Peter Staubach c293621bbf [PATCH] stale POSIX lock handling ... I believe that there is a problem with the handling of POSIX locks, which the attached patch should address. The problem appears to be a race between fcntl(2) and close(2). A multithreaded application could close a file descriptor at the same time as it is trying to acquire a lock using the same file descriptor. I would suggest that that multithreaded application is not providing the proper synchronization for itself, but the OS should still behave correctly. SUS3 (Single UNIX Specification Version 3, read: POSIX) indicates that when a file descriptor is closed, that all POSIX locks on the file, owned by the process which closed the file descriptor, should be released. The trick here is when those locks are released. The current code releases all locks which exist when close is processing, but any locks in progress are handled when the last reference to the open file is released. There are three cases to consider. One is the simple case, a multithreaded (mt) process has a file open and races to close it and acquire a lock on it. In this case, the close will release one reference to the open file and when the fcntl is done, it will release the other reference. For this situation, no locks should exist on the file when both the close and fcntl operations are done. The current system will handle this case because the last reference to the open file is being released. The second case is when the mt process has dup(2)'d the file descriptor. The close will release one reference to the file and the fcntl, when done, will release another, but there will still be at least one more reference to the open file. One could argue that the existence of a lock on the file after the close has completed is okay, because it was acquired after the close operation and there is still a way for the application to release the lock on the file, using an existing file descriptor. The third case is when the mt process has forked, after opening the file and either before or after becoming an mt process. In this case, each process would hold a reference to the open file. For each process, this degenerates to first case above. However, the lock continues to exist until both processes have released their references to the open file. This lock could block other lock requests. The changes to release the lock when the last reference to the open file aren't quite right because they would allow the lock to exist as long as there was a reference to the open file. This is too long. The new proposed solution is to add support in the fcntl code path to detect a race with close and then to release the lock which was just acquired when such as race is detected. This causes locks to be released in a timely fashion and for the system to conform to the POSIX semantic specification. This was tested by instrumenting a kernel to detect the handling locks and then running a program which generates case #3 above. A dangling lock could be reliably generated. When the changes to detect the close/fcntl race were added, a dangling lock could no longer be generated. Cc: Matthew Wilcox <willy@debian.org> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>		2005-07-27 16:26:06 -07:00
