This patch fixes a rare deadlock that can occur when the kernel
is not able to empty out the RX ring quickly enough. Below follows
a detailed description of the bug and the fix.

As long as the OS can empty out the RX buffers at a rate faster than
the hardware can fill them, there is no problem. If, for some reason,
the OS fails to empty the RX ring fast enough, the hardware GDACTDPA
pointer will catch up to the head, notice the not-empty condition,
ad stop. However, RX packets may still continue arriving on the wire.
The spidernet chip can save some limited number of these in local RAM.
When this local ram fills up, the spider chip will issue an interrupt
indicating this (GHIINT0STS will show ERRINT, and the GRMFLLINT bit
will be set in GHIINT1STS).  When te RX ram full condition occurs,
a certain bug/feature is triggered that has to be specially handled.
This section describes the special handling for this condition.

When the OS finally has a chance to run, it will empty out the RX ring.
In particular, it will clear the descriptor on which the hardware had
stopped. However, once the hardware has decided that a certain
descriptor is invalid, it will not restart at that descriptor; instead
it will restart at the next descr. This potentially will lead to a
deadlock condition, as the tail pointer will be pointing at this descr,
which, from the OS point of view, is empty; the OS will be waiting for
this descr to be filled. However, the hardware has skipped this descr,
and is filling the next descrs. Since the OS doesn't see this, there
is a potential deadlock, with the OS waiting for one descr to fill,
while the hardware is waiting for a differen set of descrs to become
empty.

A call to show_rx_chain() at this point indicates the nature of the
problem. A typical print when the network is hung shows the following:

net eth1: Spider RX RAM full, incoming packets might be discarded!
net eth1: Total number of descrs=256
net eth1: Chain tail located at descr=255
net eth1: Chain head is at 255
net eth1: HW curr desc (GDACTDPA) is at 0
net eth1: Have 1 descrs with stat=xa0800000
net eth1: HW next desc (GDACNEXTDA) is at 1
net eth1: Have 127 descrs with stat=x40800101
net eth1: Have 1 descrs with stat=x40800001
net eth1: Have 126 descrs with stat=x40800101
net eth1: Last 1 descrs with stat=xa0800000

Both the tail and head pointers are pointing at descr 255, which is
marked xa... which is "empty". Thus, from the OS point of view, there
is nothing to be done. In particular, there is the implicit assumption
that everything in front of the "empty" descr must surely also be empty,
as explained in the last section. The OS is waiting for descr 255 to
become non-empty, which, in this case, will never happen.

The HW pointer is at descr 0. This descr is marked 0x4.. or "full".
Since its already full, the hardware can do nothing more, and thus has
halted processing. Notice that descrs 0 through 254 are all marked
"full", while descr 254 and 255 are empty. (The "Last 1 descrs" is
descr 254, since tail was at 255.) Thus, the system is deadlocked,
and there can be no forward progress; the OS thinks there's nothing
to do, and the hardware has nowhere to put incoming data.

This bug/feature is worked around with the spider_net_resync_head_ptr()
routine. When the driver receives RX interrupts, but an examination
of the RX chain seems to show it is empty, then it is probable that
the hardware has skipped a descr or two (sometimes dozens under heavy
network conditions). The spider_net_resync_head_ptr() subroutine will
search the ring for the next full descr, and the driver will resume
operations there.  Since this will leave "holes" in the ring, there
is also a spider_net_resync_tail_ptr() that will skip over such holes.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

Avoid kernel crash in mm/slab.c due to double-free of pointer.

