1. 27 Mar, 2006 40 commits
    • Bjorn Helgaas's avatar
      [PATCH] PNP: adjust pnp_register_card_driver() signature: ad1816a · 5f53f4e2
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_card_driver() returns the
      number of devices claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Cc: Jaroslav Kysela <perex@suse.cz>
      Acked-by: default avatarTakashi Iwai <tiwai@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      5f53f4e2
    • Bjorn Helgaas's avatar
      [PATCH] pnp: PNP: adjust pnp_register_driver signature · 982c6094
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.  Returning the count is unreliable because devices may be hot-plugged
      in the future.
      
      This changes the convention to "zero for success, or a negative error value,"
      which matches pci_register_driver(), acpi_bus_register_driver(), and
      platform_driver_register().
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      982c6094
    • Bjorn Helgaas's avatar
      [PATCH] pnp: cs4232: adjust pnp_register_driver signature · 070c6999
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      070c6999
    • Bjorn Helgaas's avatar
      [PATCH] pnp: IRDA: adjust pnp_register_driver signature · 803d0abb
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      803d0abb
    • Bjorn Helgaas's avatar
      [PATCH] pnp: opl3sa2: adjust pnp_register_driver signature · 8c59c4a2
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8c59c4a2
    • Bjorn Helgaas's avatar
      [PATCH] pnp: cs4236: adjust pnp_register_driver signature · ed7cb191
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      ed7cb191
    • Bjorn Helgaas's avatar
      [PATCH] pnp: mpu401: adjust pnp_register_driver signature · f301ae6a
      Bjorn Helgaas authored
      This series of patches removes the assumption that pnp_register_driver()
      returns the number of devices claimed.  Returning the count is unreliable
      because devices may be hot-plugged in the future.  (Many devices don't support
      hot-plug, of course, but PNP in general does.)
      
      This changes the convention to "zero for success, or a negative error value,"
      which matches pci_register_driver(), acpi_bus_register_driver(), and
      platform_driver_register().
      
      If drivers need to know the number of devices, they can count calls to their
      .probe() methods.
      
      This patch:
      
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      f301ae6a
    • Bjorn Helgaas's avatar
      [PATCH] pnp: parport: adjust pnp_register_driver signature · 7597fee3
      Bjorn Helgaas authored
      Remove the assumption that pnp_register_driver() returns the number of devices
      claimed.
      
      parport_pc_init() does nothing with "count", so remove it.  Then nobody uses
      the return value of parport_pc_find_ports(), so make it void.  Finally, update
      pnp_register_driver() usage.
      Signed-off-by: default avatarBjorn Helgaas <bjorn.helgaas@hp.com>
      Cc: Adam Belay <ambx1@neo.rr.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      7597fee3
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: M48T86 driver · 1d98af87
      Alessandro Zummo authored
      Add a driver for the ST M48T86 / Dallas DS12887 RTC.
      
      This is a platform driver.  The platform device must provide I/O routines to
      access the RTC.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Cc: Greg KH <greg@kroah.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      1d98af87
    • Richard Purdie's avatar
      [PATCH] RTC subsystem: SA1100/PXA2XX driver · e842f1c8
      Richard Purdie authored
      Add an RTC subsystem driver for the ARM SA1100/PXA2XX processor RTC.
      Signed-off-by: default avatarRichard Purdie <rpurdie@rpsys.net>
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      e842f1c8
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: EP93XX driver · fd507e2f
      Alessandro Zummo authored
      This patch adds a driver for the RTC embedded in the Cirrus Logic EP93XX
      family of processors.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      fd507e2f
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: RS5C372 driver · 7520b94d
      Alessandro Zummo authored
      RTC class aware driver for the Ricoh RS5C372 chip used, among others, on the
      Synology DS101.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      7520b94d
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: PCF8563 driver · b5a82d62
      Alessandro Zummo authored
      An RTC class aware driver for the Philips PCF8563 RTC and Epson RTC8564 chips.
      
      This chip is used on the Iomega NAS100D.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      b5a82d62
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: DS1672 driver · edf1aaa3
      Alessandro Zummo authored
      Driver for the Dallas/Maxim DS1672 chip, found on the Loft
      (http://www.giantshoulderinc.com).
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      edf1aaa3
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: test device/driver · a95579cd
      Alessandro Zummo authored
      Interrupts can be generated by
      
      echo "alarm|tick|update" >/sys/class/rtc/rtcX/device/irq
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      a95579cd
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: X1205 driver · 1fec7c66
      Alessandro Zummo authored
      A port of the existing x1205 driver under the new RTC subsystem.
      