..
byteorder	[PATCH] swabb.h warning fixes	2005-06-28 21:20:31 -07:00
dvb
hdlc
isdn
lockd
mmc
mtd	[MTD] XIP cleanup	2005-07-07 16:50:16 +02:00
netfilter_arp
netfilter_bridge
netfilter_ipv4	[NETFILTER]: Fix ip_conntrack_put() prototype.	2005-07-26 15:39:28 -07:00
netfilter_ipv6
nfsd	[PATCH] nfsd4: check lock type against openmode.	2005-07-07 18:24:11 -07:00
raid	[PATCH] md/raid1: clear bitmap when fullsync completes	2005-07-15 09:54:51 -07:00
sunrpc
tc_act
tc_ematch	[PKT_SCHED]: em_meta: Kill TCF_META_ID_{INDEV,SECURITY,TCVERDICT}	2005-07-22 14:43:52 -07:00
8250_pci.h
a.out.h	[PATCH] Use ALIGN to remove duplicate code	2005-06-25 16:25:02 -07:00
ac97_codec.h
acct.h
acpi.h	[ACPI] merge acpi-2.6.12 branch into latest Linux 2.6.13-rc...	2005-07-12 17:21:56 -04:00
adb.h
adfs_fs_i.h
adfs_fs_sb.h
adfs_fs.h
affs_fs.h
affs_hardblocks.h
agp_backend.h
agpgart.h
aio_abi.h
aio.h
amifd.h
amifdreg.h
amigaffs.h
apm_bios.h
arcdevice.h
arcfb.h
ata.h
atalk.h	[ATALK]: Include asm/byteorder.h in linux/atalk.h	2005-06-26 15:28:10 -07:00
atm_eni.h
atm_he.h
atm_idt77105.h
atm_nicstar.h
atm_suni.h
atm_tcp.h
atm_zatm.h
atm.h
atmapi.h
atmarp.h
atmbr2684.h
atmclip.h
atmdev.h
atmioc.h
atmlec.h
atmmpc.h
atmppp.h
atmsap.h
atmsvc.h
attribute_container.h
audit.h	[SPARC64]: Add syscall auditing support.	2005-07-10 19:29:45 -07:00
auto_fs4.h
auto_fs.h
awe_voice.h
ax25.h
b1lli.h
b1pcmcia.h
backing-dev.h
backlight.h
baycom.h
bcd.h
bfs_fs.h
binfmts.h
bio.h	[PATCH] Update cfq io scheduler to time sliced design	2005-06-27 14:33:29 -07:00
bitmap.h
bitops.h
blkdev.h	[PATCH] blk: light iocontext ops	2005-06-28 21:20:35 -07:00
blkpg.h
blockgroup_lock.h
bootmem.h	[PATCH] kdump: Retrieve saved max pfn	2005-06-25 16:24:52 -07:00
bpqether.h
buffer_head.h	[PATCH] page_uptodate locking scalability	2005-07-07 18:23:45 -07:00
cache.h	[SPARC64]: Add __read_mostly support.	2005-07-10 15:45:11 -07:00
capability.h
capi.h
cciss_ioctl.h	[PATCH] cciss: pci domain info pass 2	2005-06-27 15:11:48 -07:00
cd1400.h
cdev.h
cdk.h
cdrom.h
chio.h
circ_buf.h
cobalt-nvram.h
coda_cache.h
coda_fs_i.h
coda_linux.h
coda_proc.h
coda_psdev.h
coda.h
coff.h
com20020.h
compat_ioctl.h	[SPARC64/COMPAT]: Add some compat ioctl for ppdev	2005-07-04 13:23:45 -07:00
compat.h
compiler-gcc2.h
compiler-gcc3.h
compiler-gcc4.h
compiler-gcc.h
compiler-intel.h
compiler.h
completion.h
comstats.h
concap.h
config.h
console_struct.h
console.h
consolemap.h
cpu.h	[PATCH] make smp_prepare_cpu to a weak function	2005-06-25 16:24:30 -07:00