If the ethernet interface is brought down while there is still
RX traffic in flight, the device shutdown routine can end up
trying to double-free an skb, leading to a crash in mm/slab.c
Avoid the double-free by nulling out the skb pointer.
Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
  firewire: Only set client->iso_context if allocation was successful.
  ieee1394: fix to ether1394_tx in ether1394.c
  firewire: fix hang after card ejection

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband:
  IB/mlx4: Make sure inline data segments don't cross a 64 byte boundary
  IB/mlx4: Handle FW command interface rev 3
  IB/mlx4: Handle buffer wraparound in __mlx4_ib_cq_clean()
  IB/mlx4: Get rid of max_inline_data calculation
  IB/mlx4: Handle new FW requirement for send request prefetching
  IB/mlx4: Fix warning in rounding up queue sizes
  IB/mlx4: Fix handling of wq->tail for send completions

This patch fixes an OOPS on cdev release for an fd where iso context
creation failed.
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  [MIPS] Don't drag a platform specific header into generic arch code.

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
  [POWERPC] Fix powermac late initcall to only run on powermac
  [POWERPC] PowerPC: Prevent data exception in kernel space (32-bit)

Reorder my CREDIT entry to make it in alphabetic order by last name.
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

WARNING: arch/x86_64/kernel/built-in.o(.text+0xace9): Section mismatch: reference to .init.text: (between 'get_mtrr_state' and 'mtrr_wrmsr')
WARNING: arch/x86_64/kernel/built-in.o(.text+0xad09): Section mismatch: reference to .init.text: (between 'get_mtrr_state' and 'mtrr_wrmsr')
WARNING: arch/x86_64/kernel/built-in.o(.text+0xad38): Section mismatch: reference to .init.text: (between 'get_mtrr_state' and 'mtrr_wrmsr')
WARNING: drivers/built-in.o(.text+0x3a680): Section mismatch: reference to .init.text:acpi_map_pxm_to_node (between 'acpi_get_node' and 'acpi_lock_ac_dir')

AK: also marked mtrr_bp_init __init to avoid some more warnings
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

- Disable CLFLUSH again; it is still broken. Always do WBINVD.
- Always flush in the i386 case, not only when there are deferred pages.

These are both brute-force inefficient fixes, to be improved
next release cycle.

The changes to i386 are a little more extensive than strictly
needed (some dead code added), but it is more similar to the x86-64 version
now and the dead code will be used soon.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Right now Kprobes cannot write to the write protected kernel text when
DEBUG_RODATA is enabled. Disallow this in Kconfig for now.

Temporary fix for 2.6.22. In .23 add code to temporarily
unprotect it.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

It's already annoying that they appear on x86 now -- that's for the 3button
emulation needed on x86 macs -- but at least don't make them default.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Not directly related to x86, but I got tired of seeing these warnings on every
kconfig update when building on a non m68k box:

drivers/input/keyboard/Kconfig:170:warning: 'select' used by config symbol 'KEYBOARD_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'
drivers/input/mouse/Kconfig:182:warning: 'select' used by config symbol 'MOUSE_ATARI' refers to undefined symbol 'ATARI_KBD_CORE'

I moved the definition of ATARI_KBD_CORE into drivers/input/keyboard/Kconfig
so it's always seen by Kconfig.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Several reports that VIA bridges don't support DAC and corrupt
data.  I don't know if it's fixed, but let's just blacklist
them all for now.

It can be overwritten with iommu=usedac
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

They had the same syscall number.

Pointed out by Davide Libenzi
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Correctly convert the u64 arguments from 32bit to 64bit.

Pointed out by Heiko Carstens.

I guess this proves Linus' theory that nobody uses the more exotic Linux
specific syscalls.  It wasn't discovered by a user.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

For some platforms it's definitions may conflict.  So that's the one-liner.
The rest is 10 square kilometers of collateral damage fixup this include
used to paper over.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Current ppc64_defconfig kernel fails to boot on iSeries, dying with:

Unable to handle kernel paging request for data at address 0x00000000
Faulting instruction address: 0xc00000000071b258
Oops: Kernel access of bad area, sig: 11 [#1]
SMP NR_CPUS=32 iSeries
<snip>
NIP [c00000000071b258] .iSeries_src_init+0x34/0x64
LR [c000000000701bb4] .kernel_init+0x1fc/0x3bc
Call Trace:
[c000000007d0be30] [0000000000008000] 0x8000 (unreliable)
[c000000007d0bea0] [c000000000701bb4] .kernel_init+0x1fc/0x3bc
[c000000007d0bf90] [c0000000000262d4] .kernel_thread+0x4c/0x68
Instruction dump:
e922cba8 3880ffff 78840420 f8010010 f821ff91 60000000 e8090000 78095fe3
4182002c e922cb58 e862cbb0 e9290140 <e8090000> f8410028 7c0903a6 e9690010
Kernel panic - not syncing: Attempted to kill init!

This happens because some powermac code unconditionally sets
ppc_md.progress to NULL.  This patch makes sure the powermac late
initcall is only run on powermac machines.
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

The "is_exec" branch of the protection check in do_page_fault()
didn't do anything on 32-bit PowerPC.  So if a userland program
jumps to a page with Linux protection flags "---p", all the tests
happily fall through, and handle_mm_fault() is called, which in
turn calls handle_pte_fault(), which calls update_mmu_cache(),
which goes flush the dcache to a page with no access rights.

Boom.

This fixes it.
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>

The patch adds fragments caused by rh_alloc_align() back to free list, instead
of allocating the whole chunk of memory.  This will greatly improve memory
utilization managed by rheap.

It solves MURAM not enough problem with 3 UCCs enabled on MPC8323.
Signed-off-by: Li Yang <leoli@freescale.com>
Acked-by: Joakim Tjernlund <joakim.tjernlund@transmode.se> 
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

* master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh64-2.6:
  sh64: Handle -ERESTART_RESTARTBLOCK for restartable syscalls.

* master.kernel.org:/pub/scm/linux/kernel/git/lethal/sh-2.6:
  sh: Handle -ERESTART_RESTARTBLOCK for restartable syscalls.
  sh: oops_enter()/oops_exit() in die().
  sh: Fix restartable syscall arg5 clobbering.

* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
  [S390] Move psw_set_key.
  [S390] Add oops_enter()/oops_exit() calls to die().
  [S390] Print list of modules on die().
  [S390] Fix yet another two section mismatches.
  [S390] Fix zfcpdump header
  [S390] Missing blank when appending cio_ignore kernel parameter

* 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6:
  [XFS] Update the MAINTAINERS file entry for XFS - change git repo name.
  [XFS] s/memclear_highpage_flush/zero_user_page/
  [XFS] Update the MAINTAINERS file entry for XFS.

Move psw_set_key() from ptrace.h to processor.h which is a more
suitable place for it. In addition the moves makes the function
invisible to user space.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

This is mainly to switch off all potentially debugging stuff that
won't report anything useful after an oops happened.
Besided that setting pause_on_oops will work too, but doesn't make
too much sense on s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Print list of modules on die() like a lot of other architectures do.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

WARNING: arch/s390/kernel/built-in.o(.text+0xb92a):
	 Section mismatch: reference to .init.text:start_secondary
	 (between 'restart_addr' and 'stack_overflow')
WARNING: arch/s390/appldata/built-in.o(.data+0xdc):
	 Section mismatch: reference to .init.text:
	 (between 'appldata_nb' and 'appldata_timer_lock')
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Added members for volume number and real memory size to header information.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

When appending the 'cio_ignore' kernel parameter to the command line, a blank
has to be inserted in order to separate 'cio_ignore' from the preceding kernel
parameters.
Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Make the git repository bare and so give it the conventional .git suffix.
Signed-off-by: Tim Shimmin <tes@sgi.com>

SGI-PV: 957103
SGI-Modid: xfs-linux-melb:xfs-kern:28678a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>

The old snd-powermac driver has some serious refcounting issues when
initialisation fails, which is the case on all new machines with
a layout-id since those are handled by the new snd-aoa driver.

