Although they run as rpciod background tasks, under normal operation
(i.e. no SIGKILL), functions like nfs_sillyrename(), nfs4_proc_unlck()
and nfs4_do_close() want to be fully synchronous. This means that when we
exit, we want all references to the rpc_task to be gone, and we want
any dentry references etc. held by that task to be released.
For this reason these functions call __rpc_wait_for_completion_task(),
followed by rpc_put_task() in the expectation that the latter will be
releasing the last reference to the rpc_task, and thus ensuring that the
callback_ops->rpc_release() has been called synchronously.
This patch fixes a race which exists due to the fact that
rpciod calls rpc_complete_task() (in order to wake up the callers of
__rpc_wait_for_completion_task()) and then subsequently calls
rpc_put_task() without ensuring that these two steps are done atomically.
In order to avoid adding new spin locks, the patch uses the existing
waitqueue spin lock to order the rpc_task reference count releases between
the waiting process and rpciod.
The common case where nobody is waiting for completion is optimised for by
checking if the RPC_TASK_ASYNC flag is cleared and/or if the rpc_task
reference count is 1: in those cases we drop trying to grab the spin lock,
and immediately free up the rpc_task.
Those few processes that need to put the rpc_task from inside an
asynchronous context and that do not care about ordering are given a new
helper: rpc_put_task_async().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
They are only used inside kernel/ptrace.c, and have been for a long
time. We don't want to go back to the bad-old-days when architectures
did things on their own, so make them static and private.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we enable trace events to trace block actions, We use
blk_fill_rwbs_rq to analyze the corresponding actions
in request's cmd_flags, but we only choose the minor 2 bits
from it, so most of other flags(e.g, REQ_SYNC) are missing.
For example, with a sync write we get:
write_test-2409 [001] 160.013869: block_rq_insert: 3,64 W 0 () 258135 + =
8 [write_test]
Since now we have integrated the flags of both bio and request,
it is safe to pass rq->cmd_flags directly to blk_fill_rwbs and
blk_fill_rwbs_rq isn't needed any more.
With this patch, after a sync write we get:
write_test-2417 [000] 226.603878: block_rq_insert: 3,64 WS 0 () 258135 +=
8 [write_test]
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
When the per cpu timer is marked CLOCK_EVT_FEAT_C3STOP, then we only
can switch into oneshot mode, when the backup broadcast device
supports oneshot mode as well. Otherwise we would try to switch the
broadcast device into an unsupported mode unconditionally. This went
unnoticed so far as the current available broadcast devices support
oneshot mode. Seth unearthed this problem while debugging and working
around an hpet related BIOS wreckage.
Add the necessary check to tick_is_oneshot_available().
Reported-and-tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <alpine.LFD.2.00.1102252231200.2701@localhost6.localdomain6>
Cc: stable@kernel.org # .21 ->
* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
genirq: Disable the SHIRQ_DEBUG call in request_threaded_irq for now
genirq: Prevent access beyond allocated_irqs bitmap
With CONFIG_SHIRQ_DEBUG=y we call a newly installed interrupt handler
in request_threaded_irq().
The original implementation (commit a304e1b8) called the handler
_BEFORE_ it was installed, but that caused problems with handlers
calling disable_irq_nosync(). See commit 377bf1e4.
It's braindead in the first place to call disable_irq_nosync in shared
handlers, but ....
Moving this call after we installed the handler looks innocent, but it
is very subtle broken on SMP.
Interrupt handlers rely on the fact, that the irq core prevents
reentrancy.
Now this debug call violates that promise because we run the handler
w/o the IRQ_INPROGRESS protection - which we cannot apply here because
that would result in a possibly forever masked interrupt line.
A concurrent real hardware interrupt on a different CPU results in
handler reentrancy and can lead to complete wreckage, which was
unfortunately observed in reality and took a fricking long time to
debug.
Leave the code here for now. We want this debug feature, but that's
not easy to fix. We really should get rid of those
disable_irq_nosync() abusers and remove that function completely.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: stable@kernel.org # .28 -> .37
Lars-Peter Clausen pointed out:
I stumbled upon this while looking through the existing archs using
SPARSE_IRQ. Even with SPARSE_IRQ the NR_IRQS is still the upper
limit for the number of IRQs.
Both PXA and MMP set NR_IRQS to IRQ_BOARD_START, with
IRQ_BOARD_START being the number of IRQs used by the core.
In various machine files the nr_irqs field of the ARM machine
defintion struct is then set to "IRQ_BOARD_START + NR_BOARD_IRQS".
As a result "nr_irqs" will greater then NR_IRQS which then again
causes the "allocated_irqs" bitmap in the core irq code to be
accessed beyond its size overwriting unrelated data.
The core code really misses a sanity check there.
This went unnoticed so far as by chance the compiler/linker places
data behind that bitmap which gets initialized later on those affected
platforms.
So the obvious fix would be to add a sanity check in early_irq_init()
and break all affected platforms. Though that check wants to be
backported to stable as well, which will require to fix all known
problematic platforms and probably some more yet not known ones as
well. Lots of churn.
