Commit 464d6242 ("select: switch compat_{get,put}_fd_set() to
compat_{get,put}_bitmap()") changed the calculation on how many bytes
need to be zeroed when userspace handed over a NULL pointer for a fdset
array in the select syscall.

The calculation was changed in compat_get_fd_set() wrongly from
	memset(fdset, 0, ((nr + 1) & ~1)*sizeof(compat_ulong_t));
to
	memset(fdset, 0, ALIGN(nr, BITS_PER_LONG));

The ALIGN(nr, BITS_PER_LONG) calculates the number of _bits_ which need
to be zeroed in the target fdset array (rounded up to the next full bits
for an unsigned long).

But the memset() call expects the number of _bytes_ to be zeroed.

This leads to clearing more memory than wanted (on the stack area or
even at kmalloc()ed memory areas) and to random kernel crashes as we
have seen them on the parisc platform.

The correct change should have been

	memset(fdset, 0, (ALIGN(nr, BITS_PER_LONG) / BITS_PER_LONG) * BYTES_PER_LONG);

which is the same as can be archieved with a call to

	zero_fd_set(nr, fdset).

Fixes: 464d6242 ("select: switch compat_{get,put}_fd_set() to compat_{get,put}_bitmap()"
Acked-by: N: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NHelge Deller <deller@gmx.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Rename:

	wait_queue_t		=>	wait_queue_entry_t

'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.

Start sorting this out by renaming it to 'wait_queue_entry_t'.

This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

There are many code paths opencoding kvmalloc.  Let's use the helper
instead.  The main difference to kvmalloc is that those users are
usually not considering all the aspects of the memory allocator.  E.g.
allocation requests <= 32kB (with 4kB pages) are basically never failing
and invoke OOM killer to satisfy the allocation.  This sounds too
disruptive for something that has a reasonable fallback - the vmalloc.
On the other hand those requests might fallback to vmalloc even when the
memory allocator would succeed after several more reclaim/compaction
attempts previously.  There is no guarantee something like that happens
though.

This patch converts many of those places to kv[mz]alloc* helpers because
they are more conservative.

Link: http://lkml.kernel.org/r/20170306103327.2766-2-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> # Xen bits
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: Andreas Dilger <andreas.dilger@intel.com> # Lustre
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> # KVM/s390
Acked-by: Dan Williams <dan.j.williams@intel.com> # nvdim
Acked-by: David Sterba <dsterba@suse.com> # btrfs
Acked-by: Ilya Dryomov <idryomov@gmail.com> # Ceph
Acked-by: Tariq Toukan <tariqt@mellanox.com> # mlx4
Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx5
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Santosh Raspatur <santosh@chelsio.com>
Cc: Hariprasad S <hariprasad@chelsio.com>
Cc: Yishai Hadas <yishaih@mellanox.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: "Yan, Zheng" <zyan@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This patch flips the logic we were using to determine if the busy polling
has timed out.  The main motivation for this is that we will need to
support two different possible timeout values in the future and by
recording the start time rather than when we would want to end we can focus
on making the end_time specific to the task be it epoll or socket based
polling.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.
Requested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The select(2) syscall performs a kmalloc(size, GFP_KERNEL) where size grows
with the number of fds passed. We had a customer report page allocation
failures of order-4 for this allocation. This is a costly order, so it might
easily fail, as the VM expects such allocation to have a lower-order fallback.

Such trivial fallback is vmalloc(), as the memory doesn't have to be physically
contiguous and the allocation is temporary for the duration of the syscall
only. There were some concerns, whether this would have negative impact on the
system by exposing vmalloc() to userspace. Although an excessive use of vmalloc
can cause some system wide performance issues - TLB flushes etc. - a large
order allocation is not for free either and an excessive reclaim/compaction can
have a similar effect. Also note that the size is effectively limited by
RLIMIT_NOFILE which defaults to 1024 on the systems I checked. That means the
bitmaps will fit well within single page and thus the vmalloc() fallback could
be only excercised for processes where root allows a higher limit.

Note that the poll(2) syscall seems to use a linked list of order-0 pages, so
it doesn't need this kind of fallback.

[eric.dumazet@gmail.com: fix failure path logic]
[akpm@linux-foundation.org: use proper type for size]
Link: http://lkml.kernel.org/r/20160927084536.5923-1-vbabka@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct timespec is not y2038 safe.  Even though timespec might be
sufficient to represent timeouts, use struct timespec64 here as the plan
is to get rid of all timespec reference in the kernel.

