,
  it is safe to get_task_struct(p) if p was found under RCU.

  However, now we must not use process's sighand/signal, they may be NULL.
  We can use current->sighand/signal instead, this "process" must belong
  to the current's thread-group.

- Factor out the common code for 2 "if (timer_event_spec)" branches, the
  !timer_event_spec case can use current too.

- use spin_lock_irq() instead of _irqsave(), kill "flags".
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

sys_timer_create() return -EINVAL if the target thread has PF_EXITING.

This doesn't really make sense, the sub-thread can die right after unlock.
And in fact, this is just wrong.  Without SIGEV_THREAD_ID good_sigevent()
returns ->group_leader, and it is very possible that the leader is already
dead.  This is OK, we shouldn't return the error in this case.

Remove this check and the comment.  Note that the "process" was found
under tasklist_lock, it must have ->sighand != NULL.

Also, remove a couple of unneeded initializations.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Change the code to get/put timer->it_process regardless of
SIGEV_THREAD_ID.  This streamlines the create/destroy paths and allows us
to simplify the usage of exit_itimers() in de_thread().
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

posix_timer_event() drops SIGEV_THREAD_ID and switches to ->group_leader
if send_sigqueue() fails.

This is not very useful and doesn't work reliably.  send_sigqueue() can
only fail if ->it_process is dead.  But it can die before it dequeues the
SI_TIMER signal, in that case the timer stops anyway.

Remove this code.  I guess it was needed a long ago to ensure that the
timer is not destroyed when when its creator thread dies.

Q: perhaps it makes sense to change sys_timer_settime() to return an error
if ->it_process is dead?
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: mingo@elte.hu
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This is the second resubmission of the posix timer rework patch, posted
a few days ago.

This includes the changes from the previous resubmittion, which addressed
Oleg Nesterov's comments, removing the RCU stuff from the patch and
un-inlining the thread_group_cputime() function for SMP.

In addition, per Ingo Molnar it simplifies the UP code, consolidating much
of it with the SMP version and depending on lower-level SMP/UP handling to
take care of the differences.

It also cleans up some UP compile errors, moves the scheduler stats-related
macros into kernel/sched_stats.h, cleans up a merge error in
kernel/fork.c and has a few other minor fixes and cleanups as suggested
by Oleg and Ingo. Thanks for the review, guys.
Signed-off-by: NFrank Mayhar <fmayhar@google.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix the UP build:

In file included from arch/x86/kernel/asm-offsets_32.c:9,
                 from arch/x86/kernel/asm-offsets.c:3:
include/linux/sched.h: In function ‘thread_group_cputime_clone_thread’:
include/linux/sched.h:2272: warning: no return statement in function returning non-void
include/linux/sched.h: In function ‘thread_group_cputime_account_user’:
include/linux/sched.h:2284: error: invalid type argument of ‘->’ (have ‘struct task_cputime’)
include/linux/sched.h:2284: error: invalid type argument of ‘->’ (have ‘struct task_cputime’)
include/linux/sched.h: In function ‘thread_group_cputime_account_system’:
include/linux/sched.h:2291: error: invalid type argument of ‘->’ (have ‘struct task_cputime’)
include/linux/sched.h:2291: error: invalid type argument of ‘->’ (have ‘struct task_cputime’)
include/linux/sched.h: In function ‘thread_group_cputime_account_exec_runtime’:
include/linux/sched.h:2298: error: invalid type argument of ‘->’ (have ‘struct task_cputime’)
distcc[14501] ERROR: compile arch/x86/kernel/asm-offsets.c on a/30 failed
make[1]: *** [arch/x86/kernel/asm-offsets.s] Error 1
Signed-off-by: NIngo Molnar <mingo@elte.hu>

fix:

 kernel/fork.c:843: error: ‘struct signal_struct’ has no member named ‘sum_sched_runtime’
 kernel/irq/handle.c:117: warning: ‘sparse_irq_lock’ defined but not used
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Overview

This patch reworks the handling of POSIX CPU timers, including the
ITIMER_PROF, ITIMER_VIRT timers and rlimit handling.  It was put together
with the help of Roland McGrath, the owner and original writer of this code.

