Now that powerpc runs irq_exit() under the irq stack,
let the softirq core know about that so that we spare
the needless stack switch on irq exit's softirq processing.
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

x86-64 runs irq_exit() under the irq stack. So it can afford
to run softirqs in hardirq exit without the need to switch
the stacks. The hardirq stack is good enough for that.

Now x86-64 runs softirqs in the hardirq stack anyway, so what we
mostly skip is some needless per cpu refcounting updates there.

x86-32 is not concerned because it only runs the irq handler on
the irq stack.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

If irq_exit() is called on the arch's specified irq stack,
it should be safe to run softirqs inline under that same
irq stack as it is near empty by the time we call irq_exit().

For example if we use the same stack for both hard and soft irqs here,
the worst case scenario is:
hardirq -> softirq -> hardirq. But then the softirq supersedes the
first hardirq as the stack user since irq_exit() is called in
a mostly empty stack. So the stack merge in this case looks acceptable.

Stack overrun still have a chance to happen if hardirqs have more
opportunities to nest, but then it's another problem to solve.

So lets adapt the irq exit's softirq stack on top of a new Kconfig symbol
that can be defined when irq_exit() runs on the irq stack. That way
we can spare some stack switch on irq processing and all the cache
issues that come along.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

For clarity, comment the various stack choices for softirqs
processing, whether we execute them from ksoftirqd or
local_irq_enable() calls.

Their use on irq_exit() is already commented.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

do_softirq() has a debug check that verifies that it is not nesting
on softirqs processing, nor miscounting the softirq part of the preempt
count.

But making sure that softirqs processing don't nest is actually a more
generic concern that applies to any caller of __do_softirq().

Do take it one step further and generalize that debug check to
any softirq processing.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

Before processing softirqs on hardirq exit, we already
do the check for pending softirqs while hardirqs are
guaranteed to be disabled.

So we can take a shortcut and safely jump to the arch
specific implementation directly.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

All arch overriden implementations of do_softirq() share the following
common code: disable irqs (to avoid races with the pending check),
check if there are softirqs pending, then execute __do_softirq() on
a specific stack.

Consolidate the common parts such that archs only worry about the
stack switch.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

The commit facd8b80
("irq: Sanitize invoke_softirq") converted irq exit
calls of do_softirq() to __do_softirq() on all architectures,
assuming it was only used there for its irq disablement
properties.

But as a side effect, the softirqs processed in the end
of the hardirq are always called on the inline current
stack that is used by irq_exit() instead of the softirq
stack provided by the archs that override do_softirq().

The result is mostly safe if the architecture runs irq_exit()
on a separate irq stack because then softirqs are processed
on that same stack that is near empty at this stage (assuming
hardirq aren't nesting).

Otherwise irq_exit() runs in the task stack and so does the softirq
too. The interrupted call stack can be randomly deep already and
the softirq can dig through it even further. To add insult to the
injury, this softirq can be interrupted by a new hardirq, maximizing
the chances for a stack overrun as reported in powerpc for example:

