linux-toradex.git/kernel/fork.c, branch v3.2.9-rt16

rwlocks: Fix section mismatch

2012-03-06T16:17:55+00:00

This fixes the following build error for the preempt-rt kernel.

make kernel/fork.o
  CC      kernel/fork.o
kernel/fork.c:90: error: section of ¡tasklist_lock¢ conflicts with previous declaration
make[2]: *** [kernel/fork.o] Error 1
make[1]: *** [kernel/fork.o] Error 2

The rt kernel cache aligns the RWLOCK in DEFINE_RWLOCK by default.
The non-rt kernels explicitly cache align only the tasklist_lock in
kernel/fork.c
That can create a build conflict. This fixes the build problem by making the
non-rt kernels cache align RWLOCKs by default. The side effect is that
the other RWLOCKs are also cache aligned for non-rt.

This is a short term solution for rt only.
The longer term solution would be to push the cache aligned DEFINE_RWLOCK
to mainline. If there are objections, then we could create a
DEFINE_RWLOCK_CACHE_ALIGNED or something of that nature.

Comments? Objections?

Signed-off-by: John Kacur 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/alpine.LFD.2.00.1109191104010.23118@localhost6.localdomain6
Signed-off-by: Thomas Gleixner

sched-mmdrop-delayed.patch

2012-03-06T16:17:48+00:00

Needs thread context (pgd_lock) -> ifdeffed. workqueues wont work with
RT

Signed-off-by: Thomas Gleixner

sched-delay-put-task.patch

2012-03-06T16:17:47+00:00

Signed-off-by: Thomas Gleixner

posix-timers: thread posix-cpu-timers on -rt

2012-03-06T16:17:47+00:00

posix-cpu-timer code takes non -rt safe locks in hard irq
context. Move it to a thread.

[ 3.0 fixes from Peter Zijlstra  ]

Signed-off-by: John Stultz 
Signed-off-by: Thomas Gleixner

mm: pagefault_disabled()

2012-03-06T16:17:33+00:00

Wrap the test for pagefault_disabled() into a helper, this allows us
to remove the need for current->pagefault_disabled on !-rt kernels.

Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-3yy517m8zsi9fpsf14xfaqkw@git.kernel.org

mm: Prepare decoupling the page fault disabling logic

2012-03-06T16:17:33+00:00

Add a pagefault_disabled variable to task_struct to allow decoupling
the pagefault-disabled logic from the preempt count.

Signed-off-by: Ingo Molnar 
Signed-off-by: Thomas Gleixner

signals: Allow rt tasks to cache one sigqueue struct

2012-03-06T16:17:31+00:00

To avoid allocation allow rt tasks to cache one sigqueue struct in
task struct.

Signed-off-by: Thomas Gleixner

fs: fs_struct use seqlock

2012-03-06T16:17:29+00:00

Replace the open coded seqlock with a real one, so RT can handle it.

Signed-off-by: Thomas Gleixner 
Cc: stable-rt@vger.kernel.org

epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()

2012-03-01T00:31:23+00:00

commit d80e731ecab420ddcb79ee9d0ac427acbc187b4b upstream.

This patch is intentionally incomplete to simplify the review.
It ignores ep_unregister_pollwait() which plays with the same wqh.
See the next change.

epoll assumes that the EPOLL_CTL_ADD'ed file controls everything
f_op->poll() needs. In particular it assumes that the wait queue
can't go away until eventpoll_release(). This is not true in case
of signalfd, the task which does EPOLL_CTL_ADD uses its ->sighand
which is not connected to the file.

This patch adds the special event, POLLFREE, currently only for
epoll. It expects that init_poll_funcptr()'ed hook should do the
necessary cleanup. Perhaps it should be defined as EPOLLFREE in
eventpoll.

__cleanup_sighand() is changed to do wake_up_poll(POLLFREE) if
->signalfd_wqh is not empty, we add the new signalfd_cleanup()
helper.

ep_poll_callback(POLLFREE) simply does list_del_init(task_list).
This make this poll entry inconsistent, but we don't care. If you
share epoll fd which contains our sigfd with another process you
should blame yourself. signalfd is "really special". I simply do
not know how we can define the "right" semantics if it used with
epoll.

The main problem is, epoll calls signalfd_poll() once to establish
the connection with the wait queue, after that signalfd_poll(NULL)
returns the different/inconsistent results depending on who does
EPOLL_CTL_MOD/signalfd_read/etc. IOW: apart from sigmask, signalfd
has nothing to do with the file, it works with the current thread.

In short: this patch is the hack which tries to fix the symptoms.
It also assumes that nobody can take tasklist_lock under epoll
locks, this seems to be true.

Note:

	- we do not have wake_up_all_poll() but wake_up_poll()
	  is fine, poll/epoll doesn't use WQ_FLAG_EXCLUSIVE.

	- signalfd_cleanup() uses POLLHUP along with POLLFREE,
	  we need a couple of simple changes in eventpoll.c to
	  make sure it can't be "lost".

Reported-by: Maxime Bizon 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

writeback: remove vm_dirties and task->dirties

2011-11-17T12:49:06+00:00

They are not used any more.

Signed-off-by: Wu Fengguang