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Al Viro f7e6ced406 [PATCH] allow delayed freeing of ctl_table_header 
Refcount the sucker; instead of freeing it by the end of unregistration
just drop the refcount and free only when it hits zero.  Make sure that
we _always_ make ->unregistering non-NULL in start_unregistering().

That allows anybody to get a reference to such puppy, preventing its
freeing and reuse.  It does *not* block unregistration.  Anybody who
holds such a reference can
	* try to grab a "use" reference (ctl_head_grab()); that will
succeeds if and only if it hadn't entered unregistration yet.  If it
succeeds, we can use it in all normal ways until we release the "use"
reference (with ctl_head_finish()).  Note that this relies on having
->unregistering become non-NULL in all cases when one starts to unregister
the sucker.
	* keep pointers to ctl_table entries; they *can* be freed if
the entire thing is unregistered.  However, if ctl_head_grab() succeeds,
we know that unregistration had not happened (and will not happen until
ctl_head_finish()) and such pointers can be used safely.

IOW, now we can have inodes under /proc/sys keep references to ctl_table
entries, protecting them with references to ctl_table_header and
grabbing the latter for the duration of operations that require access
to ctl_table.  That won't cause deadlocks, since unregistration will not
be stopped by mere keeping a reference to ctl_table_header.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-07-26 20:53:09 -04:00
..
irq use WARN() in kernel/irq/chip.c 2008-07-26 12:00:07 -07:00
power kexec jump: save/restore device state 2008-07-26 12:00:04 -07:00
time Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-24 12:55:01 -07:00
trace Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-26 13:25:47 -07:00
.gitignore
acct.c bsdacct: fix and add comments around acct_process() 2008-07-25 10:53:47 -07:00
audit_tree.c
audit.c [PATCH] remove useless argument type in audit_filter_user() 2008-06-24 23:36:35 -04:00
audit.h
auditfilter.c [PATCH] remove useless argument type in audit_filter_user() 2008-06-24 23:36:35 -04:00
auditsc.c x86_64 syscall audit fast-path 2008-07-23 17:47:32 -07:00
backtracetest.c backtrace: replace timer with tasklet + completions 2008-06-27 18:09:16 +02:00
bounds.c
capability.c security: filesystem capabilities refactor kernel code 2008-07-24 10:47:22 -07:00
cgroup_debug.c
cgroup.c make cgroup_seqfile_release() static 2008-07-26 12:00:11 -07:00
compat.c
configs.c
cpu.c workqueues: make get_online_cpus() useable for work->func() 2008-07-25 10:53:40 -07:00
cpuset.c cpuset: two minor code-cleanups 2008-07-25 10:53:38 -07:00
delayacct.c per-task-delay-accounting: update taskstats for memory reclaim delay 2008-07-25 10:53:47 -07:00
dma.c
exec_domain.c remove CONFIG_KMOD from core kernel code 2008-07-22 19:24:31 +10:00
exit.c tracehook: death 2008-07-26 12:00:09 -07:00
extable.c
fork.c tracehook: vfork-done 2008-07-26 12:00:08 -07:00
futex_compat.c
futex.c futexes: fix fault handling in futex_lock_pi 2008-06-23 13:31:15 +02:00
hrtimer.c Merge branch 'generic-ipi' into generic-ipi-for-linus 2008-07-15 21:55:59 +02:00
itimer.c
kallsyms.c kallsyms: fix potential overflow in binary search 2008-07-25 10:53:27 -07:00
Kconfig.hz sched: fix hrtick & generic-ipi dependency 2008-07-23 11:18:28 +02:00
Kconfig.preempt
kexec.c kexec jump: save/restore device state 2008-07-26 12:00:04 -07:00
kfifo.c
kgdb.c kgdb: sparse fix 2008-06-24 10:52:55 -05:00
kmod.c call_usermodehelper(): increase reliability 2008-07-25 10:53:28 -07:00
kprobes.c kprobes: remove redundant config check 2008-07-25 10:53:30 -07:00
ksysfs.c
kthread.c tracehook: wait_task_inactive 2008-07-26 12:00:09 -07:00
latencytop.c
lockdep_internals.h lockdep: add lock_class information to lock_chain and output it 2008-06-24 01:28:20 +02:00
lockdep_proc.c lockdep: add lock_class information to lock_chain and output it 2008-06-24 01:28:20 +02:00
lockdep.c Merge branch 'core/locking' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-14 14:55:13 -07:00
Makefile build kernel/profile.o only when requested 2008-07-25 10:53:27 -07:00
marker.c markers: use rcu_barrier_sched() and call_rcu_sched() 2008-07-25 10:53:45 -07:00
module.c modules: Take a shortcut for checking if an address is in a module 2008-07-22 19:24:28 +10:00
