Commit Graph

98153 Commits

Author SHA1 Message Date
Yoichi Yuasa f1304b358a [MIPS] Vr41xx: Initialize PCI io_map_base
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Ralf Baechle b8157180cc [MIPS] Malta: Always compile MTD platform device registration code.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Thomas Bogendoerfer 938b2b1417 [MIPS] Malta: Fix build errors for 64-bit kernels
Fix 64-bit Malta by using CKSEG0ADDR and correct casts.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Thomas Horsten 1f34f2e426 [MIPS] Lasat: sysctl fixup
LASAT's sysctl interface was broken, it failed a check during boot because
a single entry had a sysctl number and the rest were unnumbered. When I
fixed it I noticed that the whole sysctl file needed a spring clean, it was
using mutexes where it wasn't needed (it's only needed to protect during
writes to the EEPROM), so I moved that stuff out and generally cleaned the
whole thing up.

So now, LASAT's sysctl/proc interface is working again.

Signed-off-by: Thomas Horsten <thomas@horsten.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Ralf Baechle c9c5023d83 [MIPS] Fix buggy use of kmap_coherent.
Assuming the call of kmap_coherent in local_r4k_flush_cache_page doesn't
need fixing this was skipped in fcae549295bcae801ac48fc1c2030ab8cc487020.
Turns out it needed the same change after all.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Thomas Horsten 0c3bd83b09 [MIPS] Lasat: bring back from the dead
After the common MIPS CPU interrupt controller (for irq0-7) was introduced
the Lasat boards didn't get their interrupts right, so nothing worked. The
old routines need to be offset by the new 8 hardware interrupts common to
all MIPS CPU's.

Signed-off-by: Thomas Horsten <thomas@horsten.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Chris Dearman d6c3048cad [MIPS] vpe_id is required for VSMP and SMTC builds
Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:48 +01:00
Zenon Fortuna a9ad02bdbb [MIPS] Export smp_call_function and smp_call_function_single.
Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:47 +01:00
Maciej W. Rozycki 461a082f87 [MIPS] Bring the SWARM defconfig up to date
The SWARM defconfig file has not been regenerated for over a year now.
Here is a patch to bring the file up to date.  Additionally some important
and sometimes confusing changes happened meanwhile.  Here is the list of
notable corresponding updates to the configuration:

1. CPU_SB1_PASS_2_2 is now selected rather than CPU_SB1_PASS_1.  The
   latter requires a non-standard -msb1-pass1-workarounds option to be
   supported by GCC and I am told is quite rare anyway.

   [Ralf: Afaik -msb1-pass1-workarounds is available only in Monta Vista's
   special Sibyte gcc 3.0 variant and gcc 3.0 is too old to build a modern
   kernel anyway.]

2. PHYLIB and BROADCOM_PHY are both built in and NETDEV_1000 enabled as
   required by SB1250_MAC.

3. USB and USB_OHCI_HCD are enabled as there is an OHCI chip onboard.

4. TMPFS is enabled, because I use it. ;-)

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:47 +01:00
Maciej W. Rozycki 63a4881a7d [MIPS] Sibyte: Build RTC support as an object
Build the SWARM platform library is as an object rather than an archive
so that files which only contain symbols used by initcalls and do not
provide any symbols that would pull them from an archive still work.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:47 +01:00
Atsushi Nemoto 7bd0fea2c5 [MIPS] Fix the fix for divide by zero error in build_{clear,copy}_page
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:47 +01:00
Ralf Baechle 89052bd7b3 [MIPS] Fix build for PNX platforms.
Build error was caused by commit 351336929c.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:47 +01:00
Thomas Bogendoerfer 330117ff27 [MIPS] Add RM200 with R5000 CPU to known ARC machines
RM200 with R5ks have a little bit different arcname.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:46 +01:00
Thomas Bogendoerfer 0e27d79311 [MIPS] Better load address for big endian SNI RM
Use better load address for big endian kernels to avoid clashes with
PROM / SASH.

Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:46 +01:00
Maciej W. Rozycki d0f9cbd4b2 [MIPS] SB1250: Initialize io_map_base
Correctly initialize io_map_base for the SB1250 PCI controller as required
for proper iomap support.  Based on a proposal from Daniel Jacobowitz.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:46 +01:00
bruno randolf 6b7d0b2fb6 [MIPS] Alchemy: Add au1500 reserved interrupt
In the conversion done in the commits

  95c4eb3ef4484ca85da5c98780d358cffd546b90
  9d360ab4a7

  [MIPS] Alchemy: Renumber interrupts so irq_cpu can work.

one reserved interrupt on au1500 was missed. this broke the au1000 ethernet
driver.

Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:46 +01:00
Ralf Baechle 497d2adcbf [MIPS] Export empty_zero_page for sake of the ext4 module.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-06-16 15:14:46 +01:00
Linus Torvalds 066519068a Merge git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6:
  ide-generic: don't probe all legacy ISA IDE ports by default
  ide-cs: fix releasing I/O resources
  ide-cs: fix probing and add warm-plug support
  ide-pmac: remove bogus comment about pmac_ide_setup_device()
  ide-pmac: add ->cable_detect method
  ide-pmac: bugfix for media-bay support rework
  opti621: add PIO 4 support
  opti621: use pre-calculated PIO timings
  opti621: program devices timings separately in ->set_pio_mode
  opti621: use PCI clock value provided by controller
  opti621: remove DMA support
  opti621: disable read prefetch
2008-06-15 16:53:33 -07:00
Mark McLoughlin b92dea67cc virtio: Complete feature negotation before updating status
lguest (in rusty's use-tun-ringfd patch) assumes that the
guest has updated its feature bits before setting its status
to VIRTIO_CONFIG_S_DRIVER_OK.

That's pretty reasonable, so let's make it so.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-15 13:46:16 -07:00
Bartlomiej Zolnierkiewicz 0cbccbc30a ide-generic: don't probe all legacy ISA IDE ports by default
We can't probe all legacy ISA IDE ports by default as the resources may be
occupied by other ISA devices.  Add "probe_mask" module parameter and probe
only first two ISA IDE ports by default leaving the decision about probing
the rest to the user (systems with ISA ide2-6 should be very, very rare).

This fixes a regression caused by:

commit 343a3451e2
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Tue Jun 10 20:56:36 2008 +0200

    ide-generic: add missing hwif->chipset setup
...

Reported-by: Mikael Pettersson <mikpe@it.uu.se>
Bisected-by: Mikael Pettersson <mikpe@it.uu.se>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:24 +02:00
Bartlomiej Zolnierkiewicz fbc69fd9b7 ide-cs: fix releasing I/O resources
hwif content is already freed after ide_release() call so cache
hwif->io_ports.{data,ctl}_addr in local variables in ide_detach().

This fixes post-2.6.25 regression.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:23 +02:00
Bartlomiej Zolnierkiewicz 792a1a9856 ide-cs: fix probing and add warm-plug support
* Fix probing by using ide_port_scan() and moving "retry loop"
  from ide_config() to idecs_register().

* Don't fail probe if there are no devices attached to a port.

* Remove (now redundant) error message from ide_config().

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:23 +02:00
Bartlomiej Zolnierkiewicz 5b16464ac3 ide-pmac: remove bogus comment about pmac_ide_setup_device()
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:23 +02:00
Bartlomiej Zolnierkiewicz 07a6c66da5 ide-pmac: add ->cable_detect method
Add ->cable_detect method and remove no longer needed pmif->cable_80 flag
(there is also no need to mask ->udma_mask now).

This fixes:

- forced ignoring of cable detection (needed for some CF devices & debug)

- cable detection for warm-plug

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:23 +02:00
Bartlomiej Zolnierkiewicz c1a8e39819 ide-pmac: bugfix for media-bay support rework
Fix bug introduced by:

commit 2dde7861af
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Fri Apr 18 00:46:23 2008 +0200

    ide: rework PowerMac media-bay support (take 2)
...

[ Yeah, I suck. ]

bay->cd_index shouldn't be changed if IDE devices are not present
or retry operations won't happen.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:23 +02:00
Bartlomiej Zolnierkiewicz 80a65fc5ee opti621: add PIO 4 support
* Add PIO 4 support.

While at it:

* Use a single struct ide_port_info instance for OPTi621 and OPTi621X.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:22 +02:00
Bartlomiej Zolnierkiewicz 810253d44b opti621: use pre-calculated PIO timings
* Use pre-calculated PIO timings in ->set_pio_mode.

* Remove no longer needed compute_clocks(), cmpt_clk(), struct pio_clocks_s,
  PIO_* defines and OPTI621_DEBUG define.

There should be no functional changes caused by this patch.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:22 +02:00
Bartlomiej Zolnierkiewicz 6c987183fc opti621: program devices timings separately in ->set_pio_mode
* Set drive->drive_data to 'pio + XFER_PIO_0' instead of 'pio',
  then simplify selecting maximum adress setup timing.

* Remove no longer needed compute_pios() and opti621_port_init_devs().

