the q->lock. As such, it can remove sources of non
preemptable unbounded work for realtime.
Reviewed-by: Oleg Nesterov
Signed-off-by: Davidlohr Bueso
---
include/linux/rcuwait.h | 63 +
kernel/exit.c | 30 +++
s survived torture testing, which is actually very handy in this case
particularly dealing with equal amount of reader and writer threads.
Applies on top of Linus' tree (4.10-rc3).
Thanks.
Davidlohr Bueso (2):
sched: Introduce rcuwait machinery
locking/percpu-rwsem: Replace waitqueue with rc
On Tue, 10 Jan 2017, Oleg Nesterov wrote:
Well, speaking of naming, rcuwait_trywake() doesn't look good to me,
rcuwait_wake_up() looks better, "try" is misleading imo. But this is
cosmetic/subjective too.
I actually added the 'try' on second thought -- in that for the particular
pcpu-rwsem use
Gents, any further thoughts on this?
Thanks,
Davidlohr
While the wakeup path seems to be set up, this waitqueue is actually
never used as no-one enqueues themselves on the list. As such, wakeups
are meaningless without waiters, so lets just get rid of the whole
thing.
Signed-off-by: Davidlohr Bueso
---
drivers/media/usb/usbvision/usbvision-core.c
this bug is theoretical, there have been other offenders of the lockless
waitqueue_active() in the past -- this is also documented in the call itself.
Signed-off-by: Davidlohr Bueso
---
mm/compaction.c | 7 +++
1 file changed, 7 insertions(+)
diff --git a/mm/compaction.c b/mm/compact
27;m missing an linux/rcuwait.h include there. Here's v2, thanks.
-8<----
From: Davidlohr Bueso
Subject: [PATCH v2 1/2] sched: Introduce rcuwait machinery
rcuwait provides support for (single) rcu-safe task wait/wake functionality,
with the cav
an issue:
https://lkml.org/lkml/2016/12/30/230
Cc: Greg Kroah-Hartman
Signed-off-by: Davidlohr Bueso
---
drivers/tty/tty_ldsem.c | 18 --
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/drivers/tty/tty_ldsem.c b/drivers/tty/tty_ldsem.c
index 1bf8ed13f827
( 18.01%)
Hmeanunlink1-processes-26516400.97 ( 0.00%)16115.22 ( -1.74%)
Hmeanunlink1-processes-29614388.60 ( 0.00%)16216.13 ( 12.70%)
Hmeanunlink1-processes-32015771.85 ( 0.00%)15905.96 ( 0.85%)
Signed-off-by: Davidlohr Bueso
---
XXX: things like semaphore.c
to 50ms increase), ppc was more constant.
Signed-off-by: Davidlohr Bueso
---
arch/um/drivers/random.c | 2 +-
drivers/md/dm-bufio.c | 2 +-
drivers/md/dm-crypt.c | 4 ++--
drivers/md/persistent-data/dm-block-m
ppc64 -- arm64 is no longer
an issue:
https://lkml.org/lkml/2016/12/30/230
Signed-off-by: Davidlohr Bueso
---
XXX: do_exit() could further be cleaned up and we'd endup getting
rid of tsk for a lot of the exit_*() calls.
kernel/exit.c | 22 +++---
1 file changed, 11 inser
making it very obvious that we are indeed calling
upon the current task. There are other users left with this pattern that
could be cleaned up later.
Applies against v4.10-rc2.
[1] https://lkml.org/lkml/2016/12/30/230
Thanks.
Davidlohr Bueso (4):
kernel/exit: Compute current directly
drive
On Tue, 03 Jan 2017, Mark Rutland wrote:
Does the below help?
It does, yes. Performance is pretty much the same with either function
without sysreg. With arm no longer in the picture, I'll send up another
patchset with this change as well as Peter's cleanup remarks.
Thanks,
Davidlohr
et rid of the interface (and improve performance on
other archs) at the expense of arm64? Can arm64 do better?
Applies against v4.10-rc1.