A way simpler solution is to allocate a slightly larger bitmap and
avoid the whole churn w/o breaking anything. Add a few warnings when
an arch returns utter crap.
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org # .37
Cc: Haojian Zhuang <haojian.zhuang@marvell.com>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
* 'fixes-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: make sure MAYDAY_INITIAL_TIMEOUT is at least 2 jiffies long
workqueue, freezer: unify spelling of 'freeze' + 'able' to 'freezable'
workqueue: wake up a worker when a rescuer is leaving a gcwq
Currently we return 0 in swsusp_alloc() when alloc_image_page() fails.
Fix that. Also remove unneeded "error" variable since the only
useful value of error is -ENOMEM.
[rjw: Fixed up the changelog and changed subject.]
Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: stable@kernel.org
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
MAYDAY_INITIAL_TIMEOUT is defined as HZ / 100 and depending on
configuration may end up 0 or 1. Even when it's 1, depending on when
the mayday timer is added in the current jiffy interval, it may expire
way before a jiffy has passed.
Make sure MAYDAY_INITIAL_TIMEOUT is at least two to guarantee that at
least a full jiffy has passed before calling rescuers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ray Jui <rjui@broadcom.com>
Cc: stable@kernel.org
There are two spellings in use for 'freeze' + 'able' - 'freezable' and
'freezeable'. The former is the more prominent one. The latter is
mostly used by workqueue and in a few other odd places. Unify the
spelling to 'freezable'.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Alex Dubov <oakad@yahoo.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Steven Whitehouse <swhiteho@redhat.com>
It was possible to call pmu::start() on an already running event. In
particular this lead so some wreckage as the hrtimer events would
re-initialize active timers.
This was due to throttled events being activated again by scheduling.
Scheduling in a context would add and force start events, resulting in
running events with a possible throttle status. The next tick to hit
that task will then try to unthrottle the event and call ->start() on
an already running event.
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86: Fix text_poke_smp_batch() deadlock
perf tools: Fix thread_map event synthesizing in top and record
watchdog, nmi: Lower the severity of error messages
ARM: oprofile: Fix backtraces in timer mode
oprofile: Fix usage of CONFIG_HW_PERF_EVENTS for oprofile_perf_init and friends
After executing the matching works, a rescuer leaves the gcwq whether
there are more pending works or not. This may decrease the
concurrency level to zero and stall execution until a new work item is
queued on the gcwq.
Make rescuer wake up a regular worker when it leaves a gcwq if there
are more works to execute, so that execution isn't stalled.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Ray Jui <rjui@broadcom.com>
Cc: stable@kernel.org
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
pci: use security_capable() when checking capablities during config space read
security: add cred argument to security_capable()
tpm_tis: Use timeouts returned from TPM
The wake_up_process() call in ptrace_detach() is spurious and not
interlocked with the tracee state. IOW, the tracee could be running or
sleeping in any place in the kernel by the time wake_up_process() is
called. This can lead to the tracee waking up unexpectedly which can be
dangerous.
The wake_up is spurious and should be removed but for now reduce its
toxicity by only waking up if the tracee is in TRACED or STOPPED state.
This bug can possibly be used as an attack vector. I don't think it
will take too much effort to come up with an attack which triggers oops
somewhere. Most sleeps are wrapped in condition test loops and should
be safe but we have quite a number of places where sleep and wakeup
conditions are expected to be interlocked. Although the window of
opportunity is tiny, ptrace can be used by non-privileged users and with
some loading the window can definitely be extended and exploited.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Expand security_capable() to include cred, so that it can be usable in a
wider range of call sites.
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: James Morris <jmorris@namei.org>
In commit ce6ada35bd ("security: Define CAP_SYSLOG") Serge Hallyn
introduced CAP_SYSLOG, but broke backwards compatibility by no longer
accepting CAP_SYS_ADMIN as an override (it would cause a warning and
then reject the operation).
Re-instate CAP_SYS_ADMIN - but keeping the warning - as an acceptable
capability until any legacy applications have been updated. There are
apparently applications out there that drop all capabilities except for
CAP_SYS_ADMIN in order to access the syslog.
(This is a re-implementation of a patch by Serge, cleaning the logic up
and making the code more readable)
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cdrom: support devices that have check_events but not media_changed
cfq-iosched: Don't wait if queue already has requests.
blkio-throttle: Avoid calling blkiocg_lookup_group() for root group
cfq: rename a function to give it more appropriate name
cciss: make cciss_revalidate not loop through CISS_MAX_LUNS volumes unnecessarily.
drivers/block/aoe/Makefile: replace the use of <module>-objs with <module>-y
loop: queue_lock NULL pointer derefence in blk_throtl_exit
drivers/block/Makefile: replace the use of <module>-objs with <module>-y
blktrace: Don't output messages if NOTIFY isn't set.
Both attempts at trying to allow softirq usage for
del_timer_sync() failed (produced bogus warnings),
so revert the commit for this release:
f266a5110d: lockdep, timer: Fix del_timer_sync() annotation
and try again later.
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1297174680.13327.107.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