      It is actually under test within the NSLU2 project
      (http://www.nslu2-linux.org) and it is working quite well.
      
      It is the first driver under this new subsystem and should be used as a guide
      to port other drivers.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      1fec7c66
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: dev interface · e824290e
      Alessandro Zummo authored
      Add the dev interface to the RTC subsystem.
      
      Each RTC will be available under /dev/rtcX .  A symlink from /dev/rtc0 to
      /dev/rtc cab be obtained with the following udev rule:
      
      KERNEL=="rtc0", SYMLINK+="rtc"
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      e824290e
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: proc interface · 728a2947
      Alessandro Zummo authored
      Add the proc interface to the RTC subsystem.
      
      The first RTC driver which registers with the class will be accessible by
      /proc/driver/rtc .
      
      This is required for compatibility with the standard RTC driver and to avoid
      breaking any user space application which may erroneusly rely on this.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      728a2947
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: sysfs interface · c5c3e192
      Alessandro Zummo authored
      This patch adds the sysfs interface to the RTC subsystem.
      
      Each RTC client will have his own entry under /sys/classs/rtc/rtcN .
      
      Within this entry some attributes are exported by the subsystem, like date and
      time.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c5c3e192
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: I2C driver ids · f7f3682f
      Alessandro Zummo authored
      This patch adds the I2C driver ids to i2c-id.h in preparation of the I2C
      direct probing method.
      
      This is kept separate so that it can be integrated to
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      f7f3682f
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: I2C cleanup · 6fc7f10c
      Alessandro Zummo authored
      This patch, completely optional, removes from drivers/i2c/chips all the
      drivers that are implemented in the new RTC subsystem.
      
      It should be noted that none of the current driver is actually integrated,
      i.e.  usable without further patches.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      6fc7f10c
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: class · 0c86edc0
      Alessandro Zummo authored
      Add the basic RTC subsystem infrastructure to the kernel.
      
      rtc/class.c - registration facilities for RTC drivers
      rtc/interface.c - kernel/rtc interface functions
      rtc/hctosys.c - snippet of code that copies hw clock to sw clock
      		at bootup, if configured to do so.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      0c86edc0
    • Richard Purdie's avatar
      [PATCH] RTC subsystem: ARM Integrator cleanup · 4079c39a
      Richard Purdie authored
      Fix some namespace conflicts between the RTC subsystem and the ARM Integrator
      time functions.
      Signed-off-by: default avatarRichard Purdie <rpurdie@rpsys.net>
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      4079c39a
    • Alessandro Zummo's avatar
      [PATCH] RTC subsystem: ARM cleanup · 12b824fb
      Alessandro Zummo authored
      This patch removes from the ARM subsytem some of the rtc-related functions
      that have been included in the RTC subsystem.  It also fixes some naming
      collisions.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      12b824fb
    • Alessandro Zummo's avatar
      [PATCH] RTC Subsystem: library functions · c58411e9
      Alessandro Zummo authored
      RTC and date/time related functions.
      Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      c58411e9
    • Yoichi Yuasa's avatar
      [PATCH] mips: fixed collision of rtc function name · d23ee8fe
      Yoichi Yuasa authored
      Fix the collision of rtc function name.
      Signed-off-by: default avatarYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
      Cc: Alessandro Zummo <a.zummo@towertech.it>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      d23ee8fe
    • Alan Stern's avatar
      [PATCH] Notifier chain update: API changes · e041c683
      Alan Stern authored
      The kernel's implementation of notifier chains is unsafe.  There is no
      protection against entries being added to or removed from a chain while the
      chain is in use.  The issues were discussed in this thread:
      
          http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2
      
      We noticed that notifier chains in the kernel fall into two basic usage
      classes:
      
      	"Blocking" chains are always called from a process context
      	and the callout routines are allowed to sleep;
      
      	"Atomic" chains can be called from an atomic context and
      	the callout routines are not allowed to sleep.
      
      We decided to codify this distinction and make it part of the API.  Therefore
      this set of patches introduces three new, parallel APIs: one for blocking
      notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
      really just the old API under a new name).  New kinds of data structures are
      used for the heads of the chains, and new routines are defined for
      registration, unregistration, and calling a chain.  The three APIs are
      explained in include/linux/notifier.h and their implementation is in
      kernel/sys.c.
      
