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linux-next/include/asm-ia64
Alan Stern e041c68341 [PATCH] Notifier chain update: API changes
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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 08:44:50 -08:00
..
sn [PATCH] EFI: keep physical table addresses in efi structure 2006-03-26 08:56:54 -08:00
a.out.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
acpi-ext.h [ACPI] fix IA64 build warning 2005-08-04 22:29:34 -04:00
acpi.h [IA64] Increase max node count on SN platforms 2006-03-24 13:14:21 -08:00
agp.h [PATCH] AGP fix for Xen VMM 2005-06-07 12:35:43 -07:00
asmmacro.h [IA64] MCA recovery: kernel context recovery table 2006-03-24 09:49:52 -08:00
atomic.h [PATCH] atomic: add_unless cmpxchg optimise 2006-03-23 07:38:17 -08:00
auxvec.h [PATCH] auxiliary vector cleanups 2005-09-07 16:57:21 -07:00
bitops.h [PATCH] bitops: ia64: use generic bitops 2006-03-26 08:57:12 -08:00
break.h [PATCH] Kprobes/IA64: kdebug die notification mechanism 2005-06-23 09:45:22 -07:00
bug.h [PATCH] remove gcc-2 checks 2006-01-08 20:14:02 -08:00
bugs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
byteorder.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cache.h [PATCH] Move read_mostly definition to asm/cache.h 2006-03-23 07:38:10 -08:00
cacheflush.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
checksum.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
compat.h [PATCH] ia64: add ptr_to_compat() 2006-03-27 08:44:48 -08:00
cpu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cputime.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
current.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
cyclone.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
delay.h [IA64] disable preemption in udelay() 2005-12-16 10:00:24 -08:00
div64.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dma-mapping.h [PATCH] ia64: re-implement dma_get_cache_alignment to avoid EXPORT_SYMBOL 2005-11-07 07:53:23 -08:00
dma.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
dmi.h [PATCH] ia64: use i386 dmi_scan.c 2006-03-26 08:56:54 -08:00
elf.h [PATCH] auxiliary vector cleanups 2005-09-07 16:57:21 -07:00
emergency-restart.h [PATCH] Add emergency_restart() 2005-07-26 14:35:41 -07:00
errno.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fcntl.h [PATCH] Clean up struct flock definitions 2005-09-07 16:57:38 -07:00
fpswa.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
fpu.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
futex.h [PATCH] consolidate asm/futex.h 2006-01-08 20:13:39 -08:00
gcc_intrin.h [IA64] fix fls() 2005-04-21 11:07:59 -07:00
hardirq.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
hw_irq.h [PATCH] x86/x86_64: deferred handling of writes to /proc/irqxx/smp_affinity 2005-09-07 16:57:15 -07:00
ia32.h [IA64] Change SET_PERSONALITY to comply with comment in binfmt_elf.c. 2005-12-06 09:12:34 -08:00
ia64regs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ide.h [PATCH] ia64: drop arch-specific IDE MAX_HWIFS definition 2006-02-03 08:32:11 -08:00
intel_intrin.h [IA64] use icc defined constant 2006-02-07 08:49:27 -08:00
intrinsics.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
io.h [PATCH] ia64: ioremap: check EFI for valid memory attributes 2006-03-26 08:56:54 -08:00
ioctl.h [PATCH] Generic ioctl.h 2006-01-10 08:01:34 -08:00
ioctls.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
iosapic.h [IA64] Minor cleanups - remove unnecessary function prototype in iosapic.h 2005-09-07 14:00:40 -07:00
ipcbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
irq.h [IA64] Manual merge fix for 3 files 2005-09-08 14:27:13 -07:00
kdebug.h [PATCH] Notifier chain update: API changes 2006-03-27 08:44:50 -08:00
kmap_types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
kprobes.h [IA64] prevent accidental modification of args in jprobe handler 2006-01-13 14:45:21 -08:00
kregs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
linkage.h [PATCH] abstract type/size specification for assembly 2006-03-24 07:33:25 -08:00
local.h [IA64] Fix missing parameter for local_add/sub 2005-12-07 11:30:11 -08:00
machvec_dig.h [IA64] cleanup dig_irq_init 2006-03-24 13:12:46 -08:00
machvec_hpsim.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
machvec_hpzx1_swiotlb.h [IA64] more robust zx1/sx1000 machvec support 2005-09-14 16:22:11 -07:00
machvec_hpzx1.h [IA64] more robust zx1/sx1000 machvec support 2005-09-14 16:22:11 -07:00
machvec_init.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
machvec_sn2.h Pull sn2-mmio-writes into release branch 2006-03-21 08:21:26 -08:00
machvec.h [IA64] hooks to wait for mmio writes to drain when migrating processes 2006-01-26 15:55:52 -08:00
mc146818rtc.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mca_asm.h [PATCH] MCA/INIT: use per cpu stacks 2005-09-11 14:08:41 -07:00
mca.h [IA64] support for cpu0 removal 2006-01-05 10:24:20 -08:00
meminit.h Pull sparsemem-v5 into release branch 2005-10-28 14:32:56 -07:00
mman.h [PATCH] add asm-generic/mman.h 2006-02-15 15:32:22 -08:00
mmu_context.h [IA64] make mmu_context.h and tlb.c 80-column friendly 2005-11-03 14:43:50 -08:00