The problem we ran into, and the reason for this rework, has to do with using
a profiling timer in a process with a large number of threads.  It appears
that the performance of the old implementation of run_posix_cpu_timers() was
at least O(n*3) (where "n" is the number of threads in a process) or worse.
Everything is fine with an increasing number of threads until the time taken
for that routine to run becomes the same as or greater than the tick time, at
which point things degrade rather quickly.

This patch fixes bug 9906, "Weird hang with NPTL and SIGPROF."

Code Changes

This rework corrects the implementation of run_posix_cpu_timers() to make it
run in constant time for a particular machine.  (Performance may vary between
one machine and another depending upon whether the kernel is built as single-
or multiprocessor and, in the latter case, depending upon the number of
running processors.)  To do this, at each tick we now update fields in
signal_struct as well as task_struct.  The run_posix_cpu_timers() function
uses those fields to make its decisions.

We define a new structure, "task_cputime," to contain user, system and
scheduler times and use these in appropriate places:

struct task_cputime {
	cputime_t utime;
	cputime_t stime;
	unsigned long long sum_exec_runtime;
};

This is included in the structure "thread_group_cputime," which is a new
substructure of signal_struct and which varies for uniprocessor versus
multiprocessor kernels.  For uniprocessor kernels, it uses "task_cputime" as
a simple substructure, while for multiprocessor kernels it is a pointer:

struct thread_group_cputime {
	struct task_cputime totals;
};

struct thread_group_cputime {
	struct task_cputime *totals;
};

We also add a new task_cputime substructure directly to signal_struct, to
cache the earliest expiration of process-wide timers, and task_cputime also
replaces the it_*_expires fields of task_struct (used for earliest expiration
of thread timers).  The "thread_group_cputime" structure contains process-wide
timers that are updated via account_user_time() and friends.  In the non-SMP
case the structure is a simple aggregator; unfortunately in the SMP case that
simplicity was not achievable due to cache-line contention between CPUs (in
one measured case performance was actually _worse_ on a 16-cpu system than
the same test on a 4-cpu system, due to this contention).  For SMP, the
thread_group_cputime counters are maintained as a per-cpu structure allocated
using alloc_percpu().  The timer functions update only the timer field in
the structure corresponding to the running CPU, obtained using per_cpu_ptr().

We define a set of inline functions in sched.h that we use to maintain the
thread_group_cputime structure and hide the differences between UP and SMP
implementations from the rest of the kernel.  The thread_group_cputime_init()
function initializes the thread_group_cputime structure for the given task.
The thread_group_cputime_alloc() is a no-op for UP; for SMP it calls the
out-of-line function thread_group_cputime_alloc_smp() to allocate and fill
in the per-cpu structures and fields.  The thread_group_cputime_free()
function, also a no-op for UP, in SMP frees the per-cpu structures.  The
thread_group_cputime_clone_thread() function (also a UP no-op) for SMP calls
thread_group_cputime_alloc() if the per-cpu structures haven't yet been
allocated.  The thread_group_cputime() function fills the task_cputime
structure it is passed with the contents of the thread_group_cputime fields;
in UP it's that simple but in SMP it must also safely check that tsk->signal
is non-NULL (if it is it just uses the appropriate fields of task_struct) and,
if so, sums the per-cpu values for each online CPU.  Finally, the three
functions account_group_user_time(), account_group_system_time() and
account_group_exec_runtime() are used by timer functions to update the
respective fields of the thread_group_cputime structure.

Non-SMP operation is trivial and will not be mentioned further.

The per-cpu structure is always allocated when a task creates its first new
thread, via a call to thread_group_cputime_clone_thread() from copy_signal().
It is freed at process exit via a call to thread_group_cputime_free() from
cleanup_signal().