Signed-off-by: Davidlohr Bueso
---
arch/um/drivers/random.c | 2 +-
drivers/md/dm-bufio.c | 2 +-
drivers/
Given that the arch does not add its own implementations, simply
use the asm-generic/current.h (generic-y) header instead of
duplicating code.
Signed-off-by: Davidlohr Bueso
---
arch/alpha/include/asm/Kbuild| 1 +
arch/alpha/include/asm/current.h | 9 -
2 files changed, 1 insertion
... it's already using the generic version anyways, so just
drop the file as do the other archs that do not implement
their own version of the current macro.
Signed-off-by: Davidlohr Bueso
---
arch/score/include/asm/Kbuild| 1 +
arch/score/include/asm/current.h | 6 --
2 files ch
Given that the arch does not add its own implementations, simply
use the asm-generic/current.h (generic-y) header instead of
duplicating code.
Signed-off-by: Davidlohr Bueso
---
arch/m32r/include/asm/Kbuild| 1 +
arch/m32r/include/asm/current.h | 15 ---
2 files changed, 1
Given that the arch does not add its own implementations, simply
use the asm-generic/current.h (generic-y) header instead of
duplicating code.
Signed-off-by: Davidlohr Bueso
---
arch/parisc/include/asm/Kbuild| 1 +
arch/parisc/include/asm/current.h | 15 ---
2 files changed, 1
Given that the arch does not add its own implementations, simply
use the asm-generic/current.h (generic-y) header instead of
duplicating code.
Signed-off-by: Davidlohr Bueso
---
arch/cris/include/asm/Kbuild| 1 +
arch/cris/include/asm/current.h | 15 ---
2 files changed, 1
aling with equal amount of reader and writer threads.
Thanks.
Davidlohr Bueso (2):
sched: Introduce rcuwait machinery
locking/percpu-rwsem: Replace waitqueue with rcuwait
include/linux/percpu-rwsem.h | 8 +++---
include/linux/rcuwait.h | 63 +++
k
the q->lock.
Signed-off-by: Davidlohr Bueso
---
include/linux/rcuwait.h | 63 +
kernel/exit.c | 29 +++
2 files changed, 92 insertions(+)
create mode 100644 include/linux/rcuwait.h
diff --git a/include/linux/rcu
a writer
can wait for its turn to take the lock. As such, we can avoid the
queue handling and locking overhead.
Signed-off-by: Davidlohr Bueso
---
include/linux/percpu-rwsem.h | 8
kernel/locking/percpu-rwsem.c | 7 +++
2 files changed, 7 insertions(+), 8 deletions(-)
diff --git a
Commit-ID: 9de3ffa1b714e6b8ebc1723f71bc9172a4470f7d
Gitweb: http://git.kernel.org/tip/9de3ffa1b714e6b8ebc1723f71bc9172a4470f7d
Author: Davidlohr Bueso
AuthorDate: Thu, 15 Dec 2016 11:36:24 -0800
Committer: Arnaldo Carvalho de Melo
CommitDate: Tue, 20 Dec 2016 09:37:40 -0300
perf bench
Nit: the title is a bit unclear. How about:
ipc/sem.: fix semop() locking imbalance
Otherwise, Ack.
Thanks,
Davidlohr
On Sat, 17 Dec 2016, Johanna Abrahamsson wrote:
I will try to investigate this further but as I have limited knowledge of RCU
and how the kernel works with semaphores don't expect any miracles :)
Please see if this helps: https://lkml.org/lkml/2016/12/18/79
Thanks,
Davidlohr
On Sun, 18 Dec 2016, Bueso wrote:
On Fri, 16 Dec 2016, Dmitry Vyukov wrote:
[ BUG: bad unlock balance detected! ]
4.9.0+ #89 Not tainted
Thanks for the report, I can reproduce the issue as of (which I obviously
should have tested with lockdep):
370b262c896 (ipc/sem: avoid idr tree lookup fo
On Fri, 16 Dec 2016, Dmitry Vyukov wrote:
[ BUG: bad unlock balance detected! ]
4.9.0+ #89 Not tainted
Thanks for the report, I can reproduce the issue as of (which I obviously
should have tested with lockdep):
370b262c896 (ipc/sem: avoid idr tree lookup for interrupted semop)
I need to thin
Obvious copy/paste typo from the requeue program.