	do_IRQ: stack overflow: 1920
	CPU: 0 PID: 1602 Comm: qemu-system-ppc Not tainted 3.10.4-300.1.fc19.ppc64p7 #1
	Call Trace:
	[c0000000050a8740] .show_stack+0x130/0x200 (unreliable)
	[c0000000050a8810] .dump_stack+0x28/0x3c
	[c0000000050a8880] .do_IRQ+0x2b8/0x2c0
	[c0000000050a8930] hardware_interrupt_common+0x154/0x180
	--- Exception: 501 at .cp_start_xmit+0x3a4/0x820 [8139cp]
		LR = .cp_start_xmit+0x390/0x820 [8139cp]
	[c0000000050a8d40] .dev_hard_start_xmit+0x394/0x640
	[c0000000050a8e00] .sch_direct_xmit+0x110/0x260
	[c0000000050a8ea0] .dev_queue_xmit+0x260/0x630
	[c0000000050a8f40] .br_dev_queue_push_xmit+0xc4/0x130 [bridge]
	[c0000000050a8fc0] .br_dev_xmit+0x198/0x270 [bridge]
	[c0000000050a9070] .dev_hard_start_xmit+0x394/0x640
	[c0000000050a9130] .dev_queue_xmit+0x428/0x630
	[c0000000050a91d0] .ip_finish_output+0x2a4/0x550
	[c0000000050a9290] .ip_local_out+0x50/0x70
	[c0000000050a9310] .ip_queue_xmit+0x148/0x420
	[c0000000050a93b0] .tcp_transmit_skb+0x4e4/0xaf0
	[c0000000050a94a0] .__tcp_ack_snd_check+0x7c/0xf0
	[c0000000050a9520] .tcp_rcv_established+0x1e8/0x930
	[c0000000050a95f0] .tcp_v4_do_rcv+0x21c/0x570
	[c0000000050a96c0] .tcp_v4_rcv+0x734/0x930
	[c0000000050a97a0] .ip_local_deliver_finish+0x184/0x360
	[c0000000050a9840] .ip_rcv_finish+0x148/0x400
	[c0000000050a98d0] .__netif_receive_skb_core+0x4f8/0xb00
	[c0000000050a99d0] .netif_receive_skb+0x44/0x110
	[c0000000050a9a70] .br_handle_frame_finish+0x2bc/0x3f0 [bridge]
	[c0000000050a9b20] .br_nf_pre_routing_finish+0x2ac/0x420 [bridge]
	[c0000000050a9bd0] .br_nf_pre_routing+0x4dc/0x7d0 [bridge]
	[c0000000050a9c70] .nf_iterate+0x114/0x130
	[c0000000050a9d30] .nf_hook_slow+0xb4/0x1e0
	[c0000000050a9e00] .br_handle_frame+0x290/0x330 [bridge]
	[c0000000050a9ea0] .__netif_receive_skb_core+0x34c/0xb00
	[c0000000050a9fa0] .netif_receive_skb+0x44/0x110
	[c0000000050aa040] .napi_gro_receive+0xe8/0x120
	[c0000000050aa0c0] .cp_rx_poll+0x31c/0x590 [8139cp]
	[c0000000050aa1d0] .net_rx_action+0x1dc/0x310
	[c0000000050aa2b0] .__do_softirq+0x158/0x330
	[c0000000050aa3b0] .irq_exit+0xc8/0x110
	[c0000000050aa430] .do_IRQ+0xdc/0x2c0
	[c0000000050aa4e0] hardware_interrupt_common+0x154/0x180
	 --- Exception: 501 at .bad_range+0x1c/0x110
		 LR = .get_page_from_freelist+0x908/0xbb0
	[c0000000050aa7d0] .list_del+0x18/0x50 (unreliable)
	[c0000000050aa850] .get_page_from_freelist+0x908/0xbb0
	[c0000000050aa9e0] .__alloc_pages_nodemask+0x21c/0xae0
	[c0000000050aaba0] .alloc_pages_vma+0xd0/0x210
	[c0000000050aac60] .handle_pte_fault+0x814/0xb70
	[c0000000050aad50] .__get_user_pages+0x1a4/0x640
	[c0000000050aae60] .get_user_pages_fast+0xec/0x160
	[c0000000050aaf10] .__gfn_to_pfn_memslot+0x3b0/0x430 [kvm]
	[c0000000050aafd0] .kvmppc_gfn_to_pfn+0x64/0x130 [kvm]
	[c0000000050ab070] .kvmppc_mmu_map_page+0x94/0x530 [kvm]
	[c0000000050ab190] .kvmppc_handle_pagefault+0x174/0x610 [kvm]
	[c0000000050ab270] .kvmppc_handle_exit_pr+0x464/0x9b0 [kvm]
	[c0000000050ab320]  kvm_start_lightweight+0x1ec/0x1fc [kvm]
	[c0000000050ab4f0] .kvmppc_vcpu_run_pr+0x168/0x3b0 [kvm]
	[c0000000050ab9c0] .kvmppc_vcpu_run+0xc8/0xf0 [kvm]
	[c0000000050aba50] .kvm_arch_vcpu_ioctl_run+0x5c/0x1a0 [kvm]
	[c0000000050abae0] .kvm_vcpu_ioctl+0x478/0x730 [kvm]
	[c0000000050abc90] .do_vfs_ioctl+0x4ec/0x7c0
	[c0000000050abd80] .SyS_ioctl+0xd4/0xf0
	[c0000000050abe30] syscall_exit+0x0/0x98

Since this is a regression, this patch proposes a minimalistic
and low-risk solution by blindly forcing the hardirq exit processing of
softirqs on the softirq stack. This way we should reduce significantly
the opportunities for task stack overflow dug by softirqs.

Longer term solutions may involve extending the hardirq stack coverage to
irq_exit(), etc...
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: #3.9.. <stable@vger.kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@au1.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Andrew Morton <akpm@linux-foundation.org>

Pull USB fixes from Greg KH:
 "Here are a number of USB driver fixes for 3.12-rc3.