All functions that formerly summed utime/stime/sum_sched_runtime values from
from all threads in the thread group now use thread_group_cputime() to
snapshot the values in the thread_group_cputime structure or the values in
the task structure itself if the per-cpu structure hasn't been allocated.

Finally, the code in kernel/posix-cpu-timers.c has changed quite a bit.
The run_posix_cpu_timers() function has been split into a fast path and a
slow path; the former safely checks whether there are any expired thread
timers and, if not, just returns, while the slow path does the heavy lifting.
With the dedicated thread group fields, timers are no longer "rebalanced" and
the process_timer_rebalance() function and related code has gone away.  All
summing loops are gone and all code that used them now uses the
thread_group_cputime() inline.  When process-wide timers are set, the new
task_cputime structure in signal_struct is used to cache the earliest
expiration; this is checked in the fast path.

Performance

The fix appears not to add significant overhead to existing operations.  It
generally performs the same as the current code except in two cases, one in
which it performs slightly worse (Case 5 below) and one in which it performs
very significantly better (Case 2 below).  Overall it's a wash except in those
two cases.

I've since done somewhat more involved testing on a dual-core Opteron system.

Case 1: With no itimer running, for a test with 100,000 threads, the fixed
	kernel took 1428.5 seconds, 513 seconds more than the unfixed system,
	all of which was spent in the system.  There were twice as many
	voluntary context switches with the fix as without it.

Case 2: With an itimer running at .01 second ticks and 4000 threads (the most
	an unmodified kernel can handle), the fixed kernel ran the test in
	eight percent of the time (5.8 seconds as opposed to 70 seconds) and
	had better tick accuracy (.012 seconds per tick as opposed to .023
	seconds per tick).

Case 3: A 4000-thread test with an initial timer tick of .01 second and an
	interval of 10,000 seconds (i.e. a timer that ticks only once) had
	very nearly the same performance in both cases:  6.3 seconds elapsed
	for the fixed kernel versus 5.5 seconds for the unfixed kernel.

With fewer threads (eight in these tests), the Case 1 test ran in essentially
the same time on both the modified and unmodified kernels (5.2 seconds versus
5.8 seconds).  The Case 2 test ran in about the same time as well, 5.9 seconds
versus 5.4 seconds but again with much better tick accuracy, .013 seconds per
tick versus .025 seconds per tick for the unmodified kernel.

Since the fix affected the rlimit code, I also tested soft and hard CPU limits.

Case 4: With a hard CPU limit of 20 seconds and eight threads (and an itimer
	running), the modified kernel was very slightly favored in that while
	it killed the process in 19.997 seconds of CPU time (5.002 seconds of
	wall time), only .003 seconds of that was system time, the rest was
	user time.  The unmodified kernel killed the process in 20.001 seconds
	of CPU (5.014 seconds of wall time) of which .016 seconds was system
	time.  Really, though, the results were too close to call.  The results
	were essentially the same with no itimer running.

Case 5: With a soft limit of 20 seconds and a hard limit of 2000 seconds
	(where the hard limit would never be reached) and an itimer running,
	the modified kernel exhibited worse tick accuracy than the unmodified
	kernel: .050 seconds/tick versus .028 seconds/tick.  Otherwise,
	performance was almost indistinguishable.  With no itimer running this
	test exhibited virtually identical behavior and times in both cases.

In times past I did some limited performance testing.  those results are below.

On a four-cpu Opteron system without this fix, a sixteen-thread test executed
in 3569.991 seconds, of which user was 3568.435s and system was 1.556s.  On
the same system with the fix, user and elapsed time were about the same, but
system time dropped to 0.007 seconds.  Performance with eight, four and one
thread were comparable.  Interestingly, the timer ticks with the fix seemed
more accurate:  The sixteen-thread test with the fix received 149543 ticks
for 0.024 seconds per tick, while the same test without the fix received 58720
for 0.061 seconds per tick.  Both cases were configured for an interval of
0.01 seconds.  Again, the other tests were comparable.  Each thread in this
test computed the primes up to 25,000,000.