Some of those bugs seem to have been under the radar for some time
(like double pci_dev_put), but one was actually added in 2.6.22 with
Stephen attempt at teaching refcounting to the driver which didn't
do it at all.

This patch fixes both, thus removing all sort of kref errors that
would happen if that driver gets loaded on a G5 machine or a recent
PowerBook due to OF nodes left around with a 0 refcount.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

The current implementation only handles -ERESTARTNOHAND, whereas we
also need to handle -ERESTART_RESTARTBLOCK in the handle_signal()
case for restartable system calls. Follows the sh change.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

The current implementation only handles -ERESTARTNOHAND, whereas we
also need to handle -ERESTART_RESTARTBLOCK in the handle_signal()
case for restartable system calls.

As noted by Carl:

This fixes the LTP test nanosleep03 - the current kernel causes
-ERESTART_RESTARTBLOCK to reach user space rather than the correct
-EINTR.
Reported-by: Carl Shaw <shaw.carl@gmail.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

Miklos Szeredi reported very long pauses (several seconds, sometimes
more) on his T60 (with a Core2Duo) which he managed to track down to
wait_task_inactive()'s open-coded busy-loop.

He observed that an interrupt on one core tries to acquire the
runqueue-lock but does not succeed in doing so for a very long time -
while wait_task_inactive() on the other core loops waiting for the first
core to deschedule a task (which it wont do while spinning in an
interrupt handler).

This rewrites wait_task_inactive() to do all its waiting optimistically
without any locks taken at all, and then just double-check the end
result with the proper runqueue lock held over just a very short
section.  If there were races in the optimistic wait, of a preemption
event scheduled the process away, we simply re-synchronize, and start
over.

So the code now looks like this:

	repeat:
		/* Unlocked, optimistic looping! */
		rq = task_rq(p);
		while (task_running(rq, p))
			cpu_relax();

		/* Get the *real* values */
		rq = task_rq_lock(p, &flags);
		running = task_running(rq, p);
		array = p->array;
		task_rq_unlock(rq, &flags);

		/* Check them.. */
		if (unlikely(running)) {
			cpu_relax();
			goto repeat;
		}

		/* Preempted away? Yield if so.. */
		if (unlikely(array)) {
			yield();
			goto repeat;
		}

Basically, that first "while()" loop is done entirely without any
locking at all (and doesn't check for the case where the target process
might have been preempted away), and so it's possibly "incorrect", but
we don't really care.  Both the runqueue used, and the "task_running()"
check might be the wrong tests, but they won't oops - they just mean
that we could possibly get the wrong results due to lack of locking and
exit the loop early in the case of a race condition.

So once we've exited the loop, we then get the proper (and careful) rq
lock, and check the running/runnable state _safely_.  And if it turns
out that our quick-and-dirty and unsafe loop was wrong after all, we
just go back and try it all again.

(The patch also adds a lot of comments, which is the actual bulk of it
all, to make it more obvious why we can do these things without holding
the locks).

Thanks to Miklos for all the testing and tracking it down.
Tested-by: Miklos Szeredi <miklos@szeredi.hu>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Gene Heskett reported the following problem while testing CFS: SysRq-N
is not always effective in normalizing tasks back to SCHED_OTHER.

The reason for that turns out to be the following bug:

 - normalize_rt_tasks() uses for_each_process() to iterate through all
   tasks in the system.  The problem is, this method does not iterate
   through all tasks, it iterates through all thread groups.

The proper mechanism to enumerate over all threads is to use a
do_each_thread() + while_each_thread() loop.
Reported-by: Gene Heskett <gene.heskett@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

* master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6:
  [SCSI] ESP: Don't forget to clear ESP_FLAG_RESETTING.
  [SCSI] fusion: fix for BZ 8426 - massive slowdown on SCSI CD/DVD drive

Don't let signalfd dequeue private signals off other threads (in the
case of things like SIGILL or SIGSEGV, trying to do so would result
in undefined behaviour on who actually gets the signal, since they
are force unblocked).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>