  These are all for host controller issues that have been reported, and
  there's a fix for an annoying error message that gets printed every
  time you remove a USB 3 device from the system that's been bugging me
  for a while"

* tag 'usb-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: dwc3: add support for Merrifield
  USB: fsl/ehci: fix failure of checking PHY_CLK_VALID during reinitialization
  USB: Fix breakage in ffs_fs_mount()
  fsl/usb: Resolve PHY_CLK_VLD instability issue for ULPI phy
  usb/core/devio.c: Don't reject control message to endpoint with wrong direction bit
  usb: chipidea: USB_CHIPIDEA should depend on HAS_DMA
  usb: chipidea: udc: free pending TD at removal procedure
  usb: chipidea: imx: Add usb_phy_shutdown at probe's error path
  usb: chipidea: Fix memleak for ci->hw_bank.regmap when removal
  usb: chipidea: udc: fix the oops after rmmod gadget
  USB: fix PM config symbol in uhci-hcd, ehci-hcd, and xhci-hcd
  USB: OHCI: accept very late isochronous URBs
  USB: UHCI: accept very late isochronous URBs
  USB: iMX21: accept very late isochronous URBs
  usbcore: check usb device's state before sending a Set SEL control transfer
  xhci: Fix race between ep halt and URB cancellation
  usb: Fix xHCI host issues on remote wakeup.
  xhci: Ensure a command structure points to the correct trb on the command ring
  xhci: Fix oops happening after address device timeout

Pull tty/serial fixes from Greg KH:
 "Here are some serial at tty driver fixes for 3.12-rc3

  The serial driver fixes some kref leaks, documentation is moved to the
  proper places, and the tty and n_tty fixes resolve some reported
  regressions.  There is still one outstanding tty regression fix that
  isn't in here yet, as I want to test it out some more, it will be sent
  for 3.12-rc4 if it checks out"

* tag 'tty-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: ar933x_uart: move devicetree binding documentation
  tty: Fix SIGTTOU not sent with tcflush()
  n_tty: Fix EOF push index when termios changes
  serial: pch_uart: remove unnecessary tty_port_tty_get
  serial: pch_uart: fix tty-kref leak in dma-rx path
  serial: pch_uart: fix tty-kref leak in rx-error path
  serial: tegra: fix tty-kref leak

Pull staging fixes from Greg KH:
 "Here are some staging driver fixes, MAINTAINER updates, and a new
  device id.  All of these have been in the linux-next tree, and are
  pretty simple patches"

* tag 'staging-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: r8188eu: Add new device ID
  staging: imx-drm: Fix probe failure
  staging: vt6656: [BUG] iwctl_siwencodeext return if device not open
  staging: vt6656: [BUG] main_usb.c oops on device_close move flag earlier.
  staging: vt6656: rxtx.c [BUG] s_vGetFreeContext dead lock on null apTD.
  Staging: rtl8192u: r819xU_cmdpkt: checking NULL value after doing dev_alloc_skb
  staging: usbip: Orphan usbip
  staging: r8188eu: Add files for new drive: Cocci spatch "noderef"
  staging: r8188eu: Cocci spatch "noderef"
  staging: octeon-usb: Cocci spatch "noderef"
  staging: r8188eu: Add files for new drive: Cocci spatch "noderef"
  MAINTAINERS: staging: dgnc and dgap drivers: add maintainer
  staging: lustre: Cocci spatch "noderef"

Merge tag 'driver-core-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core / sysfs fixes from Greg KH:
 "Here are 2 fixes for 3.12-rc3.  One fixes a sysfs problem with
  mounting caused by 3.12-rc1, and the other is a bug reported by the
  chromeos developers with the driver core.

  Both have been in linux-next for a bit"

* tag 'driver-core-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  driver core : Fix use after free of dev->parent in device_shutdown
  sysfs: Allow mounting without CONFIG_NET

Pull char/misc driver fixes from Greg KH:
 "Here are some HyperV and MEI driver fixes for 3.12-rc3.  They resolve
  some issues that people have been reporting for them"

* tag 'char-misc-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Drivers: hv: vmbus: Terminate vmbus version negotiation on timeout
  Drivers: hv: util: Correctly support ws2008R2 and earlier
  mei: cancel stall timers in mei_reset
  mei: bus: stop wait for read during cl state transition
  mei: make me client counters less error prone

Pull perf revert from Ingo Molnar:
 "This fixes the 'perf top' regression Markus Trippelsdorf reported"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "perf symbols: Demangle cloned functions"

Pull drm fixes from Dave Airlie:
 "Nothing too major, radeon still has some dpm changes for off by
  default.