I also did a test with a large number of threads, 100,000 threads, which is
impossible without the fix.  In this case each thread computed the primes only
up to 10,000 (to make the runtime manageable).  System time dominated, at
1546.968 seconds out of a total 2176.906 seconds (giving a user time of
629.938s).  It received 147651 ticks for 0.015 seconds per tick, still quite
accurate.  There is obviously no comparable test without the fix.
Signed-off-by: NFrank Mayhar <fmayhar@google.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] Fix PCI_DMA_BUS_IS_PHYS for ARM
  [ARM] 5247/1: tosa: SW_EAR_IN support
  [ARM] 5246/1: tosa: add proper clock alias for tc6393xb clock
  [ARM] 5245/1: Fix warning about unused return value in drivers/pcmcia
  [ARM] OMAP: Fix MMC device data
  imx serial: fix rts handling for non imx1 based hardware
  imx serial: set RXD mux bit on i.MX27 and i.MX31
  i.MX serial: fix init failure
  pcm037: add rts/cts support for serial port

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
  [libata] LBA28/LBA48 off-by-one bug in ata.h
  sata_inic162x: enable LED blinking
  ata: duplicate variable sparse warning

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
  PCI: re-add debug prints for unmodified BARs
  PCI: fix pciehp_free_irq()
  PCI Hotplug: fakephp: fix deadlock... again
  PCI: Fix printk warnings in setup-bus.c
  PCI: Fix printk warnings in probe.c
  PCI/iommu: blacklist DMAR on Intel G31/G33 chipsets

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  niu: panic on reset
  netlink: fix overrun in attribute iteration
  [Bluetooth] Fix regression from using default link policy
  ath9k: Assign seq# when mac80211 requests this

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc: Fix user_regset 'n' field values.
  sparc64: Fix PCI error interrupt registry on PSYCHO.
  sparc32: Fix function signature of of_bus_sbus_get_flags().
  sparc64: Fix interrupt register calculations on Psycho and Sabre.

- 8-bit interface mode never worked properly.  The only adapter I have
  which supports the 8b mode (the Jmicron) had some problems with its
  clock wiring and they discovered it only now.  We also discovered that
  ProHG media is more sensitive to the ordering of initialization
  commands.

- Make the driver fall back to highest supported mode instead of always
  falling back to serial.  The driver will attempt the switch to 8b mode
  for any new MSPro card, but not all of them support it.  Previously,
  these new cards ended up in serial mode, which is not the best idea
  (they work fine with 4b, after all).

- Edit some macros for better conformance to Sony documentation
Signed-off-by: NAlex Dubov <oakad@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Herton Krzesinski reports that the error-checking changes in
04ebd4ae ("block/ioctl.c and
fs/partition/check.c: check value returned by add_partition") cause his
buggy USB camera to no longer mount.  "The camera is an Olympus X-840.
The original issue comes from the camera itself: its format program
creates a partition with an off by one error".

Buggy devices happen.  It is better for the kernel to warn and to proceed
with the mount.
Reported-by: NHerton Ronaldo Krzesinski <herton@mandriva.com.br>
Cc: Abdel Benamrouche <draconux@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the section mismatch warning generated by the incorrect naming of
s3c24xx_spidrv which should be s3c24xx_spi_driver:

WARNING: drivers/spi/spi_s3c24xx.o(.data+0x4):
  Section mismatch in reference from the variable s3c24xx_spidrv
  to the (unknown reference) .exit.text:(unknown)
Signed-off-by: NBen Dooks <ben-linux@fluff.org>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When suspending the system with atmel_lcdfb enabled, I sometimes see
this:

	atmel_lcdfb atmel_lcdfb.0: FIFO underflow 0x10

Which can be explained by the fact that we're not stopping the LCD
controller and its DMA engine when suspending, we're just gating the
clocks to them.