      With atomic and blocking chains, the implementation guarantees that the chain
      links will not be corrupted and that chain callers will not get messed up by
      entries being added or removed.  For raw chains the implementation provides no
      guarantees at all; users of this API must provide their own protections.  (The
      idea was that situations may come up where the assumptions of the atomic and
      blocking APIs are not appropriate, so it should be possible for users to
      handle these things in their own way.)
      
      There are some limitations, which should not be too hard to live with.  For
      atomic/blocking chains, registration and unregistration must always be done in
      a process context since the chain is protected by a mutex/rwsem.  Also, a
      callout routine for a non-raw chain must not try to register or unregister
      entries on its own chain.  (This did happen in a couple of places and the code
      had to be changed to avoid it.)
      
      Since atomic chains may be called from within an NMI handler, they cannot use
      spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
      entirely in the unregister routine, which is okay since unregistration is much
      less frequent that calling a chain.
      
      Here is the list of chains that we adjusted and their classifications.  None
      of them use the raw API, so for the moment it is only a placeholder.
      
        ATOMIC CHAINS
        -------------
      arch/i386/kernel/traps.c:		i386die_chain
      arch/ia64/kernel/traps.c:		ia64die_chain
      arch/powerpc/kernel/traps.c:		powerpc_die_chain
      arch/sparc64/kernel/traps.c:		sparc64die_chain
      arch/x86_64/kernel/traps.c:		die_chain
      drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
      kernel/panic.c:				panic_notifier_list
      kernel/profile.c:			task_free_notifier
      net/bluetooth/hci_core.c:		hci_notifier
      net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
      net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
      net/ipv6/addrconf.c:			inet6addr_chain
      net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
      net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
      net/netlink/af_netlink.c:		netlink_chain
      
        BLOCKING CHAINS
        ---------------
      arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
      arch/s390/kernel/process.c:		idle_chain
      arch/x86_64/kernel/process.c		idle_notifier
      drivers/base/memory.c:			memory_chain
      drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
      drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
      drivers/macintosh/adb.c:		adb_client_list
      drivers/macintosh/via-pmu.c		sleep_notifier_list
      drivers/macintosh/via-pmu68k.c		sleep_notifier_list
      drivers/macintosh/windfarm_core.c	wf_client_list
      drivers/usb/core/notify.c		usb_notifier_list
      drivers/video/fbmem.c			fb_notifier_list
      kernel/cpu.c				cpu_chain
      kernel/module.c				module_notify_list
      kernel/profile.c			munmap_notifier
      kernel/profile.c			task_exit_notifier
      kernel/sys.c				reboot_notifier_list
      net/core/dev.c				netdev_chain
      net/decnet/dn_dev.c:			dnaddr_chain
      net/ipv4/devinet.c:			inetaddr_chain
      
      It's possible that some of these classifications are wrong.  If they are,
      please let us know or submit a patch to fix them.  Note that any chain that
      gets called very frequently should be atomic, because the rwsem read-locking
      used for blocking chains is very likely to incur cache misses on SMP systems.
      (However, if the chain's callout routines may sleep then the chain cannot be
      atomic.)
      
      The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
      material written by Keith Owens and suggestions from Paul McKenney and Andrew
      Morton.
      
      [jes@sgi.com: restructure the notifier chain initialization macros]
      Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
      Signed-off-by: default avatarChandra Seetharaman <sekharan@us.ibm.com>
      Signed-off-by: default avatarJes Sorensen <jes@sgi.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      e041c683
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes updates 2 · 76b81e2b
      Ingo Molnar authored
      futex.h updates:
      
      - get rid of FUTEX_OWNER_PENDING - it's not used
      - reduce ROBUST_LIST_LIMIT to a saner value
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      76b81e2b
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes updates · 8f17d3a5
      Ingo Molnar authored
      - fix: initialize the robust list(s) to NULL in copy_process.
      