  Radeon, intel, msm:
   - radeon: a few more dpm fixes (still off by default), uvd fixes
   - i915: runtime warn backtrace and regression fix
   - msm: iommu changes fallout"

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (27 commits)
  drm/msm: use drm_gem_dumb_destroy helper
  drm/msm: deal with mach/iommu.h removal
  drm/msm: Remove iommu include from mdp4_kms.c
  drm/msm: Odd PTR_ERR usage
  drm/i915: Fix up usage of SHRINK_STOP
  drm/radeon: fix hdmi audio on DCE3.0/3.1 asics
  drm/i915: preserve pipe A quirk in i9xx_set_pipeconf
  drm/i915/tv: clear adjusted_mode.flags
  drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER
  drm/radeon/cik: fix overflow in vram fetch
  drm/radeon: add missing hdmi callbacks for rv6xx
  drm/i915: Use a temporary va_list for two-pass string handling
  drm/radeon/uvd: lower msg&fb buffer requirements on UVD3
  drm/radeon: disable tests/benchmarks if accel is disabled
  drm/radeon: don't set default clocks for SI when DPM is disabled
  drm/radeon/dpm/ci: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/si: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/ni: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/btc: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm: fetch the max clk from voltage dep tables helper
  ...

This reverts commit de95ab53.

Markus Trippelsdorf reported that this commit broke 'perf top':

 > I just see a gray screen with no text at all. Sometimes the
 > following error messages are printed:
 >
 >  *** Error in `perf': invalid fastbin entry (free): 0x00000000029b18c0
 >  ***
 >  *** Error in `perf': malloc(): memory corruption (fast): 0x0000000000ee0b10 ***

While this code is fixable, the commit itself fails on several levels:

 - it should have been a separate helper function
 - why the heck does it do strchr() twice
 - it casts a const char * over into char *
 - sloppy style
 - it's not even a regression fix!

So lets revert it and re-try the patch in v3.13.
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

A small fix + deal with fallout of iommu changes + use new
drm_gem_dumb_destroy helper.

* 'msm-fixes-3.12-rc2' of git://people.freedesktop.org/~robclark/linux:
  drm/msm: use drm_gem_dumb_destroy helper
  drm/msm: deal with mach/iommu.h removal
  drm/msm: Remove iommu include from mdp4_kms.c
  drm/msm: Odd PTR_ERR usage

Merge branches 'sched-urgent-for-linus', 'timers-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler, timer and x86 fixes from Ingo Molnar:
 - A context tracking ARM build and functional fix
 - A handful of ARM clocksource/clockevent driver fixes
 - An AMD microcode patch level sysfs reporting fixlet

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arm: Fix build error with context tracking calls

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource: em_sti: Set cpu_possible_mask to fix SMP broadcast
  clocksource: of: Respect device tree node status
  clocksource: exynos_mct: Set IRQ affinity when the CPU goes online
  arm: clocksource: mvebu: Use the main timer as clock source from DT

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode/AMD: Fix patch level reporting for family 15h

Pull perf fixes from Ingo Molnar:
 "A couple of tooling fixlets and a PMU detection printout fix"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86: Fix PMU detection printout when no PMU is detected
  perf symbols: Demangle cloned functions
  perf machine: Fix path unpopulated in machine__create_modules()
  perf tools: Explicitly add libdl dependency
  perf probe: Fix probing symbols with optimization suffix
  perf trace: Add mmap2 handler
  perf kmem: Make it work again on non NUMA machines

Pull xfs bugfixes from Ben Myers:
 - fix for directory node collapse regression
 - fix for recovery over stale on disk structures
 - fix for eofblocks ioctl
 - fix asserts in xfs_inode_free
 - lock the ail before removing an item from it

* tag 'xfs-for-linus-v3.12-rc3' of git://oss.sgi.com/xfs/xfs:
  xfs: fix node forward in xfs_node_toosmall
  xfs: log recovery lsn ordering needs uuid check
  xfs: fix XFS_IOC_FREE_EOFBLOCKS definition
  xfs: asserting lock not held during freeing not valid
  xfs: lock the AIL before removing the buffer item

Pull i2c fixes from Wolfram Sang:
 "Some driver bugfixes for the I2C subsystem"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: ismt: initialize DMA buffer
  i2c: designware: 10-bit addressing mode enabling if I2C_DYNAMIC_TAR_UPDATE is set
  i2c: mv64xxx: Do not use writel_relaxed()
  i2c: mv64xxx: Fix some build warnings
  i2c: s3c2410: fix clk_disable/clk_unprepare WARNings

Pull ACPI and power management fixes from Rafael Wysocki:
 "These fix one recent cpufreq regression, a few older bugs that may
  harm users and a kerneldoc typo.