Signed-off-by: Davidlohr Bueso
---
tools/perf/bench/futex-lock-pi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/bench/futex-lock-pi.c b/tools/perf/bench/futex-lock-pi.c
index 465012b320ee..6d9d6c40a916 100644
On Mon, 05 Dec 2016, Oleg Nesterov wrote:
Yes. But percpu_down_write() should not be used after exit_notify(), so we
can rely on rcu_read_lock(), release_task()->call_rcu(delayed_put_task_struct)
can't be called until an exiting task passes exit_notify().
But then we probably need WARN_ON(curre
spinlock fastpath, so it wouldn't be a very big an impact).
Signed-off-by: Davidlohr Bueso
---
include/linux/percpu-rwsem.h | 5 ++---
kernel/locking/percpu-rwsem.c | 26 +-
2 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/include/linux/percpu-rwse
On Wed, 30 Nov 2016, Greg KH wrote:
What changed from v1? Please always include it below the --- line to
keep maintainer's semi-sane.
If anything changed I would have -- this is only the From != SoB thing
you were complaining about. There's nothing to try again, this is a trivial.
:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso
---
drivers/usb/class/cdc-wdm.c | 2 +-
drivers/usb/core/devio.c| 2 +-
drivers/usb/core/sysfs.c
:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso
---
drivers/base/core.c | 2 +-
drivers/base/power/runtime.c | 4 ++--
2 files changed, 3
On Mon, 21 Nov 2016, Oleg Nesterov wrote:
On 11/21, Oleg Nesterov wrote:
No, no, I meant that afaics both readers can see per_cpu_sum() != 0 and
thus the writer won't be woken up. Till the next down_read/up_read.
Suppose that we have 2 CPU's, both counters == 1, both readers decrement.
its co
On Mon, 21 Nov 2016, Oleg Nesterov wrote:
On 11/18, Davidlohr Bueso wrote:
@@ -12,7 +12,7 @@ struct percpu_rw_semaphore {
struct rcu_sync rss;
unsigned int __percpu *read_count;
struct rw_semaphore rw_sem;
- wait_queue_head_t writer
Hi Greg!
On Sun, 20 Nov 2016, Greg KH wrote:
On Sat, Nov 19, 2016 at 11:54:25AM -0800, Davidlohr Bueso wrote:
With the new standardized functions, we can replace all ACCESS_ONCE()
calls across relevant drivers/usb/.
ACCESS_ONCE() does not work reliably on non-scalar types. For example
gcc
:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso
---
drivers/usb/class/cdc-wdm.c | 2 +-
drivers/usb/core/devio.c| 2 +-
drivers/usb/core
:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso
---
drivers/base/core.c | 2 +-
drivers/base/power/runtime.c | 4 ++--
2 files changed, 3
) step:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Update the new calls regardless of if it is a scalar type, this is
cleaner than having three alternatives.
Signed-off-by: Davidlohr Bueso
---
security/keys/keyring.c | 12 ++--
1 file changed, 6 insertions(+), 6 deletions(-)
diff
Although this is rather useless and the actual code is orders
of magnitude more detailed and informative than this document.
Might as well keep it instead, I guess its already there and
could give a user a quick why/when use them vs regular rwsems.
Signed-off-by: Davidlohr Bueso
In the case of the percpu-rwsem, they don't need any of the
fancy/bulky features, such as custom callbacks or fine grained
wakeups.
Users that can convert to simple wait-queues are encouraged to
do so for the various rt and (indirect) performance benefits.
Signed-off-by: Davidlohr
s
to these optimizations.
Passed kernel builds with lockdep, as well as an overnight run doing
locktoture.
Thanks.
Davidlohr Bueso (3):
locking/percpu-rwsem: Move text file into Documentation/locking/
locking/percpu-rwsem: Replace bulky wait-queues with swait
locking/percpu-rwsem: Avoid unnecess
every reader up().