The patch transitions the common functions: poll_select_set_timeout()
and select_estimate_accuracy() to use timespec64.  And, all the syscalls
that use these functions are transitioned in the same patch.

The restart block parameters for poll uses monotonic time.  Use
timespec64 here as well to assign timeout value.  This parameter in the
restart block need not change because this only holds the monotonic
timestamp at which timeout should occur.  And, unsigned long data type
should be big enough for this timestamp.

The system call interfaces will be handled in a separate series.

Compat interfaces need not change as timespec64 is an alias to struct
timespec on a 64 bit system.

Link: http://lkml.kernel.org/r/1461947989-21926-3-git-send-email-deepa.kernel@gmail.comSigned-off-by: NDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patchset introduces a /proc/<pid>/timerslack_ns interface which
would allow controlling processes to be able to set the timerslack value
on other processes in order to save power by avoiding wakeups (Something
Android currently does via out-of-tree patches).

The first patch tries to fix the internal timer_slack_ns usage which was
defined as a long, which limits the slack range to ~4 seconds on 32bit
systems.  It converts it to a u64, which provides the same basically
unlimited slack (500 years) on both 32bit and 64bit machines.

The second patch introduces the /proc/<pid>/timerslack_ns interface
which allows the full 64bit slack range for a task to be read or set on
both 32bit and 64bit machines.

With these two patches, on a 32bit machine, after setting the slack on
bash to 10 seconds:

$ time sleep 1

real    0m10.747s
user    0m0.001s
sys     0m0.005s

The first patch is a little ugly, since I had to chase the slack delta
arguments through a number of functions converting them to u64s.  Let me
know if it makes sense to break that up more or not.

Other than that things are fairly straightforward.

This patch (of 2):

The timer_slack_ns value in the task struct is currently a unsigned
long.  This means that on 32bit applications, the maximum slack is just
over 4 seconds.  However, on 64bit machines, its much much larger (~500
years).

This disparity could make application development a little (as well as
the default_slack) to a u64.  This means both 32bit and 64bit systems
have the same effective internal slack range.

Now the existing ABI via PR_GET_TIMERSLACK and PR_SET_TIMERSLACK specify
the interface as a unsigned long, so we preserve that limitation on
32bit systems, where SET_TIMERSLACK can only set the slack to a unsigned
long value, and GET_TIMERSLACK will return ULONG_MAX if the slack is
actually larger then what can be stored by an unsigned long.

This patch also modifies hrtimer functions which specified the slack
delta as a unsigned long.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Number of fds is already known based on passed list.

No functional changes.
Signed-off-by: NMateusz Guzik <mguzik@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Since set_mb() is really about an smp_mb() -- not a IO/DMA barrier
like mb() rename it to match the recent smp_load_acquire() and
smp_store_release().
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target.  This is because the
restart_block is held in the same memory allocation as the kernel stack.

Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.

Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.

It's also a decent simplification, since the restart code is more or less
identical on all architectures.

[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: NRichard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit 9745cdb3 (select: use freezable blocking call)
that triggers problems during resume from suspend to RAM on Paul Bolle's
32-bit x86 machines.  Paul says:

  Ever since I tried running (release candidates of) v3.11 on the two
  working i686s I still have lying around I ran into issues on resuming
  from suspend. Reverting 9745cdb3 (select: use freezable blocking
  call) resolves those issues.

  Resuming from suspend on i686 on (release candidates of) v3.11 and
  later triggers issues like:

  traps: systemd[1] general protection ip:b738e490 sp:bf882fc0 error:0 in libc-2.16.so[b731c000+1b0000]

  and

  traps: rtkit-daemon[552] general protection ip:804d6e5 sp:b6cb32f0 error:0 in rtkit-daemon[8048000+d000]

  Once I hit the systemd error I can only get out of the mess that the
  system is at that point by power cycling it.

Since we are reverting another freezer-related change causing similar
problems to happen, this one should be reverted as well.

References: https://lkml.org/lkml/2013/10/29/583Reported-by: NPaul Bolle <pebolle@tiscali.nl>
Fixes: 9745cdb3 (select: use freezable blocking call)
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: 3.11+ <stable@vger.kernel.org> # 3.11+

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Rename the file and correct all the places where it is included.
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Suggested by Linus:
Changed time accounting for busy-poll:
- Make it microsecond based.
- Use unsigned longs.
- Revert back to use time_after instead of time_in_range.
Reorder poll/select busy loop conditions:
- Clear busy_flag after one time we can't busy-poll.
- Only init busy_end if we actually are going to busy-poll.
Added one more missing need_resched() test.
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rename functions in include/net/ll_poll.h to busy wait.
Clarify documentation about expected power use increase.
Rename POLL_LL to POLL_BUSY_LOOP.
Add need_resched() testing to poll/select busy loops.