mutex-debug.c
mutex-debug.h
mutex.c __mutex_lock_common: use signal_pending_state() 2008-06-10 11:45:09 +02:00
mutex.h
notifier.c
ns_cgroup.c cgroup_clone: use pid of newly created task for new cgroup 2008-07-25 10:53:37 -07:00
nsproxy.c cgroup_clone: use pid of newly created task for new cgroup 2008-07-25 10:53:37 -07:00
panic.c Add a WARN() macro; this is WARN_ON() + printk arguments 2008-07-25 10:53:29 -07:00
params.c
pid_namespace.c bsdacct: switch from global bsd_acct_struct instance to per-pidns one 2008-07-25 10:53:47 -07:00
pid.c pidns: remove now unused find_pid function. 2008-07-25 10:53:45 -07:00
pm_qos_params.c pm_qos_params: BKL pushdown 2008-07-02 15:06:24 -06:00
posix-cpu-timers.c posix-timers: print RT watchdog message 2008-05-24 18:49:22 +02:00
posix-timers.c posix timers: release_posix_timer: kill the bogus put_task_struct(->it_process); 2008-07-25 10:53:38 -07:00
printk.c printk ratelimiting rewrite 2008-07-25 10:53:29 -07:00
profile.c build kernel/profile.o only when requested 2008-07-25 10:53:27 -07:00
ptrace.c tracehook: wait_task_inactive 2008-07-26 12:00:09 -07:00
rcuclassic.c Merge branch 'linus' into cpus4096 2008-07-16 00:29:07 +02:00
rcupdate.c Merge branch 'generic-ipi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-15 14:12:03 -07:00
rcupreempt_trace.c
rcupreempt.c Merge branch 'linus' into cpus4096 2008-07-16 00:29:07 +02:00
rcutorture.c rcu: make rcutorture even more vicious: invoke RCU readers from irq handlers (timers) 2008-06-26 09:24:33 +02:00
relay.c relay: add buffer-only channels; useful for early logging 2008-07-26 12:00:04 -07:00
res_counter.c cgroup files: convert res_counter_write() to be a cgroups write_string() handler 2008-07-25 10:53:36 -07:00
resource.c
rtmutex_common.h
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c sysdev: Pass the attribute to the low level sysdev show/store function 2008-07-21 21:55:02 -07:00
rtmutex.c
rtmutex.h
rwsem.c
sched_clock.c Merge branch 'sched/clock' into sched/devel 2008-07-14 12:19:13 +02:00
sched_cpupri.c sched: use a 2-d bitmap for searching lowest-pri CPU 2008-06-06 15:19:28 +02:00
sched_cpupri.h sched: fix the cpuprio count really 2008-06-06 15:19:44 +02:00
sched_debug.c sched: add full schedstats to /proc/sched_debug 2008-06-27 14:31:31 +02:00
sched_fair.c Merge branch 'sched/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-23 19:36:53 -07:00
sched_features.h sched: bias effective_load() error towards failing wake_affine(). 2008-06-27 14:31:47 +02:00
sched_idletask.c
sched_rt.c Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-07-24 12:53:51 -07:00
sched_stats.h sched: fix accounting in task delay accounting & migration 2008-07-04 12:50:23 +02:00
sched.c tracehook: wait_task_inactive 2008-07-26 12:00:09 -07:00
seccomp.c
semaphore.c mmiotrace broken in linux-next (8-bit writes only) 2008-07-01 10:14:06 +02:00
signal.c tracehook: force signal_pending() 2008-07-26 12:00:09 -07:00
smp.c Full conversion to early_initcall() interface, remove old interface 2008-07-26 12:00:04 -07:00
softirq.c Full conversion to early_initcall() interface, remove old interface 2008-07-26 12:00:04 -07:00
softlockup.c Full conversion to early_initcall() interface, remove old interface 2008-07-26 12:00:04 -07:00
spinlock.c
srcu.c
stacktrace.c stacktrace: fix modular build, export print_stack_trace and save_stack_trace 2008-06-30 09:20:55 +02:00
stop_machine.c cpumask: Replace cpumask_of_cpu with cpumask_of_cpu_ptr 2008-07-18 22:02:57 +02:00
sys_ni.c signalfd: fix undefined reference to `compat_sys_signalfd4' when !CONFIG_SIGNALFD 2008-07-25 11:35:41 -07:00
sys.c kexec jump 2008-07-26 12:00:04 -07:00
sysctl_check.c sysctl: check for bogus modes 2008-07-25 10:53:45 -07:00
sysctl.c [PATCH] allow delayed freeing of ctl_table_header 2008-07-26 20:53:09 -04:00
taskstats.c taskstats: remove initialization of static per-cpu variable 2008-07-25 10:53:47 -07:00
test_kprobes.c
time.c
timeconst.pl
timer.c Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2008-07-14 16:06:58 -07:00
tsacct.c tsacct: fix bacct_add_tsk()'s use of do_div() 2008-07-25 10:53:47 -07:00
uid16.c
user_namespace.c
user.c
utsname_sysctl.c
utsname.c
wait.c
workqueue.c workqueues: do CPU_UP_CANCELED if CPU_UP_PREPARE fails 2008-07-25 10:53:41 -07:00