Signed-off-by: Davidlohr Bueso
---
kernel/locking/percpu-rwsem.c | 72 ---
1 file changed, 40 insertions(+), 32 deletions(-)
diff --git a/kernel/locking/percpu-rwsem.c b/kernel/locking/percpu-rwsem.c
index cb71201855f2..8e6fbf117f14
On Thu, 17 Nov 2016, Waiman Long wrote:
Currently the wake_q data structure is defined by the WAKE_Q() macro.
This macro, however, looks like a function doing something as "wake" is
a verb. Even checkpatch.pl was confused as it reported warnings like
WARNING: Missing a blank line after declara
Hi,
Here are two small updates to semop(2), suggested a while ago by Manfred.
Both patches have passed the usual regression tests, including ltp and
some sysvsem benchmarks.
Thanks!
Davidlohr Bueso (2):
ipc/sem: simplify wait-wake loop
ipc/sem: avoid idr tree lookup for interrupted semop
indented.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 107 ++
1 file changed, 51 insertions(+), 56 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index ebd18a7104fd..a5eaf517c8b4 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1980,71 +1980,66
_lock() altogether.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 37 +
1 file changed, 5 insertions(+), 32 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index a5eaf517c8b4..11cdec301167 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -431,29 +431,6 @@ static inline
On Sat, 29 Oct 2016, Eric Wheeler wrote:
Kent, Davidlohr, does 3312845 need to land in 4.9 for some reason?
No, not particularly. I can do my stuff whenever this is ends up being merged.
Thanks,
Davidlohr
On Fri, 28 Oct 2016, Pan Xinhui wrote:
/*
* If we need to reschedule bail... so we can block.
+* Use vcpu_is_preempted to detech lock holder preemption issue
^^ detect
+ * and break.
Could you please
On Fri, 28 Oct 2016, Colin King wrote:
Thanks.
Commit-ID: 60758d6668b3e2fa8e5fd143d24d0425203d007e
Gitweb: http://git.kernel.org/tip/60758d6668b3e2fa8e5fd143d24d0425203d007e
Author: Davidlohr Bueso
AuthorDate: Mon, 24 Oct 2016 13:56:53 -0700
Committer: Arnaldo Carvalho de Melo
CommitDate: Tue, 25 Oct 2016 09:50:53 -0300
perf bench
Commit-ID: e2e1680fda1573ebfdd6bba5d58f978044746993
Gitweb: http://git.kernel.org/tip/e2e1680fda1573ebfdd6bba5d58f978044746993
Author: Davidlohr Bueso
AuthorDate: Mon, 24 Oct 2016 13:56:52 -0700
Committer: Arnaldo Carvalho de Melo
CommitDate: Tue, 25 Oct 2016 09:50:47 -0300
perf bench
This gets rid of oddities such as:
perf bench futex hash -t -4
perf: calloc: Cannot allocate memory
Runtime (and many more) are equally busted, ie run for bogus amounts
of time. Just use the abs, instead of, for example erroring out.
Signed-off-by: Davidlohr Bueso
---
tools/perf/bench/futex
Hi Arnaldo, here's the requested patch that gets rid of the struct alignment
tackling the main source of cacheline bouncing. In addition a small fix to
bogus inputs.
Thanks!
Davidlohr Bueso (2):
perf/bench-futex: Avoid worker cacheline bouncing
perf/bench-futex: Sanitize numeric param
Reported-by: Sebastian Andrzej Siewior
Acked-by: Sebastian Andrzej Siewior
Signed-off-by: Davidlohr Bueso
---
tools/perf/bench/futex-hash.c| 11 +--
tools/perf/bench/futex-lock-pi.c | 4 +++-
2 files changed, 8 insertions(+), 7 deletions(-)
diff --git a/tools/perf/bench/futex-hash.c
On 2016-10-24 09:20, Arnaldo Carvalho de Melo wrote:
From: Sebastian Andrzej Siewior
It popped up in perf testing that the worker consumes some amount of
CPU. It boils down to the increment of `ops` which causes cache line
bouncing between the individual threads.
This patch aligns the struct b
Any comments? can this make it for v4.10?