cpufreq.h	[PATCH] pm: fix u32 vs. pm_message_t confusion in cpufreq	2005-07-07 18:23:43 -07:00
cpumask.h
cpuset.h
cramfs_fs_sb.h
cramfs_fs.h
crash_dump.h	[PATCH] kdump: Access dump file in elf format (/proc/vmcore)	2005-06-25 16:24:53 -07:00
crc32.h
crc32c.h
crc-ccitt.h
crypto.h	[CRYPTO] Ensure cit_iv is aligned correctly	2005-07-06 13:53:29 -07:00
cryptohash.h
ctype.h
cuda.h
cyclades.h
cyclomx.h
cycx_cfm.h
cycx_drv.h
cycx_x25.h
dcache.h
dcookies.h
debugfs.h
delay.h
devfs_fs_kernel.h
devfs_fs.h
device-mapper.h
device.h	[ACPI] merge acpi-2.6.12 branch into latest Linux 2.6.13-rc...	2005-07-12 17:21:56 -04:00
devpts_fs.h
dio.h
dirent.h
divert.h
dm9000.h
dm-ioctl.h
dma-mapping.h
dmapool.h
dmi.h	[PATCH] I8K: use standard DMI interface	2005-06-25 16:24:24 -07:00
dn.h
dnotify.h
dqblk_v1.h
dqblk_v2.h
dqblk_xfs.h
ds1286.h
dtlk.h
edd.h
eeprom.h
efi.h
efs_dir.h
efs_fs_i.h
efs_fs_sb.h
efs_fs.h
efs_vh.h
eisa.h
elevator.h	[PATCH] Update cfq io scheduler to time sliced design	2005-06-27 14:33:29 -07:00
elf-fdpic.h
elf.h
elfcore.h
err.h
errno.h
errqueue.h
etherdevice.h	[NET]: __be'ify *_type_trans()	2005-07-12 12:08:43 -07:00
ethtool.h
eventpoll.h
ext2_fs_sb.h
ext2_fs.h	[PATCH] xip: ext2: execute in place	2005-06-24 00:06:41 -07:00
ext3_fs_i.h
ext3_fs_sb.h
ext3_fs.h	[PATCH] ext3: fix options parsing	2005-07-12 16:01:01 -07:00
ext3_jbd.h
fadvise.h	[PATCH] s390: fadvise hint values.	2005-07-13 11:25:24 -07:00
fb.h
fcdevice.h
fcntl.h
fd1772.h
fd.h
fddidevice.h	[NET]: __be'ify *_type_trans()	2005-07-12 12:08:43 -07:00
fdreg.h
file.h
filter.h
firmware.h
flat.h
font.h
fs_struct.h
fs.h	[PATCH] stale POSIX lock handling	2005-07-27 16:26:06 -07:00
fsl_devices.h
fsnotify.h	[PATCH] inotify: event ordering	2005-07-13 11:09:31 -07:00
ftape-header-segment.h
ftape-vendors.h
ftape.h
futex.h
gameport.h
gen_stats.h
genalloc.h
generic_serial.h
genhd.h
gfp.h	[PATCH] propagate __nocast annotations	2005-07-07 18:23:46 -07:00
hardirq.h	[PATCH] hardirq uses preempt	2005-07-12 16:01:03 -07:00
harrier_defs.h
hash.h
hayesesp.h
hdlc.h	[NET]: __be'ify *_type_trans()	2005-07-12 12:08:43 -07:00
hdlcdrv.h
hdpu_features.h
hdreg.h
hdsmart.h
hiddev.h
highmem.h	[PATCH] kdump: Routines for copying dump pages	2005-06-25 16:24:53 -07:00
highuid.h
hippidevice.h
hpet.h
hpfs_fs.h
hugetlb.h
hwmon-sysfs.h
hysdn_if.h
i2c-algo-bit.h
i2c-algo-ite.h
i2c-algo-pca.h
i2c-algo-pcf.h
i2c-algo-sgi.h
i2c-algo-sibyte.h
i2c-dev.h	[PATCH] headers: include linux/compiler.h for __user	2005-06-28 21:20:32 -07:00
i2c-id.h
i2c-sensor.h
i2c-vid.h
i2c.h
i2o-dev.h	[PATCH] I2O: second code cleanup of sparse warnings and unneeded syncronization	2005-06-24 00:05:29 -07:00
i2o.h	[PATCH] I2O: Lindent run and replacement of printk through osm printing functions	2005-06-24 00:05:29 -07:00
i8k.h
ibmtr.h
icmp.h
icmpv6.h
ide.h
idr.h
if_arcnet.h
if_arp.h
if_bonding.h	bonding: xor/802.3ad improved slave hash	2005-06-26 17:54:11 -04:00
if_bridge.h