      - doc update
      
      - cleanup: rename _inuser to _inatomic
      
      - __user cleanups and other small cleanups
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Arjan van de Ven <arjan@infradead.org>
      Cc: Ulrich Drepper <drepper@redhat.com>
      Cc: Andi Kleen <ak@muc.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8f17d3a5
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: x86_64 · 8fdd6c6d
      Ingo Molnar authored
      x86_64: add the futex_atomic_cmpxchg_inuser() assembly implementation, and
      wire up the new syscalls.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
      Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
      Cc: Andi Kleen <ak@muc.de>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      8fdd6c6d
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: i386 · dfd4e3ec
      Ingo Molnar authored
      i386: add the futex_atomic_cmpxchg_inuser() assembly implementation, and wire
      up the new syscalls.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
      Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      dfd4e3ec
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: compat · 34f192c6
      Ingo Molnar authored
      32-bit syscall compatibility support.  (This patch also moves all futex
      related compat functionality into kernel/futex_compat.c.)
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
      Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      34f192c6
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: docs · 2eec9ad9
      Ingo Molnar authored
      Add robust-futex documentation.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      2eec9ad9
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: core · 0771dfef
      Ingo Molnar authored
      Add the core infrastructure for robust futexes: structure definitions, the new
      syscalls and the do_exit() based cleanup mechanism.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
      Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
      Cc: Michael Kerrisk <mtk-manpages@gmx.net>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      0771dfef
    • Ingo Molnar's avatar
      [PATCH] lightweight robust futexes: arch defaults · e9056f13
      Ingo Molnar authored
      This patchset provides a new (written from scratch) implementation of robust
      futexes, called "lightweight robust futexes".  We believe this new
      implementation is faster and simpler than the vma-based robust futex solutions
      presented before, and we'd like this patchset to be adopted in the upstream
      kernel.  This is version 1 of the patchset.
      
        Background
        ----------
      
      What are robust futexes?  To answer that, we first need to understand what
      futexes are: normal futexes are special types of locks that in the
      noncontended case can be acquired/released from userspace without having to
      enter the kernel.
      
      A futex is in essence a user-space address, e.g.  a 32-bit lock variable
      field.  If userspace notices contention (the lock is already owned and someone
      else wants to grab it too) then the lock is marked with a value that says
      "there's a waiter pending", and the sys_futex(FUTEX_WAIT) syscall is used to
      wait for the other guy to release it.  The kernel creates a 'futex queue'
      internally, so that it can later on match up the waiter with the waker -
      without them having to know about each other.  When the owner thread releases
      the futex, it notices (via the variable value) that there were waiter(s)
      pending, and does the sys_futex(FUTEX_WAKE) syscall to wake them up.  Once all
      waiters have taken and released the lock, the futex is again back to
      'uncontended' state, and there's no in-kernel state associated with it.  The
      kernel completely forgets that there ever was a futex at that address.  This
      method makes futexes very lightweight and scalable.
      
      "Robustness" is about dealing with crashes while holding a lock: if a process
      exits prematurely while holding a pthread_mutex_t lock that is also shared
      with some other process (e.g.  yum segfaults while holding a pthread_mutex_t,
      or yum is kill -9-ed), then waiters for that lock need to be notified that the
      last owner of the lock exited in some irregular way.
      
      To solve such types of problems, "robust mutex" userspace APIs were created:
      pthread_mutex_lock() returns an error value if the owner exits prematurely -
      and the new owner can decide whether the data protected by the lock can be
      recovered safely.
      
      There is a big conceptual problem with futex based mutexes though: it is the
      kernel that destroys the owner task (e.g.  due to a SEGFAULT), but the kernel
      cannot help with the cleanup: if there is no 'futex queue' (and in most cases
      there is none, futexes being fast lightweight locks) then the kernel has no
      information to clean up after the held lock!  Userspace has no chance to clean
      up after the lock either - userspace is the one that crashes, so it has no
      opportunity to clean up.  Catch-22.
      
      In practice, when e.g.  yum is kill -9-ed (or segfaults), a system reboot is
      needed to release that futex based lock.  This is one of the leading
      bugreports against yum.
      
      To solve this problem, 'Robust Futex' patches were created and presented on
      lkml: the one written by Todd Kneisel and David Singleton is the most advanced
      at the moment.  These patches all tried to extend the futex abstraction by
      registering futex-based locks in the kernel - and thus give the kernel a
      chance to clean up.
      
      E.g.  in David Singleton's robust-futex-6.patch, there are 3 new syscall
      variants to sys_futex(): FUTEX_REGISTER, FUTEX_DEREGISTER and FUTEX_RECOVER.
      The kernel attaches such robust futexes to vmas (via
      vma->vm_file->f_mapping->robust_head), and at do_exit() time, all vmas are
      searched to see whether they have a robust_head set.
      
      Lots of work went into the vma-based robust-futex patch, and recently it has
      improved significantly, but unfortunately it still has two fundamental
      problems left:
      
       - they have quite complex locking and race scenarios.  The vma-based
         patches had been pending for years, but they are still not completely
         reliable.
      