Thanks,
Davidlohr
On Wed, 19 Oct 2016, Peter Zijlstra wrote:
Subject: sched: Better explain sleep/wakeup
From: Peter Zijlstra
Date: Wed Oct 19 15:45:27 CEST 2016
There were a few questions wrt how sleep-wakeup works. Try and explain
it more.
Requested-by: Will Deacon
Signed-off-by: Peter Zijlstra (Intel)
---
On Mon, 17 Oct 2016, Sebastian Andrzej Siewior wrote:
+#ifdef HAVE_LIBNUMA_SUPPORT
+#include
+#endif
In futex.h
+static int numa_node = -1;
In futex.h (perhaps rename to futexbench_numa_node?)
+#ifndef HAVE_LIBNUMA_SUPPORT
+static int numa_run_on_node(int node __maybe_unused) { return 0
On Wed, 19 Oct 2016, Sebastian Andrzej Siewior wrote:
On 2016-10-19 11:16:16 [-0700], Davidlohr Bueso wrote:
On Mon, 17 Oct 2016, Sebastian Andrzej Siewior wrote:
> By default the application uses malloc() and all available CPUs. This
> patch introduces NUMA support which means:
> -
On Wed, 19 Oct 2016, Sebastian Andrzej Siewior wrote:
On 2016-10-19 10:59:33 [-0700], Davidlohr Bueso wrote:
Sebastian noted that overhead for worker thread ops (throughput)
accounting was producing 'perf' to appear in the profiles, consuming
a non-trivial (ie 13%) amount of CPU. T
On Mon, 17 Oct 2016, Sebastian Andrzej Siewior wrote:
By default the application uses malloc() and all available CPUs. This
patch introduces NUMA support which means:
- memory is allocated node local via numa_alloc_local()
- all CPUs of the specified NUMA node are used. This is also true if the
ocal copy and updating the actual worker once
done running, and ready to show the program summary. There is no
danger of the worker being concurrent, so we can trust that no stale
value is being seen by another thread.
Reported-by: Sebastian Andrzej Siewior
Signed-off-by: Davidlohr Bueso
---
This
end of the function.
The following makes 'perf' pretty much disappear in the profile.
Thanks,
Davidlohr
8<------
From: Davidlohr Bueso
Subject: [PATCH] perf/bench-futex: Avoid worker cacheline bouncing
Sebastian noted that overhead for worker thread ops (throughput)
accou
On Fri, 07 Oct 2016, Peter Zijlstra wrote:
+/*
+ * Optimistic trylock that only works in the uncontended case. Make sure to
+ * follow with a __mutex_trylock() before failing.
+ */
+static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
+{
+ unsigned long curr = (unsigned long
change for the later.
Signed-off-by: Davidlohr Bueso
---
XXX: This obviously needs a lot of testing.
include/asm-generic/barrier.h | 9 ++
include/linux/osq_lock.h | 10 ++
kernel/locking/mutex.c| 6 +-
kernel/locking/osq_lock.c | 279 +++---
On Fri, 07 Oct 2016, Dave Chinner wrote:
Except that it's DAX
Duh, of course; silly me.
Thanks,
Davidlohr
On Thu, 18 Aug 2016, Waiman Long wrote:
Currently, when down_read() fails, the active read locking isn't undone
until the rwsem_down_read_failed() function grabs the wait_lock. If the
wait_lock is contended, it may takes a while to get the lock. During
that period, writer lock stealing will be d
On Wed, 05 Oct 2016, Waiman Long wrote:
diff --git a/kernel/locking/osq_lock.c b/kernel/locking/osq_lock.c
index 05a3785..1e6823a 100644
--- a/kernel/locking/osq_lock.c
+++ b/kernel/locking/osq_lock.c
@@ -12,6 +12,23 @@
*/
static DEFINE_PER_CPU_SHARED_ALIGNED(struct optimistic_spin_node,
osq_n
On Wed, 05 Oct 2016, Peter Zijlstra wrote:
On Tue, Oct 04, 2016 at 06:02:14PM -0700, Davidlohr Bueso wrote:
On Mon, 03 Oct 2016, Peter Zijlstra wrote:
>Do people have more/better futex-pi test cases?
pi_stress.