mmu.h [IA64] Fix race in mm-context wrap-around logic. 2005-08-12 15:05:21 -07:00
mmzone.h [PATCH] V5 ia64 SPARSEMEM - conditional changes for SPARSEMEM 2005-10-04 13:21:13 -07:00
module.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
msgbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
msi.h [PATCH] PCI: Change MSI to use physical delivery mode always 2005-11-10 16:09:18 -08:00
mutex.h [IA64] implement ia64 specific mutex primitives 2006-01-26 13:10:19 -08:00
namei.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
nodedata.h [PATCH] V5 ia64 SPARSEMEM - conditional changes for SPARSEMEM 2005-10-04 13:21:13 -07:00
numa.h [IA64] Increase max node count on SN platforms 2006-03-24 13:14:41 -08:00
numnodes.h [IA64] Increase max node count on SN platforms 2006-03-24 13:14:03 -08:00
page.h [PATCH] unify pfn_to_page: ia64 pfn_to_page 2006-03-27 08:44:47 -08:00
pal.h [IA64] New IA64 core/thread detection patch 2006-03-24 13:15:23 -08:00
param.h [PATCH] ia64: Selectable Timer Interrupt Frequency 2005-06-23 09:45:10 -07:00
parport.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
patch.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
pci.h [PATCH] Make sparc64 use setup-res.c 2005-09-08 14:57:25 -07:00
percpu.h [PATCH] adjust per_cpu definition in non-SMP case 2005-06-23 09:45:28 -07:00
perfmon_default_smpl.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
perfmon.h [IA64] alternate perfmon handler 2005-05-18 16:14:30 -07:00
pgalloc.h [IA64] 4-level page tables 2005-11-11 09:37:29 -08:00
pgtable.h [PATCH] hugepage: Move hugetlb_free_pgd_range() prototype to hugetlb.h 2006-03-22 07:54:04 -08:00
poll.h [PATCH] POLLRDHUP/EPOLLRDHUP handling for half-closed devices notifications 2006-03-25 08:22:56 -08:00
posix_types.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
processor.h [IA64] add init declaration to cpu initialization functions 2006-03-22 16:04:37 -08:00
ptrace_offsets.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ptrace.h [PATCH] ia64: task_pt_regs() 2006-01-12 09:08:58 -08:00
resource.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rse.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
rwsem.h [PATCH] add sem_is_read/write_locked() 2005-10-29 21:40:35 -07:00
sal.h [IA64] avoid broken SAL_CACHE_FLUSH implementations 2006-02-02 13:25:54 -08:00
scatterlist.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sections.h [PATCH] kprobes/ia64: refuse kprobe on ivt code 2005-06-27 15:23:54 -07:00
segment.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
semaphore.h [IA64] Fix bug in ia64 specific down() function 2006-01-17 14:04:00 -08:00
sembuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
serial.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
setup.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
shmbuf.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
shmparam.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sigcontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
siginfo.h [PATCH] consolidate SIGEV_PAD_SIZE 2005-05-01 08:59:08 -07:00
signal.h [IA64] Delete MCA/INIT sigdelayed code 2006-01-26 13:23:27 -08:00
smp.h [PATCH] smp_processor_id() cleanup 2005-06-21 18:46:13 -07:00
socket.h [NET]: Introduce SO_{SND,RCV}BUFFORCE socket options 2005-08-29 15:31:35 -07:00
sockios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sparsemem.h [PATCH] V5 ia64 SPARSEMEM - conditional changes for SPARSEMEM 2005-10-04 13:21:13 -07:00
spinlock_types.h [PATCH] spinlock consolidation 2005-09-10 10:06:21 -07:00
spinlock.h [PATCH] remove gcc-2 checks 2006-01-08 20:14:02 -08:00
stat.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
statfs.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
string.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
suspend.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
system.h [PATCH] kill include/linux/platform.h, default_idle() cleanup 2006-03-24 07:33:21 -08:00
termbits.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
termios.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
thread_info.h Pull sn2-mmio-writes into release branch 2006-03-21 08:21:26 -08:00
timex.h [IA64] ia64: simplify and fix udelay() 2006-02-15 13:37:04 -08:00
tlb.h [PATCH] mm: tlb_finish_mmu forget rss 2005-10-29 21:40:37 -07:00
tlbflush.h [IA64] Use bitmaps for efficient context allocation/free 2005-10-31 14:36:05 -08:00
topology.h [PATCH] Export cpu topology in sysfs 2006-02-03 08:32:09 -08:00
types.h [PATCH] sab: consolidate kmem_bufctl_t 2005-09-05 00:05:48 -07:00
uaccess.h [PATCH] ia64 basic __user annotations 2005-09-29 08:46:27 -07:00
ucontext.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
unaligned.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
uncached.h [PATCH] ia64 uncached alloc 2005-06-21 18:46:18 -07:00
unistd.h [IA64] unshare system call registration for ia64 2006-02-08 15:43:38 -08:00
unwind.h [IA64] MCA/INIT: remove obsolete unwind code 2005-09-11 14:09:34 -07:00
user.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
ustack.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
vga.h [IA64-SGI] pcdp: add PCDP pci interface support 2005-06-28 09:09:06 -07:00
xor.h Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00