       - they have to scan _every_ vma at sys_exit() time, per thread!
      
      The second disadvantage is a real killer: pthread_exit() takes around 1
      microsecond on Linux, but with thousands (or tens of thousands) of vmas every
      pthread_exit() takes a millisecond or more, also totally destroying the CPU's
      L1 and L2 caches!
      
      This is very much noticeable even for normal process sys_exit_group() calls:
      the kernel has to do the vma scanning unconditionally!  (this is because the
      kernel has no knowledge about how many robust futexes there are to be cleaned
      up, because a robust futex might have been registered in another task, and the
      futex variable might have been simply mmap()-ed into this process's address
      space).
      
      This huge overhead forced the creation of CONFIG_FUTEX_ROBUST, but worse than
      that: the overhead makes robust futexes impractical for any type of generic
      Linux distribution.
      
      So it became clear to us, something had to be done.  Last week, when Thomas
      Gleixner tried to fix up the vma-based robust futex patch in the -rt tree, he
      found a handful of new races and we were talking about it and were analyzing
      the situation.  At that point a fundamentally different solution occured to
      me.  This patchset (written in the past couple of days) implements that new
      solution.  Be warned though - the patchset does things we normally dont do in
      Linux, so some might find the approach disturbing.  Parental advice
      recommended ;-)
      
        New approach to robust futexes
        ------------------------------
      
      At the heart of this new approach there is a per-thread private list of robust
      locks that userspace is holding (maintained by glibc) - which userspace list
      is registered with the kernel via a new syscall [this registration happens at
      most once per thread lifetime].  At do_exit() time, the kernel checks this
      user-space list: are there any robust futex locks to be cleaned up?
      
      In the common case, at do_exit() time, there is no list registered, so the
      cost of robust futexes is just a simple current->robust_list != NULL
      comparison.  If the thread has registered a list, then normally the list is
      empty.  If the thread/process crashed or terminated in some incorrect way then
      the list might be non-empty: in this case the kernel carefully walks the list
      [not trusting it], and marks all locks that are owned by this thread with the
      FUTEX_OWNER_DEAD bit, and wakes up one waiter (if any).
      
      The list is guaranteed to be private and per-thread, so it's lockless.  There
      is one race possible though: since adding to and removing from the list is
      done after the futex is acquired by glibc, there is a few instructions window
      for the thread (or process) to die there, leaving the futex hung.  To protect
      against this possibility, userspace (glibc) also maintains a simple per-thread
      'list_op_pending' field, to allow the kernel to clean up if the thread dies
      after acquiring the lock, but just before it could have added itself to the
      list.  Glibc sets this list_op_pending field before it tries to acquire the
      futex, and clears it after the list-add (or list-remove) has finished.
      
      That's all that is needed - all the rest of robust-futex cleanup is done in
      userspace [just like with the previous patches].
      
      Ulrich Drepper has implemented the necessary glibc support for this new
      mechanism, which fully enables robust mutexes.  (Ulrich plans to commit these
      changes to glibc-HEAD later today.)
      
      Key differences of this userspace-list based approach, compared to the vma
      based method:
      
       - it's much, much faster: at thread exit time, there's no need to loop
         over every vma (!), which the VM-based method has to do.  Only a very
         simple 'is the list empty' op is done.
      
       - no VM changes are needed - 'struct address_space' is left alone.
      
       - no registration of individual locks is needed: robust mutexes dont need
         any extra per-lock syscalls.  Robust mutexes thus become a very lightweight
         primitive - so they dont force the application designer to do a hard choice
         between performance and robustness - robust mutexes are just as fast.
      
       - no per-lock kernel allocation happens.
      
       - no resource limits are needed.
      
       - no kernel-space recovery call (FUTEX_RECOVER) is needed.
      
       - the implementation and the locking is "obvious", and there are no
         interactions with the VM.
      
        Performance
        -----------
      
      I have benchmarked the time needed for the kernel to process a list of 1
      million (!) held locks, using the new method [on a 2GHz CPU]:
      
       - with FUTEX_WAIT set [contended mutex]: 130 msecs
       - without FUTEX_WAIT set [uncontended mutex]: 30 msecs
      
      I have also measured an approach where glibc does the lock notification [which
      it currently does for !pshared robust mutexes], and that took 256 msecs -
      clearly slower, due to the 1 million FUTEX_WAKE syscalls userspace had to do.
      