* Program devices timings separately in ->set_pio_mode.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:22 +02:00
Bartlomiej Zolnierkiewicz 21bd33a656 opti621: use PCI clock value provided by controller
Use PCI clock value provided by controller instead of depending on
a default (or user supplied) value.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:22 +02:00
Bartlomiej Zolnierkiewicz f361037631 opti621: remove DMA support
These controllers don't support DMA.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:21 +02:00
Bartlomiej Zolnierkiewicz 62128b2ca8 opti621: disable read prefetch
This fixes 2.6.25 regression (kernel.org bugzilla bug #10723) caused by:

commit 912fb29a36
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Fri Oct 19 00:30:11 2007 +0200

    opti621: always tune PIO
...

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.

Bisected-by: Juergen Kosel <juergen.kosel@gmx.de>
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
2008-06-15 21:00:21 +02:00
Linus Torvalds 0269c5c6d9 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
  PCI: fixup write combine comment in pci_mmap_resource
  x86: PAT export resource_wc in pci sysfs
  x86, pci-dma.c: don't always add __GFP_NORETRY to gfp
  suspend-vs-iommu: prevent suspend if we could not resume
  x86: pci-dma.c: use __GFP_NO_OOM instead of __GFP_NORETRY
  pci, x86: add workaround for bug in ASUS A7V600 BIOS (rev 1005)
  PCI: use dev_to_node in pci_call_probe
  PCI: Correct last two HP entries in the bfsort whitelist
2008-06-14 13:32:56 -07:00
Linus Torvalds 7775c9753b Merge git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  parisc: update my email address
  parisc: fix miscompilation of ip_fast_csum with gcc >= 4.3
  parisc: fix off by one in setup_sigcontext32
  parisc: export empty_zero_page
  parisc: export copy_user_page_asm
  parisc: move head.S to head.text section
  Revert "parisc: fix trivial section name warnings"
2008-06-13 09:47:07 -07:00
Kyle McMartin 42a5a8a60a parisc: update my email address
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:57 -04:00
Kyle McMartin e374d17cd7 parisc: fix miscompilation of ip_fast_csum with gcc >= 4.3
ip_fast_csum needs an asm "memory" clobber, otherwise the aggressive
optimizations in gcc-4.3 cause it to be miscompiled.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:56 -04:00
Kyle McMartin f4441b62d4 parisc: fix off by one in setup_sigcontext32
Thankfully, the values were irrelevant... Spotted by
newer gcc.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:55 -04:00
Kyle McMartin 22febf1f37 parisc: export empty_zero_page
Needed by ext4 when built as a module.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:53 -04:00
Kyle McMartin db51d92b90 parisc: export copy_user_page_asm
Needed by fuse (via copy_highpage).

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:50 -04:00
Kyle McMartin 1138a72cd9 parisc: move head.S to head.text section
And explicitly list it in vmlinux.lds...

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:47 -04:00
Kyle McMartin dfcf753bd3 Revert "parisc: fix trivial section name warnings"
This reverts commit bd3bb8c15b.

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
2008-06-13 10:49:45 -04:00
Linus Torvalds fa8d84b78b Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
  ahci: Workaround HW bug for SB600/700 SATA controller PMP support
  ahci: workarounds for mcp65
2008-06-13 07:40:57 -07:00
Linus Torvalds 51558576ea Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  tcp: Revert 'process defer accept as established' changes.
  ipv6: Fix duplicate initialization of rawv6_prot.destroy
  bnx2x: Updating the Maintainer
  net: Eliminate flush_scheduled_work() calls while RTNL is held.
  drivers/net/r6040.c: correct bad use of round_jiffies()
  fec_mpc52xx: MPC52xx_MESSAGES_DEFAULT: 2nd NETIF_MSG_IFDOWN => IFUP
  ipg: fix receivemode IPG_RM_RECEIVEMULTICAST{,HASH} in ipg_nic_set_multicast_list()
  netfilter: nf_conntrack: fix ctnetlink related crash in nf_nat_setup_info()
  netfilter: Make nflog quiet when no one listen in userspace.
  ipv6: Fail with appropriate error code when setting not-applicable sockopt.
  ipv6: Check IPV6_MULTICAST_LOOP option value.
  ipv6: Check the hop limit setting in ancillary data.
  ipv6 route: Fix route lifetime in netlink message.
  ipv6 mcast: Check address family of gf_group in getsockopt(MS_FILTER).
  dccp: Bug in initial acknowledgment number assignment
  dccp ccid-3: X truncated due to type conversion
  dccp ccid-3: TFRC reverse-lookup Bug-Fix
  dccp ccid-2: Bug-Fix - Ack Vectors need to be ignored on request sockets
  dccp: Fix sparse warnings
  dccp ccid-3: Bug-Fix - Zero RTT is possible
2008-06-13 07:34:47 -07:00
Linus Torvalds d36e311070 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc: get leo framebuffer working
2008-06-13 07:34:01 -07:00
Shane Huang bd17243a84 ahci: Workaround HW bug for SB600/700 SATA controller PMP support
There is one bug in ATI SATA PMP of SB600 and SB700 old revision, which leads
to soft reset failure. This patch can fix the bug.