if_cablemodem.h
if_ec.h
if_eql.h
if_ether.h
if_fc.h
if_fddi.h
if_frad.h
if_hippi.h
if_infiniband.h
if_ltalk.h
if_packet.h
if_plip.h
if_ppp.h
if_pppox.h
if_shaper.h	[SHAPER]: Switch to spinlocks.	2005-07-05 15:03:46 -07:00
if_slip.h
if_strip.h
if_tr.h
if_tun.h
if_tunnel.h
if_vlan.h
if_wanpipe_common.h
if_wanpipe.h
if.h
igmp.h	[IPV4]: multicast API "join" issues	2005-07-08 17:38:07 -07:00
in6.h	[IPV6]: remove more unused IPV6_AUTHHDR things.	2005-06-28 15:46:24 -07:00
in_route.h
in.h
inet.h
inetdevice.h
init_task.h	[PATCH] Update cfq io scheduler to time sliced design	2005-06-27 14:33:29 -07:00
init.h	[PATCH] x86_64: Change init sections for CPU hotplug support	2005-06-25 16:24:30 -07:00
initrd.h
inotify.h	[PATCH] inotify	2005-07-12 20:38:38 -07:00
input.h	Merge rsync://rsync.kernel.org/pub/scm/linux/kernel/git/dtor/input.git manually	2005-06-27 14:47:31 -07:00
interrupt.h
ioc4.h
ioctl32.h
ioctl.h
ioport.h
ioprio.h	[PATCH] move ioprio syscalls into syscalls.h	2005-07-07 18:23:37 -07:00
ip6_tunnel.h
ip_mp_alg.h
ip.h
ipc.h
ipmi_msgdefs.h
ipmi_smi.h
ipmi.h
ipsec.h
ipv6_route.h
ipv6.h
ipx.h
irda.h
irq_cpustat.h
irq.h	[PATCH] irqpoll	2005-06-28 21:20:35 -07:00
isapnp.h
isdn_divertif.h
isdn_ppp.h
isdn.h
isdnif.h
isicom.h
iso_fs.h
istallion.h
ite_gpio.h
ixjuser.h
jbd.h
jffs2_fs_i.h
jffs2_fs_sb.h
jffs2.h
jffs.h
jhash.h
jiffies.h
journal-head.h
joystick.h
kallsyms.h
kbd_diacr.h
kbd_kern.h
kd.h
kdev_t.h
kernel_stat.h
kernel.h	[PATCH] sched: voluntary kernel preemption	2005-06-25 16:24:45 -07:00
kernelcapi.h
kexec.h	[PATCH] kexec code cleanup	2005-06-25 16:24:55 -07:00
key-ui.h
key.h
keyboard.h
keyctl.h
kfifo.h
klist.h
kmalloc_sizes.h
kmod.h
kobj_map.h
kobject_uevent.h
kobject.h
kprobes.h	[PATCH] kprobes: fix namespace problem and sparc64 build	2005-07-05 19:19:00 -07:00
kref.h
kthread.h
lapb.h
lcd.h
libata.h
libps2.h
limits.h
linkage.h
linux_logo.h
list.h	[PATCH] RCU: clean up a few remaining synchronize_kernel() calls	2005-06-25 16:24:38 -07:00
llc.h
loop.h
lp.h
major.h
matroxfb.h
mbcache.h
mc6821.h
mc146818rtc.h
mca-legacy.h
mca.h
mempolicy.h
mempool.h
meye.h
mii.h
minix_fs.h
miscdevice.h
mm_inline.h
mm.h
mman.h
mmtimer.h
mmzone.h
mod_devicetable.h	[PATCH] openfirmware: generate device table for userspace	2005-07-06 12:55:20 -07:00
module.h	[PATCH] modules: add version and srcversion to sysfs	2005-06-24 00:06:40 -07:00
moduleloader.h
moduleparam.h
mount.h	[PATCH] name_to_dev_t warning fix	2005-07-12 16:00:58 -07:00
mpage.h
mqueue.h
mroute.h
msdos_fs.h
msg.h
mtio.h
mv643xx.h
n_r3964.h
namei.h
namespace.h	[PATCH] namespace.c: fix race in mark_mounts_for_expiry()	2005-07-07 18:23:51 -07:00
nbd.h
ncp_fs_i.h
ncp_fs_sb.h
ncp_fs.h
ncp_mount.h
ncp_no.h
ncp.h
net.h
netdevice.h
netfilter_arp.h
netfilter_bridge.h
netfilter_decnet.h
netfilter_ipv4.h
netfilter_ipv6.h
netfilter_logging.h
netfilter.h
netlink.h	[W1]: Do not use NFLOG netlink number.	2005-07-24 19:30:28 -07:00