Where does one find that? Link?
Sorry, git://git.kernel.org/pub/scm/li
On Mon, 03 Oct 2016, Peter Zijlstra wrote:
futex_top_waiter() returns the top-waiter on the pi_mutex. Assinging
this to a variable 'match' totally obscures the code.
Signed-off-by: Peter Zijlstra (Intel)
Reviewed-by: Davidlohr Bueso
On Mon, 03 Oct 2016, Peter Zijlstra wrote:
Since the futex_q can dissapear the instruction after assigning NULL,
this really should be a RELEASE barrier. That stops loads from hitting
dead memory too.
Signed-off-by: Peter Zijlstra (Intel)
---
kernel/futex.c |3 +--
1 file changed, 1 inserti
On Mon, 03 Oct 2016, Peter Zijlstra wrote:
These are unused and clutter up the code.
Signed-off-by: Peter Zijlstra (Intel)
Reviewed-by: Davidlohr Bueso
On Mon, 03 Oct 2016, Peter Zijlstra wrote:
Hi,
During my last PI failing patch set it became obvious there's a number of
related fail in FUTEX_UNLOCK_PI that needed sorting before we can move on
with that stuff.
These here patches are the result of staring at that code for a wee bit.
Please
On Thu, 18 Aug 2016, Waiman Long wrote:
The osq_lock() and osq_unlock() function may not provide the necessary
acquire and release barrier in some cases. This patch makes sure
that the proper barriers are provided when osq_lock() is successful
or when osq_unlock() is called.
But why do we need
71.42 (-44.04%)
Stddev 3031981.43 ( 0.00%)42306.07 ( 32.28%)
Stddev 4821317.95 ( 0.00%)42608.50 ( 99.87%)
Stddev 6423433.99 ( 0.00%)21502.56 ( -8.24%)
Signed-off-by: Davidlohr Bueso
---
Changes from v1: Stop spinning and block if we are no longer the
top-waiter for the
0.00%)42306.07 ( 32.28%)
Stddev 4821317.95 ( 0.00%)42608.50 ( 99.87%)
Stddev 6423433.99 ( 0.00%)21502.56 ( -8.24%)
Signed-off-by: Davidlohr Bueso
---
Hi, so I've rebased the patch against -tip, and has survived about a full day
of pistress pounding. That said, I
On Thu, 22 Sep 2016, Waiman Long wrote:
BTW, my initial attempt for the new futex was to use the same workflow
as the PI futexes, but use mutex which has optimistic spinning instead
of rt_mutex.
Btw, Thomas, do you still have any interest pursuing this for rtmutexes from
-rt into mainline? If
On Thu, 22 Sep 2016, Thomas Gleixner wrote:
On Thu, 22 Sep 2016, Davidlohr Bueso wrote:
On Thu, 22 Sep 2016, Thomas Gleixner wrote:
> Also what's the reason that we can't do probabilistic spinning for
> FUTEX_WAIT and have to add yet another specialized variant of futexes?
On Thu, 22 Sep 2016, Thomas Gleixner wrote:
On Thu, 22 Sep 2016, Peter Zijlstra wrote:
On Wed, Sep 21, 2016 at 07:37:34PM -0400, Waiman Long wrote:
> On 09/21/2016 02:59 AM, Mike Galbraith wrote:
> >On Tue, 2016-09-20 at 09:42 -0400, Waiman Long wrote:
> >>This patch introduces a new futex impl
On Sun, 18 Sep 2016, Manfred Spraul wrote:
Just as with msgrcv (along with the rest of sysvipc since a few years
ago), perform the security checks without holding the ipc object lock.
Thinking about it: isn't this wrong?
CPU1:
* msgrcv()
* ipcperms()
CPU2:
* msgctl(), change permissions
*
array variable to based on the sem_num
we are working on.
In addition add some comments to when we expect to the caller
to block.
Signed-off-by: Davidlohr Bueso
---
Change from v2: Improved dup detection for working on larger sets
as well as support for test-for-zero-and-increase.
ipc/sem.c | 111
On Mon, 19 Sep 2016, Manfred Spraul wrote:
On 09/18/2016 09:11 PM, Davidlohr Bueso wrote:
Davidlohr Bueso (5):
ipc/sem: do not call wake_sem_queue_do() prematurely
The only patch that I don't like.
