Now that the whole dcache_hash_bucket crap is gone, go all the way and
also remove the weird locking layering violations for locking the hash
buckets. Add hlist_bl_lock/unlock helpers to move the locking into the
list abstraction instead of requiring each caller to open code it.
After all allowing for the bit locks is the whole point of these helpers
over the plain hlist variant.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we are waiting for the bit-lock to be released, and are looping
over the 'cpu_relax()' should not be doing anything else - otherwise we
miss the point of trying to do the whole 'cpu_relax()'.
Do the preemption enable/disable around the loop, rather than inside of
it.
Noticed when I was looking at the code generation for the dcache
__d_drop usage, and the code just looked very odd.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The dentry hashing rules have been really quite complicated for a long
while, in odd ways. That made functions like __d_drop() very fragile
and non-obvious.
In particular, whether a dentry was hashed or not was indicated with an
explicit DCACHE_UNHASHED bit. That's despite the fact that the hash
abstraction that the dentries use actually have a 'is this entry hashed
or not' model (which is a simple test of the 'pprev' pointer).
The reason that was done is because we used the normal 'is this entry
unhashed' model to mark whether the dentry had _ever_ been hashed in the
dentry hash tables, and that logic goes back many years (commit
b3423415fb: "dcache: avoid RCU for never-hashed dentries").
That, in turn, meant that __d_drop had totally different unhashing logic
for the dentry hash table case and for the anonymous dcache case,
because in order to use the "is this dentry hashed" logic as a flag for
whether it had ever been on the RCU hash table, we had to unhash such a
dentry differently so that we'd never think that it wasn't 'unhashed'
and wouldn't be free'd correctly.
That's just insane. It made the logic really hard to follow, when there
were two different kinds of "unhashed" states, and one of them (the one
that used "list_bl_unhashed()") really had nothing at all to do with
being unhashed per se, but with a very subtle lifetime rule instead.
So turn all of it around, and make it logical.
Instead of having a DENTRY_UNHASHED bit in d_flags to indicate whether
the dentry is on the hash chains or not, use the hash chain unhashed
logic for that. Suddenly "d_unhashed()" just uses "list_bl_unhashed()",
and everything makes sense.
And for the lifetime rule, just use an explicit DENTRY_RCUACCEES bit.
If we ever insert the dentry into the dentry hash table so that it is
visible to RCU lookup, we mark it DENTRY_RCUACCESS to show that it now
needs the RCU lifetime rules. Now suddently that test at dentry free
time makes sense too.
And because unhashing now is sane and doesn't depend on where the dentry
got unhashed from (because the dentry hash chain details doesn't have
some subtle side effects), we can re-unify the __d_drop() logic and use
common code for the unhashing.
Also fix one more open-coded hash chain bit_spin_lock() that I missed in
the previous chain locking cleanup commit.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now all RCU walks fall back to reference walk when CONFIG_SECURITY
is enabled, even though just the standard capability module is active.
This is because security_inode_exec_permission unconditionally fails
RCU walks.
Move this decision to the low level security module. This requires
passing the RCU flags down the security hook. This way at least
the capability module and a few easy cases in selinux/smack work
with RCU walks with CONFIG_SECURITY=y
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: Remove the extra check in queue_requests_store
block, blk-sysfs: Fix an err return path in blk_register_queue()
block: remove stale kerneldoc member from __blk_run_queue()
block: get rid of QUEUE_FLAG_REENTER
cfq-iosched: read_lock() does not always imply rcu_read_lock()
block: kill blk_flush_plug_list() export
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (51 commits)
netfilter: ipset: Fix the order of listing of sets
ip6_pol_route panic: Do not allow VLAN on loopback
bnx2x: Fix port identification problem
r8169: add Realtek as maintainer.
ip: ip_options_compile() resilient to NULL skb route
bna: fix memory leak during RX path cleanup
bna: fix for clean fw re-initialization
usbnet: Fix up 'FLAG_POINTTOPOINT' and 'FLAG_MULTI_PACKET' overlaps.
iwlegacy: fix tx_power initialization
Revert "tcp: disallow bind() to reuse addr/port"
qlcnic: limit skb frags for non tso packet
net: can: mscan: fix build breakage in mpc5xxx_can
netfilter: ipset: set match and SET target fixes
netfilter: ipset: bitmap:ip,mac type requires "src" for MAC
sctp: fix oops while removed transport still using as retran path
sctp: fix oops when updating retransmit path with DEBUG on
net: Disable NETIF_F_TSO_ECN when TSO is disabled
net: Disable all TSO features when SG is disabled
sfc: Use rmb() to ensure reads occur in order
ieee802154: Remove hacked CFLAGS in net/ieee802154/Makefile
...
* 'timer-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
RTC: rtc-omap: Fix a leak of the IRQ during init failure
posix clocks: Replace mutex with reader/writer semaphore
We are currently using this flag to check whether it's safe
to call into ->request_fn(). If it is set, we punt to kblockd.
But we get a lot of false positives and excessive punts to
kblockd, which hurts performance.