There's another potential issue which may be harder to trigger but
much more nasty: If we gate the clocks at _just_ the right moment,
e.g. when the DMA engine is doing a bus transaction, we may cause the
DMA engine to violate the system bus protocol and cause a lockup.

Avoid these issues by shutting down the LCD controller before entering
suspend (and restarting it when resuming). This prevents the underrun
from happening in the first place, and prevents whatever nastiness is
happening when the bus clock stops in the middle of a DMA transfer.
Signed-off-by: NHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If you are on ia64 and you modprobe xpc then modprobe -r xpc, you
immediately get a panic.  xpc depends on xp which depends on gru for a
symbol.  That symbol is only used when we are running on UV hardware.

Currently, the GRU driver detects we are not on UV hardware and does no
initializing.  It does not do the same check when unloading.  As a result,
the gru driver attempts to tear down stuff that was not setup.

This is a simple two-line workaround to get us through this release.  Once
2.6.28 is opened, we need to rework the symbols that xp is depending on
from gru so the gru driver can properly fail to load when hardware is not
available.
Signed-off-by: NRobin Holt <holt@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It should be linux-uvc-devel@lists.berlios.de.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Provide summary ABI docs about the /sys/class/gpio files.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The iterator for_each_zone_zonelist() uses a struct zoneref *z cursor when
scanning zonelists to keep track of where in the zonelist it is.  The
zoneref that is returned corresponds to the the next zone that is to be
scanned, not the current one.  It was intended to be treated as an opaque
list.

When the page allocator is scanning a zonelist, it marks elements in the
zonelist corresponding to zones that are temporarily full.  As the
zonelist is being updated, it uses the cursor here;

  if (NUMA_BUILD)
        zlc_mark_zone_full(zonelist, z);

This is intended to prevent rescanning in the near future but the zoneref
cursor does not correspond to the zone that has been found to be full.
This is an easy misunderstanding to make so this patch corrects the
problem by changing zoneref cursor to be the current zone being scanned
instead of the next one.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@kernel.org>		[2.6.26.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixes two DMA bugs in the pxa2xx_spi driver.  The first bug is in all
versions of this driver; the second was introduced in the 2.6.20 kernel,
and prevents using the driver with chips like m25p16 flash (which can
issue large DMA reads).

 1. Zero length transfers are permitted for use to insert timing,
    but pxa2xx_spi.c will fail if this is requested in DMA mode.
    Fixed by using programmed I/O (PIO) mode for such transfers.

 2. Transfers larger than 8191 are not permitted in DMA mode.  A
    test for length rejects all large transfers regardless of DMA
    or PIO mode.  Worked around by rejecting only large transfers
    with DMA mapped buffers, and forcing all other transfers
    larger than 8191 to use PIO mode.  A rate limited warning is
    issued for DMA transfers forced to PIO mode.

This patch should apply to all kernels back to and including 2.6.20;
it was test patched against 2.6.20.  An additional patch would be
required for older kernels, but those versions are very buggy anyway.
Signed-off-by: NNed Forrester <nforrester@whoi.edu>
Cc: Vernon Sauder <vernoninhand@gmail.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fixes several chipselect bugs in the pxa2xx_spi driver.  These bugs are in
all versions of this driver and prevent using it with chips like m25p16
flash.

 1. The spi_transfer.cs_change flag is handled too early:
    before spi_transfer.delay_usecs applies, thus making the
    delay ineffective at holding chip select.

 2. spi_transfer.delay_usecs is ignored on the last transfer
    of a message (likewise not holding chipselect long enough).

 3. If spi_transfer.cs_change is set on the last transfer, the
    chip select is always disabled, instead of the intended
    meaning: optionally holding chip select enabled for the
    next message.

Those first three bugs were fixed with a relocation of delays
and chip select de-assertions.