netpoll.h
netrom.h
nfs2.h
nfs3.h
nfs4_acl.h
nfs4_mount.h
nfs4.h	[PATCH] nfsd4: fix fh_expire_type	2005-06-24 00:06:28 -07:00
nfs_fs_i.h
nfs_fs_sb.h
nfs_fs.h
nfs_idmap.h
nfs_mount.h
nfs_page.h
nfs_xdr.h
nfs.h
nfsacl.h
nfsd_idmap.h	[PATCH] knfsd: nfsd4: idmap initialization	2005-06-24 00:06:32 -07:00
nls.h
nmi.h
node.h
nodemask.h
notifier.h
nubus.h
numa.h
nvram.h	[PATCH] drivers/char/nvram.c: possible cleanups	2005-06-25 16:25:03 -07:00
openprom_fs.h
oprofile.h
page-flags.h
pagemap.h
pagevec.h
param.h
parport_pc.h
parport.h
parser.h
patchkey.h
pci_ids.h	[PATCH] i4l: add Olitec ISDN PCI card in hisax gazel driver	2005-07-27 16:25:51 -07:00
pci-acpi.h
pci.h	[PATCH] PCI: clean up dynamic pci id logic	2005-07-01 13:35:50 -07:00
pcieport_if.h
percpu_counter.h
percpu.h
personality.h
pfkeyv2.h
pg.h
phonedev.h
pid.h
pipe_fs_i.h
pkt_cls.h	[NETLINK]: Missing padding fields in dumped structures	2005-06-28 12:56:45 -07:00
pkt_sched.h	[NETLINK]: Missing padding fields in dumped structures	2005-06-28 12:56:45 -07:00
pktcdvd.h
platform.h
pm.h	[ACPI] merge acpi-2.6.12 branch into latest Linux 2.6.13-rc...	2005-07-12 17:21:56 -04:00
pmu.h	[PATCH] ppc32: Remove CONFIG_PMAC_PBOOK	2005-06-27 15:11:43 -07:00
pnp.h
pnpbios.h
poll.h
posix_acl_xattr.h
posix_acl.h
posix_types.h
posix-timers.h
ppdev.h
ppp_channel.h
ppp_defs.h
ppp-comp.h
prctl.h
preempt.h
prefetch.h
prio_tree.h
proc_fs.h	[PATCH] kdump: Access dump file in elf format (/proc/vmcore)	2005-06-25 16:24:53 -07:00
profile.h
ps2esdi.h
ptrace.h
qic117.h
qnx4_fs.h	[PATCH] fs/qnx4/*: fix sparse warnings	2005-06-24 14:14:24 -07:00
qnxtypes.h	[PATCH] fs/qnx4/*: fix sparse warnings	2005-06-24 14:14:24 -07:00
quota.h
quotaio_v1.h
quotaio_v2.h
quotaops.h
radeonfb.h
radix-tree.h
ramfs.h
random.h
raw.h
rbtree.h
rcupdate.h
reboot_fixups.h
reboot.h	[PATCH] Add emergency_restart()	2005-07-26 14:35:41 -07:00
reiserfs_acl.h	reiserfs: run scripts/Lindent on reiserfs code	2005-07-12 20:21:28 -07:00
reiserfs_fs_i.h	reiserfs: run scripts/Lindent on reiserfs code	2005-07-12 20:21:28 -07:00
reiserfs_fs_sb.h	reiserfs: run scripts/Lindent on reiserfs code	2005-07-12 20:21:28 -07:00
reiserfs_fs.h	reiserfs: run scripts/Lindent on reiserfs code	2005-07-12 20:21:28 -07:00
reiserfs_xattr.h	reiserfs: run scripts/Lindent on reiserfs code	2005-07-12 20:21:28 -07:00
resource.h
rmap.h	[PATCH] xip: fs/mm: execute in place	2005-06-24 00:06:41 -07:00
romfs_fs.h
root_dev.h
rose.h
route.h
rslib.h
rtc.h
rtnetlink.h	[NETLINK]: Missing padding fields in dumped structures	2005-06-28 12:56:45 -07:00
rwsem-spinlock.h
rwsem.h
sc26198.h
scatterlist.h
scc.h
sched.h	[PATCH] inotify	2005-07-12 20:38:38 -07:00
sctp.h
scx200_gpio.h
scx200.h
sdla_asy.h
sdla_chdlc.h
sdla_fr.h
sdla_ppp.h
sdla_x25.h
sdla.h
sdladrv.h
sdlapci.h
sdlasfm.h
seccomp.h	[PATCH] seccomp: tsc disable	2005-06-27 15:11:44 -07:00
securebits.h
security.h