The only real abuser of this infrastructure is SCSI. So export
the async queue run and convert SCSI over to use that. There's
room for improvement in that SCSI need not always use the async
call, but this fixes our performance issue and they can fix that
up in due time.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: xen-kbdfront - fix mouse getting stuck after save/restore
Input: estimate number of events per packet
Input: evdev - indicate buffer overrun with SYN_DROPPED
Input: document event types and codes and their intended use
Input: add KEY_IMAGES specifically for AL Image Browser
Input: twl4030_keypad - fix potential NULL dereference in twl4030_kp_probe()
Input: h3600_ts - fix error handling at connect
Input: twl4030_keypad - avoid potential NULL-pointer dereference
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: add blk_run_queue_async
block: blk_delay_queue() should use kblockd workqueue
md: fix up raid1/raid10 unplugging.
md: incorporate new plugging into raid5.
md: provide generic support for handling unplug callbacks.
md - remove old plugging code.
md/dm - remove remains of plug_fn callback.
md: use new plugging interface for RAID IO.
block: drop queue lock before calling __blk_run_queue() for kblockd punt
Revert "block: add callback function for unplug notification"
block: Enhance new plugging support to support general callbacks
next_pidmap() just quietly accepted whatever 'last' pid that was passed
in, which is not all that safe when one of the users is /proc.
Admittedly the proc code should do some sanity checking on the range
(and that will be the next commit), but that doesn't mean that the
helper functions should just do that pidmap pointer arithmetic without
checking the range of its arguments.
So clamp 'last' to PID_MAX_LIMIT. The fact that we then do "last+1"
doesn't really matter, the for-loop does check against the end of the
pidmap array properly (it's only the actual pointer arithmetic overflow
case we need to worry about, and going one bit beyond isn't going to
overflow).
[ Use PID_MAX_LIMIT rather than pid_max as per Eric Biederman ]
Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Analyzed-by: Robert Święcki <robert@swiecki.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Calculate a default based on the number of ABS axes, REL axes,
and MT slots for the device during input device registration.
Signed-off-by: Jeff Brown <jeffbrown@android.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Instead of overloading __blk_run_queue to force an offload to kblockd
add a new blk_run_queue_async helper to do it explicitly. I've kept
the blk_queue_stopped check for now, but I suspect it's not needed
as the check we do when the workqueue items runs should be enough.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
A dynamic posix clock is protected from asynchronous removal by a mutex.
However, using a mutex has the unwanted effect that a long running clock
operation in one process will unnecessarily block other processes.
For example, one process might call read() to get an external time stamp
coming in at one pulse per second. A second process calling clock_gettime
would have to wait for almost a whole second.
This patch fixes the issue by using a reader/writer semaphore instead of
a mutex.
Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/%3C20110330132421.GA31771%40riccoc20.at.omicron.at%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Now that unplugging is done differently, the unplug_fn callback is
never called, so it can be completely discarded.
Signed-off-by: NeilBrown <neilb@suse.de>
MD can't use this since it really requires us to be able to
keep more than a single piece of state for the unplug. Commit
048c9374 added the required support for MD, so get rid of this
now unused code.
This reverts commit f75664570d.
Conflicts:
block/blk-core.c
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
md/raid requires an unplug callback, but as it does not uses
requests the current code cannot provide one.
So allow arbitrary callbacks to be attached to the blk_plug.
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: make unplug timer trace event correspond to the schedule() unplug
block: let io_schedule() flush the plug inline
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
futex: Set FLAGS_HAS_TIMEOUT during futex_wait restart setup
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf_event: Fix cgrp event scheduling bug in perf_enable_on_exec()
perf: Fix a build error with some GCC versions
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix erroneous all_pinned logic
sched: Fix sched-domain avg_load calculation
* 'timer-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
RTC: rtc-mrst: follow on to the change of rtc_device_register()
RTC: add missing "return 0" in new alarm func for rtc-bfin.c
RTC: Fix s3c compile error due to missing s3c_rtc_setpie
RTC: Fix early irqs caused by calling rtc_set_alarm too early
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, amd: Disable GartTlbWlkErr when BIOS forgets it
x86, NUMA: Fix fakenuma boot failure
x86/mrst: Fix boot crash caused by incorrect pin to irq mapping
x86/ce4100: Add reg property to bridges
Linus correctly observes that the most important dispatch cases
are now done from kblockd, this isn't ideal for latency reasons.
The original reason for switching dispatches out-of-line was to
avoid too deep a stack, so by _only_ letting the "accidental"
flush directly in schedule() be guarded by offload to kblockd,
we should be able to get the best of both worlds.
So add a blk_schedule_flush_plug() that offloads to kblockd,
and only use that from the schedule() path.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: only force kblockd unplugging from the schedule() path
block: cleanup the block plug helper functions
block, blk-sysfs: Use the variable directly instead of a function call
block: move queue run on unplug to kblockd
block: kill queue_sync_plugs()
block: readd plug trace event
block: add callback function for unplug notification
block: add comment on why we save and disable interrupts in flush_plug_list()
block: fixup block IO unplug trace call
block: remove block_unplug_timer() trace point
block: splice plug list to local context
For the explicit unplugging, we'd prefer to kick things off
immediately and not pay the penalty of the latency to switch
to kblockd. So let blk_finish_plug() do the run inline, while
the implicit-on-schedule-out unplug will punt to kblockd.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