 4. If a message has the cs_change flag set on the last transfer,
    and had the chip select stayed enabled as requested (see 3,
    above), it would not have been disabled if the next message is
    for a different chip.  Fixed by dropping chip select regardless
    of cs_change at end of a message, if there is no next message
    or if the next message is for a different chip.

This patch should apply to all kernels back to and including 2.6.20;
it was test patched against 2.6.20.  An additional patch would be
required for older kernels, but those versions are very buggy anyway.
Signed-off-by: NNed Forrester <nforrester@whoi.edu>
Cc: Vernon Sauder <vernoninhand@gmail.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: <stable@kernel.org>		[2.6.25.x, 2.6.26.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Error out on transfer length != multiple of bytes per word with -EINVAL.
Fixes a buffer overrun crash if length < bytes per word.
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Acked-by: NJoakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit a61f5345 (spi_mpc83xx clockrate fixes) broke clockrate calculation
for low speeds.  SPMODE_DIV16 should be set if the divider is higher than
64, not only if the divider gets clipped to 1024.

Furthermore, the clipping check was off by a factor 16 as well.
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A "Quicklists:          0 kB" line has just started appearing in
/proc/meminfo, but most architectures (including x86) don't have
them configured, so #ifdef it, like the highmem lines.

And those architectures which do have quicklists configured are
using them for page tables: so let's place it next to PageTables.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NChristoph Lameter <cl@linux-foundation.org>
Acked-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This fixes:

  =============================================
  [ INFO: possible recursive locking detected ]
  2.6.27-rc5-00283-g70bb0896 #68
  ---------------------------------------------
  touch/6855 is trying to acquire lock:
   (&info->bfs_lock){--..}, at: [<c02262f5>] bfs_delete_inode+0x9e/0x18c

  but task is already holding lock:
   (&info->bfs_lock){--..}, at: [<c0226c00>] bfs_create+0x45/0x187

  other info that might help us debug this:
  2 locks held by touch/6855:
   #0:  (&type->i_mutex_dir_key#5){--..}, at: [<c018ad13>] do_filp_open+0x10b/0x62f
   #1:  (&info->bfs_lock){--..}, at: [<c0226c00>] bfs_create+0x45/0x187

  stack backtrace:
  Pid: 6855, comm: touch Not tainted 2.6.27-rc5-00283-g70bb0896 #68
   [<c013e769>] validate_chain+0x458/0x9f4
   [<c013bece>] ? trace_hardirqs_off+0xb/0xd
   [<c013f36b>] __lock_acquire+0x666/0x6e0
   [<c013f440>] lock_acquire+0x5b/0x77
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c06aab74>] mutex_lock_nested+0xbc/0x234
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c02262f5>] ? bfs_delete_inode+0x9e/0x18c
   [<c02262f5>] bfs_delete_inode+0x9e/0x18c
   [<c0226257>] ? bfs_delete_inode+0x0/0x18c
   [<c01925e1>] generic_delete_inode+0x94/0xfe
   [<c019265d>] generic_drop_inode+0x12/0x12f
   [<c0191b7e>] iput+0x4b/0x4e
   [<c0226d1e>] bfs_create+0x163/0x187
   [<c0188b42>] vfs_create+0xa6/0x114
   [<c018adb5>] do_filp_open+0x1ad/0x62f
   [<c0107cdc>] ? native_sched_clock+0x82/0x96
   [<c06ac309>] ? _spin_unlock+0x27/0x3c
   [<c019379e>] ? alloc_fd+0xbf/0xc9
   [<c06ae2f4>] ? sub_preempt_count+0x9d/0xab
   [<c019379e>] ? alloc_fd+0xbf/0xc9
   [<c0180391>] do_sys_open+0x42/0xb8
   [<c041d564>] ? trace_hardirqs_on_thunk+0xc/0x10
   [<c0180449>] sys_open+0x1e/0x26
   [<c01038bd>] sysenter_do_call+0x12/0x31
   =======================