  Specifics:

   1) After the recent locking changes in the cpufreq core it is
      possible to trigger BUG_ON(!policy) in lock_policy_rwsem_read() if
      cpufreq_get() is called before registering a cpufreq driver.  Fix
      from Viresh Kumar.

   2) If intel_pstate has been loaded already, it doesn't make sense to
      do anything in acpi_cpufreq_init() and moreover doing something in
      there in that case may be harmful, so make that function return
      immediately if another cpufreq driver is already present.  From
      Yinghai Lu.

   3) The ACPI IPMI driver sometimes attempts to acquire a mutex from
      interrupt context, which can be avoided by replacing that mutex
      with a spinlock.  From Lv Zheng.

   4) A NULL pointer may be dereferenced by the exynos5440 cpufreq
      driver if a memory allocation made by it fails.  Fix from Sachin
      Kamat.

   5) Hanjun Guo's commit fixes a typo in the kerneldoc comment
      documenting acpi_bus_unregister_driver()"

* tag 'pm+acpi-3.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / scan: fix typo in comments of acpi_bus_unregister_driver()
  cpufreq: exynos5440: Fix potential NULL pointer dereference
  cpufreq: check cpufreq driver is valid and cpufreq isn't disabled in cpufreq_get()
  acpi-cpufreq: skip loading acpi_cpufreq after intel_pstate
  ACPI / IPMI: Fix atomic context requirement of ipmi_msg_handler()

Ben Herrenschmidt found that commit 928bea96 ("PCI: Delay enabling
bridges until they're needed") breaks PCI in some powerpc environments.

The reason is that the PCIe port driver will call pci_enable_device() on
the bridge, so the device is enabled, but skips pci_set_master because
pcie_port_auto and no acpi on powerpc.

Because of that, pci_enable_bridge() later on (called as a result of the
child device driver doing pci_enable_device) will see the bridge as
already enabled and will not call pci_set_master() on it.

Fixed by add checking in pci_enable_bridge, and call pci_set_master
if driver skip that.

That will make the code more robot and wade off problem for missing
pci_set_master in drivers.
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull s390 lockref enablement from Heiko Carstens:
 "Enabling the new lockless lockref variant on s390 would have been
  trivial until Tony Luck added a cpu_relax() call into the
  CMPXCHG_LOOP(), with commit d472d9d9 ("lockref: Relax in cmpxchg
  loop")

  As already mentioned cpu_relax() is very expensive on s390 since it
  yields() the current virtual cpu.  So we are talking of several
  thousand cycles.  Considering this enabling the lockless lockref
  variant would contradict the intention of the new semantics.  And also
  some quick measurements show performance regressions of 50% and more.

  Simply removing the cpu_relax() call again seems also not very
  desireable since Waiman Long reported that for some workloads the call
  improved performance by 5%."

* 'lockref' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: enable ARCH_USE_CMPXCHG_LOCKREF
  lockref: use arch_mutex_cpu_relax() in CMPXCHG_LOOP()
  mutex: replace CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX with simple ifdef

Commit 6072ddc8 ("kernel: replace strict_strto*() with kstrto*()")
broke the handling of signed integer types, fix it.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Reported-by: Christian Kujau <lists@nerdbynature.de>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull DeviceTree fixes from Rob Herring:
 "Clean-up to fix some warnings for !OF builds and spelling fixes in
  docs:

   - Clean-up openrisc prom.h
   - Fix warnings caused by of_irq.h ifdefs
   - Spelling fix for Synopsys"

* tag 'devicetree-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  dts: Fix misspelling of Synopsys
  of: clean-up ifdefs in of_irq.h
  openrisc: clean-up prom.h

Pull ARM fixes from Russell King:
 "Just a few relatively small ARM fixes found since the last merge
  window, nothing too exciting"

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7837/3: fix Thumb-2 bug in AES assembler code
  ARM: only allow kernel mode neon with AEABI
  ARM: 7839/1: entry: fix tracing of ARM-private syscalls
  ARM: 7836/1: add __get_user_unaligned/__put_user_unaligned

This patch adds code to initialize the DMA buffer to compensate for
possible hardware data corruption.
Signed-off-by: James Ralston <james.d.ralston@intel.com>
[wsa: changed to use 'sizeof']
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Signed-off-by: Rob Clark <robdclark@gmail.com>

We still need an API exported by msm iommu driver (but not visible in
any public header anymore).  For now, just declare the prototype
ourselves, but when msm iommu driver provides a better option, use that
instead.
Signed-off-by: Rob Clark <robdclark@gmail.com>

Ran into this cryptic PMU bootup log recently:

[    0.124047] Performance Events:
[    0.125000] smpboot: ...