Signed-off-by: Shane Huang <shane.huang@amd.com>
Acked-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
2008-06-13 02:46:55 -04:00
Tejun Heo e297d99e10 ahci: workarounds for mcp65
MCP65 ahci can do NCQ but doesn't set the CAP bit and rev A0 and A1
can't do MSI but have MSI capability.  Implement AHCI_HFLAG_YES_NCQ
and apply appropriate workarounds.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
2008-06-13 02:46:17 -04:00
Linus Torvalds 61d6cc5489 Merge master.kernel.org:/home/rmk/linux-2.6-arm
* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] 5091/1: Add missing bitfield include to regs-lcd.h
  [ARM] 5090/1: Correct pxafb palette typo error
  [ARM] 5077/1: spi: fix list scan success verification in PXA ssp driver
2008-06-12 19:37:29 -07:00
Sergey Lapin c6d8f400cc rtc: Ramtron FM3130 RTC support
Ramtron FM3130 is a chip with two separate devices inside, RTC clock and
FRAM.  This driver provides only RTC functionality.

This chip is met in lots of custom boards with AT91SAMXXXX CPU I work
with, is cheap and in no way better or worse than any other RTC on market.
 While it is mostly met on much smaller devices, I think it is great to
have it supported in Linux.

Signed-off-by: Sergey Lapin <slapin@ossfans.org>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-12 18:05:42 -07:00
David Brownell e6d2bb2bac rtc: make HPET_RTC_IRQ track HPET_EMULATE_RTC
More Kconfig tweaks related to the legacy PC RTC code:

 - Describe the legacy PC RTC driver as such ... it's never quite
   been clear that this driver is for PC RTCs, and now it's fair
   to call this the "legacy" driver.

 - Force it to understand about HPET stealing its IRQs ... kernel
   code does this always when HPET is in use, there should be no
   option for users to goof up the config.

This seems to fix kernel bugzilla #10729.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-12 18:05:42 -07:00
Stas Sergeev 1da2e3d679 provide rtc_cmos platform device
Recently (around 2.6.25) I've noticed that RTC no longer works for me.  It
turned out this is because I use pnpacpi=off kernel option to work around
the parport_pc bugs.  I always did so, but RTC used to work fine in the
past, and now it have regressed.

The patch fixes the problem by creating the platform device for the RTC
when PNP is disabled.  This may also help running the PNP-enabled kernel
on an older PCs.

Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Cc: David Brownell <david-b@pacbell.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Adam Belay <ambx1@neo.rr.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-12 18:05:42 -07:00
Nick Piggin 643b52b9c0 radix-tree: fix small lockless radix-tree bug
We shrink a radix tree when its root node has only one child, in the left
most slot.  The child becomes the new root node.  To perform this
operation in a manner compatible with concurrent lockless lookups, we
atomically switch the root pointer from the parent to its child.

However a concurrent lockless lookup may now have loaded a pointer to the
parent (and is presently deciding what to do next).  For this reason, we
also have to keep the parent node in a valid state after shrinking the
tree, until the next RCU grace period -- otherwise this lookup with the
parent pointer may not do the right thing.  Notably, we need to keep the
child in the left most slot there in case that is requested by the lookup.

This is all pretty standard RCU stuff.  It is worth repeating because in
my eagerness to obey the radix tree node constructor scheme, I had broken
it by zeroing the radix tree node before the grace period.

What could happen is that a lookup can load the parent pointer, then
decide it wants to follow the left most child slot, only to find the slot
contained NULL due to the concurrent shrinker having zeroed the parent
node before waiting for a grace period.  The lookup would return a false
negative as a result.

Fix it by doing that clearing in the RCU callback.  I would normally want
to rip out the constructor entirely, but radix tree nodes are one of those
places where they make sense (only few cachelines will be touched soon
after allocation).

This was never actually found in any lockless pagecache testing or by the
test harness, but by seeing the odd problem with my scalable vmap rewrite.
 I have not tickled the test harness into reproducing it yet, but I'll
keep working at it.

Fortunately, it is not a problem anywhere lockless pagecache is used in
mainline kernels (pagecache probe is not a guarantee, and brd does not
have concurrent lookups and deletes).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-06-12 18:05:41 -07:00