The problem is that we don't unlock the bfs->lock mutex before calling
iput (we do in the other cases).
Signed-off-by: NEric Sesterhenn <snakebyte@gmx.de>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no description of bit 4 of coredump_filter in the
documentation.  This patch adds it.
Signed-off-by: NHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If all the cpus in a cpuset are offlined, the tasks in it will be moved to
the nearest ancestor with non-empty cpus.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPaul Jackson <pj@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After the patch:

commit 0b2f630a
Author: Miao Xie <miaox@cn.fujitsu.com>
Date:   Fri Jul 25 01:47:21 2008 -0700

    cpusets: restructure the function update_cpumask() and update_nodemask()

It might happen that 'echo 0 > /cpuset/sub/cpus' returned failure but 'cpus'
has been changed, because cpus was changed before calling heap_init() which
may return -ENOMEM.

This patch restores the orginal behavior.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NPaul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

akpm: these have no callers at this time, but they shall soon, so let's
get them right.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NHiroshi DOYU <Hiroshi.DOYU@nokia.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Print parent directory name as well.

The aim is to catch non-creation of parent directory when proc_mkdir will
return NULL and all subsequent registrations go directly in /proc instead
of intended directory.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ Fixed insane printk string while at it.  - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I recently bought 3 HGST P7K500-series 500GB SATA drives and
had trouble accessing the block right on the LBA28-LBA48 border.
Here's how it fails (same for all 3 drives):

  # dd if=/dev/sdc bs=512 count=1 skip=268435455 > /dev/null
  dd: reading `/dev/sdc': Input/output error
  0+0 records in
  0+0 records out
  0 bytes (0 B) copied, 0.288033 seconds, 0.0 kB/s
  # dmesg
  ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
  ata1.00: BMDMA stat 0x25
  ata1.00: cmd c8/00:08:f8:ff:ff/00:00:00:00:00/ef tag 0 dma 4096 in
  res 51/04:08:f8:ff:ff/00:00:00:00:00/ef Emask 0x1 (device error)
  ata1.00: status: { DRDY ERR }
  ata1.00: error: { ABRT }
  ata1.00: configured for UDMA/33
  ata1: EH complete
  ...

After some investigations, it turned out this seems to be caused
by misinterpretation of the ATA specification on LBA28 access.
Following part is the code in question:

  === include/linux/ata.h ===
  static inline int lba_28_ok(u64 block, u32 n_block)
  {
    /* check the ending block number */
    return ((block + n_block - 1) < ((u64)1 << 28)) && (n_block <= 256);
  }

HGST drive (sometimes) fails with LBA28 access of {block = 0xfffffff,
n_block = 1}, and this behavior seems to be comformant. Other drives,
including other HGST drives are not that strict, through.

>From the ATA specification:
(http://www.t13.org/Documents/UploadedDocuments/project/d1410r3b-ATA-ATAPI-6.pdf)

  8.15.29  Word (61:60): Total number of user addressable sectors
  This field contains a value that is one greater than the total number
  of user addressable sectors (see 6.2). The maximum value that shall
  be placed in this field is 0FFFFFFFh.

So the driver shouldn't use the value of 0xfffffff for LBA28 request
as this exceeds maximum user addressable sector. The logical maximum
value for LBA28 is 0xffffffe.

The obvious fix is to cut "- 1" part, and the patch attached just do
that. I've been using the patched kernel for about a month now, and
the same fix is also floating on the net for some time. So I believe
this fix works reliably.

Just FYI, many Windows/Intel platform users also seems to be struck
by this, and HGST has issued a note pointing to Intel ICH8/9 driver.

  "28-bit LBA command is being used to access LBAs 29-bits in length"
http://www.hitachigst.com/hddt/knowtree.nsf/cffe836ed7c12018862565b000530c74/b531b8bce8745fb78825740f00580e23

Also, *BSDs seems to have similar fix included sometime around ~2004,
through I have not checked out exact portion of the code.
Signed-off-by: NTaisuke Yamada <tai@rakugaki.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>