      (1 million held locks are unheard of - we expect at most a handful of locks to
      be held at a time.  Nevertheless it's nice to know that this approach scales
      nicely.)
      
        Implementation details
        ----------------------
      
      The patch adds two new syscalls: one to register the userspace list, and one
      to query the registered list pointer:
      
       asmlinkage long
       sys_set_robust_list(struct robust_list_head __user *head,
                           size_t len);
      
       asmlinkage long
       sys_get_robust_list(int pid, struct robust_list_head __user **head_ptr,
                           size_t __user *len_ptr);
      
      List registration is very fast: the pointer is simply stored in
      current->robust_list.  [Note that in the future, if robust futexes become
      widespread, we could extend sys_clone() to register a robust-list head for new
      threads, without the need of another syscall.]
      
      So there is virtually zero overhead for tasks not using robust futexes, and
      even for robust futex users, there is only one extra syscall per thread
      lifetime, and the cleanup operation, if it happens, is fast and
      straightforward.  The kernel doesnt have any internal distinction between
      robust and normal futexes.
      
      If a futex is found to be held at exit time, the kernel sets the highest bit
      of the futex word:
      
      	#define FUTEX_OWNER_DIED        0x40000000
      
      and wakes up the next futex waiter (if any). User-space does the rest of
      the cleanup.
      
      Otherwise, robust futexes are acquired by glibc by putting the TID into the
      futex field atomically.  Waiters set the FUTEX_WAITERS bit:
      
      	#define FUTEX_WAITERS           0x80000000
      
      and the remaining bits are for the TID.
      
        Testing, architecture support
        -----------------------------
      
      I've tested the new syscalls on x86 and x86_64, and have made sure the parsing
      of the userspace list is robust [ ;-) ] even if the list is deliberately
      corrupted.
      
      i386 and x86_64 syscalls are wired up at the moment, and Ulrich has tested the
      new glibc code (on x86_64 and i386), and it works for his robust-mutex
      testcases.
      
      All other architectures should build just fine too - but they wont have the
      new syscalls yet.
      
      Architectures need to implement the new futex_atomic_cmpxchg_inuser() inline
      function before writing up the syscalls (that function returns -ENOSYS right
      now).
      
      This patch:
      
      Add placeholder futex_atomic_cmpxchg_inuser() implementations to every
      architecture that supports futexes.  It returns -ENOSYS.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarArjan van de Ven <arjan@infradead.org>
      Acked-by: default avatarUlrich Drepper <drepper@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      e9056f13
    • Ingo Molnar's avatar
      [PATCH] mips: add ptr_to_compat() · 62ac285f
      Ingo Molnar authored
      Add ptr_to_compat() - needed by the new robust futex code.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: Ralf Baechle <ralf@linux-mips.org>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      62ac285f
    • Ingo Molnar's avatar
      [PATCH] parisc: add ptr_to_compat() · 213b63b7
      Ingo Molnar authored
      Add ptr_to_compat() to parisc - needed by the new robust futex code.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: Kyle McMartin <kyle@mcmartin.ca>
      Cc: Grant Grundler <iod00d@hp.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      213b63b7
    • Ingo Molnar's avatar
      [PATCH] s390: add ptr_to_compat() · f267fa9f
      Ingo Molnar authored
      Add ptr_to_compat() to s390 - needed by the new robust-futex code.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      
      untested. CHECKME: am i right about the 0x7fffffffUL masking?
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      f267fa9f
    • Ingo Molnar's avatar
      [PATCH] ia64: add ptr_to_compat() · 66e863ac
      Ingo Molnar authored
      Add ptr_to_compat() to ia64 - needed by the robust-futex code.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      66e863ac
    • Dave Hansen's avatar
      [PATCH] unify PFN_* macros · 22a9835c
      Dave Hansen authored
      Just about every architecture defines some macros to do operations on pfns.
       They're all virtually identical.  This patch consolidates all of them.
      
      One minor glitch is that at least i386 uses them in a very skeletal header
      file.  To keep away from #include dependency hell, I stuck the new
      definitions in a new, isolated header.
      
      Of all of the implementations, sh64 is the only one that varied by a bit.
      It used some masks to ensure that any sign-extension got ripped away before
      the arithmetic is done.  This has been posted to that sh64 maintainers and
      the development list.
      
      Compiles on x86, x86_64, ia64 and ppc64.
      Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
      22a9835c