Turns out we print this if no PMU is detected. Fall back to
the right condition so that the following is printed:

[    0.122381] Performance Events: no PMU driver, software events only.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/tip-u2fwaUffakjp0qkpRfqljgsn@git.kernel.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>

The include file has been removed and the file does not
need it anyway, so remove it. Fixes a compile error.
Signed-off-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

The variable priv->kms is not initialized yet.

Found by "scripts/coccinelle/tests/odd_ptr_err.cocci".
PTR_ERR should access the value just tested by IS_ERR.
Signed-off-by: Thomas Meyer <thomas@m3y3r.de>

Enable ARCH_USE_CMPXCHG_LOCKREF since it shows performance improvements
with Linus' simple stat() test case of up to 50% on a 30 cpu system.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Make use of arch_mutex_cpu_relax() so architectures can override the
default cpu_relax() semantics.
This is especially useful for s390, where cpu_relax() means that we
yield() the current (virtual) cpu and therefore is very expensive,
and would contradict the whole purpose of the lockless cmpxchg loop.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Linus suggested to replace

 #ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX
 #define arch_mutex_cpu_relax() cpu_relax()
 #endif

with just a simple

  #ifndef arch_mutex_cpu_relax
  # define arch_mutex_cpu_relax() cpu_relax()
  #endif

to get rid of CONFIG_HAVE_CPU_RELAX_SIMPLE. So architectures can
simply define arch_mutex_cpu_relax if they want an architecture
specific function instead of having to add a select statement in
their Kconfig in addition.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

Merge branch 'context_tracking/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into sched/urgent

Pull context tracking ARM fix from Frederic Weisbecker.
Signed-off-by: Ingo Molnar <mingo@kernel.org>

More radeon fixes for 3.12.  Kind of all over the place: UVD, DPM,
tiling, etc.

* 'drm-fixes-3.12' of git://people.freedesktop.org/~agd5f/linux:
  drm/radeon: fix hdmi audio on DCE3.0/3.1 asics
  drm/radeon/cik: fix overflow in vram fetch
  drm/radeon: add missing hdmi callbacks for rv6xx
  drm/radeon/uvd: lower msg&fb buffer requirements on UVD3
  drm/radeon: disable tests/benchmarks if accel is disabled
  drm/radeon: don't set default clocks for SI when DPM is disabled
  drm/radeon/dpm/ci: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/si: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/ni: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm/btc: filter clocks based on voltage/clk dep tables
  drm/radeon/dpm: fetch the max clk from voltage dep tables helper
  drm/radeon: fix missed variable sized access
  drm/radeon: Make r100_cp_ring_info() and radeon_ring_gfx() safe (v2)
  drm/radeon/cik: Add tiling mode index for 1D tiled depth/stencil surfaces
  drm/radeon/cik: Fix encoding of number of banks in tiling configuration info
  drm/radeon/cik: Fix printing of client name on VM protection fault
  drm/radeon: additional gcc fixes for radeon_atombios.c
  drm/radeon: avoid UVD corruption on AGP cards using GPU gart

Merge tag 'drm-intel-fixes-2013-09-26' of git://people.freedesktop.org/~danvet/drm-intel into drm-fixes

Just a few fixes for regressions and other serious stuff.

Two fix state tracking mismatches, together with an additional patch that
I've submitted to stable (somehow forgotten to tag it) we should have them
fixed now (I hope).

* tag 'drm-intel-fixes-2013-09-26' of git://people.freedesktop.org/~danvet/drm-intel:
  drm/i915: Fix up usage of SHRINK_STOP
  drm/i915: preserve pipe A quirk in i9xx_set_pipeconf
  drm/i915/tv: clear adjusted_mode.flags
  drm/i915/dp: increase i2c-over-aux retry interval on AUX DEFER
  drm/i915: Use a temporary va_list for two-pass string handling