selection.h
selinux_netlink.h
sem.h
seq_file.h
seqlock.h
serial167.h
serial_8250.h	[PATCH] Serial: Split 8250 port table	2005-06-27 11:12:54 +01:00
serial_core.h	[PATCH] Serial: Move deprecation of register_serial forward to September	2005-07-16 09:30:53 +01:00
serial_reg.h
serial.h	[PATCH] Serial: Move deprecation of register_serial forward to September	2005-07-16 09:30:53 +01:00
serialP.h	[PATCH] Serial: Remove linux/version.h	2005-07-16 09:59:00 +01:00
serio.h
shm.h
shmem_fs.h
signal.h
skbuff.h	[NET]: Fix "nocast type" warnings in skbuff.h	2005-07-18 13:36:38 -07:00
slab.h	[PATCH] Really __nocast-annotate kmalloc_node()	2005-07-27 16:25:47 -07:00
smb_fs_i.h
smb_fs_sb.h
smb_fs.h
smb_mount.h
smb.h
smbno.h
smp_lock.h
smp.h
snmp.h
socket.h
sockios.h
som.h
sonet.h
sonypi.h
sort.h
sound.h
soundcard.h
spinlock.h
stallion.h
stat.h
statfs.h
stddef.h
stop_machine.h
string.h	[PATCH] propagate __nocast annotations	2005-07-07 18:23:46 -07:00
stringify.h
superhyway.h
suspend.h	[PATCH] suspend/resume SMP support	2005-06-25 16:24:32 -07:00
swap.h	[PATCH] tlb.h warning fix	2005-07-12 16:01:02 -07:00
swapops.h
synclink.h
sys.h
syscalls.h	[PATCH] move ioprio syscalls into syscalls.h	2005-07-07 18:23:37 -07:00
sysctl.h	[PATCH] s390: spin lock retry	2005-07-27 16:26:04 -07:00
sysdev.h
sysfs.h
sysrq.h
sysv_fs.h
tcp_diag.h
tcp.h	[TCP]: Move to new TSO segmenting scheme.	2005-07-05 15:24:38 -07:00
telephony.h
termios.h
textsearch_fsm.h
textsearch.h
thread_info.h
threads.h
ticable.h
time.h
timer.h
times.h
timex.h
tiocl.h
topology.h	[PATCH] sched: sched tuning	2005-06-25 16:24:42 -07:00
toshiba.h
transport_class.h
trdevice.h
tty_driver.h
tty_flip.h
tty_ldisc.h
tty.h
types.h
udf_fs_i.h
udf_fs_sb.h
udf_fs.h
udp.h
ufs_fs_i.h
ufs_fs_sb.h
ufs_fs.h
uinput.h
uio.h
ultrasound.h
umem.h
un.h
unistd.h
usb_cdc.h	[PATCH] USB: another cdc descriptor	2005-07-12 11:52:57 -07:00
usb_ch9.h	[PATCH] headers: include linux/types.h for usb_ch9.h	2005-06-28 21:20:32 -07:00
usb_gadget.h	[PATCH] USB: Fix kmalloc's flags type in USB	2005-07-12 11:52:56 -07:00
usb_gadgetfs.h
usb_isp116x.h	[PATCH] USB: Add isp116x-hcd USB host controller driver	2005-06-27 14:43:42 -07:00
usb_otg.h
usb_sl811.h
usb.h	[PATCH] USB: Fix kmalloc's flags type in USB	2005-07-12 11:52:56 -07:00
usbdevice_fs.h
user.h
utime.h
uts.h
utsname.h
vermagic.h
vfs.h
via.h
video_decoder.h
video_encoder.h
videodev2.h	[PATCH] V4L: API new webcam formats included	2005-06-28 21:20:36 -07:00
videodev.h
videotext.h
vmalloc.h
vt_buffer.h
vt_kern.h
vt.h
wait.h
wanpipe.h
wanrouter.h	[NET]: __be'ify *_type_trans()	2005-07-12 12:08:43 -07:00
watchdog.h	[PATCH] consolidate CONFIG_WATCHDOG_NOWAYOUT handling	2005-07-27 16:25:54 -07:00
wavefront.h
wireless.h
workqueue.h
writeback.h	[PATCH] rename wakeup_bdflush to wakeup_pdflush	2005-06-28 21:20:31 -07:00
x25.h
xattr.h
xfrm.h
yam.h
zconf.h
zftape.h
zlib.h
zorro_ids.h
zorro.h
zutil.h