Especially: patch 2 of the series removes the wake_up_q from the
function epilogue.
So
loads on their way out
of the call as it is not deeply nested.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 19 ---
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 5e318c5f749d..a4e8bb2fae38 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
The compiler already does this, but make it explicit. This helper
is really small and also used in update_queue's main loop, which is
O(N^2) scanning. Inline and avoid the function overhead.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
5735.00 ( 0.00%) 1040313.00 ( 7.72%)
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 265 --
1 file changed, 85 insertions(+), 180 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index a4e8bb2fae38..4d836035f9bb 100644
--- a/ipc/sem.c
+++ b/ipc
m/manfred-colorfu/ipcsemtest)
- ipcscale (https://github.com/manfred-colorfu/ipcscale)
Details are in each individual patch. Please consider for v4.9.
Thanks!
Davidlohr Bueso (5):
ipc/sem: do not call wake_sem_queue_do() prematurely
ipc/sem: rework task wakeups
ipc/sem: optimize perform_atomic_s
when we expect to the caller
to block.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 103 --
1 file changed, 94 insertions(+), 9 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 4d836035f9bb..e868b5933ff8 100644
--- a/ipc/sem.c
... saves some LoC and looks cleaner than re-implementing the
calls.
Acked-by: Manfred Spraul
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 38 +-
1 file changed, 13 insertions(+), 25 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 89adba51e85f
On Sun, 18 Sep 2016, Manfred Spraul wrote:
+ Why this empty line?
That's my fat fingers, will remove it.
+ }
+
+ sem_unlock(sma, locknum);
+ rcu_read_unlock();
+ wake_up_q(&wake_q);
+
+ goto
On Tue, 13 Sep 2016, Manfred Spraul wrote:
+ if ((error = queue.status) != -EINTR && !signal_pending(current)) {
+ /*
+* User space could assume that semop() is a memory barrier:
+* Without the mb(), the cpu could speculatively read in user
+
On Mon, 12 Sep 2016, Manfred Spraul wrote:
This patch proposes still iterating the set twice, but the first
scan is read-only, and we perform the actual updates afterward,
once we know that the call will succeed. In order to not suffer
from the overhead of dealing with sops that act on the same
On Tue, 13 Sep 2016, Manfred Spraul wrote:
- if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO))
- goto out_rcu_wakeup;
+ if (ipcperms(ns, &sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) {
+ rcu_read_unlock();
+ goto out_free;
+ }
5735.00 ( 0.00%) 1040313.00 ( 7.72%)
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 268 +++---
1 file changed, 83 insertions(+), 185 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index a4e8bb2fae38..86467b5b78ad 100644
--- a/ipc/sem.c
... saves some LoC and looks cleaner than re-implementing the
calls.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 38 +-
1 file changed, 13 insertions(+), 25 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 3774b21c54d4..64c9d143b300 100644
--- a/ipc
loads on their way out
of the call as it is not deeply nested.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 19 ---
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index 5e318c5f749d..a4e8bb2fae38 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
The compiler already does this, but make it explicit. This helper
is really small and also used in update_queue's main loop, which is
O(N^2) scanning. Inline and avoid the function overhead.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
common case.
In addition add some comments to when we expect to the caller
to block.
Signed-off-by: Davidlohr Bueso
---
ipc/sem.c | 89 ++-
1 file changed, 82 insertions(+), 7 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index
ased.
The patchset has survived the following testscases:
- ltp
- ipcsemtest (https://github.com/manfred-colorfu/ipcsemtest)
- ipcscale (https://github.com/manfred-colorfu/ipcscale)
Details are in each individual patch. Please consider for v4.9.
Thanks!
Davidlohr Bueso (5):
ipc/sem: d
mode_enter(), which is
kind of mixing core spinlocking and core sysv sems. But anyway,
this will be the patch that we _don't_ backport to stable, right?
Reviewed-by: Davidlohr Bueso
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