Note, that in select and poll can_busy_poll is dynamic and is
updated continuously to reflect the existence of supported
sockets with valid queue information.
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Time in range will fail safely if we move to a different cpu with an
extremely large clock skew.
Add time_in_range64() and convert lls to use it.

changelog:
v2
- fixed double call to sched_clock in can_poll_ll
- fixed checkpatchisms
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Change Low Latency Sockets code for select and poll so that
when LLS is disabled sched_clock() is never called.

Also, avoid sending POLL_LL to sockets if disabled.
Reported-by: NAndi Kleen <andi@firstfloor.org>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

select/poll busy-poll support.

Split sysctl value into two separate ones, one for read and one for poll.
updated Documentation/sysctl/net.txt

Add a new poll flag POLL_LL. When this flag is set, sock_poll will call
sk_poll_ll if possible. sock_poll sets this flag in its return value
to indicate to select/poll when a socket that can busy poll is found.

When poll/select have nothing to report, call the low-level
sock_poll again until we are out of time or we find something.

Once the system call finds something, it stops setting POLL_LL, so it can
return the result to the user ASAP.
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Avoid waking up every thread sleeping in a select call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Move rt scheduler definitions out of include/linux/sched.h into
new file include/linux/sched/rt.h
Signed-off-by: NClark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20130207094707.7b9f825f@riff.lanSigned-off-by: NIngo Molnar <mingo@kernel.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

simplifies a bunch of callers...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Recently, glibc made a change to suppress sign-conversion warnings in
FD_SET (glibc commit ceb9e56b3d1).  This uncovered an issue with the
kernel's definition of __NFDBITS if applications #include
<linux/types.h> after including <sys/select.h>.  A build failure would
be seen when passing the -Werror=sign-compare and -D_FORTIFY_SOURCE=2
flags to gcc.

It was suggested that the kernel should either match the glibc
definition of __NFDBITS or remove that entirely.  The current in-kernel
uses of __NFDBITS can be replaced with BITS_PER_LONG, and there are no
uses of the related __FDELT and __FDMASK defines.  Given that, we'll
continue the cleanup that was started with commit 8b3d1cda
("posix_types: Remove fd_set macros") and drop the remaining unused
macros.

Additionally, linux/time.h has similar macros defined that expand to
nothing so we'll remove those at the same time.
Reported-by: NJeff Law <law@redhat.com>
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
CC: <stable@vger.kernel.org>
Signed-off-by: NJosh Boyer <jwboyer@redhat.com>
[ .. and fix up whitespace as per akpm ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Everyone either defines it in arch thread_info.h or has TIF_RESTORE_SIGMASK
and picks default set_restore_sigmask() in linux/thread_info.h.  Kill the
ifdefs, slap #error in linux/thread_info.h to catch breakage when new ones
get merged.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

In some cases the poll() implementation in a driver has to do different
things depending on the events the caller wants to poll for.  An example
is when a driver needs to start a DMA engine if the caller polls for
POLLIN, but doesn't want to do that if POLLIN is not requested but instead
only POLLOUT or POLLPRI is requested.  This is something that can happen
in the video4linux subsystem among others.

Unfortunately, the current epoll/poll/select implementation doesn't
provide that information reliably.  The poll_table_struct does have it: it
has a key field with the event mask.  But once a poll() call matches one
or more bits of that mask any following poll() calls are passed a NULL
poll_table pointer.

Also, the eventpoll implementation always left the key field at ~0 instead
of using the requested events mask.

This was changed in eventpoll.c so the key field now contains the actual
events that should be polled for as set by the caller.

The solution to the NULL poll_table pointer is to set the qproc field to
NULL in poll_table once poll() matches the events, not the poll_table
pointer itself.  That way drivers can obtain the mask through a new
poll_requested_events inline.

The poll_table_struct can still be NULL since some kernel code calls it
internally (netfs_state_poll() in ./drivers/staging/pohmelfs/netfs.h).  In
that case poll_requested_events() returns ~0 (i.e.  all events).

Very rarely drivers might want to know whether poll_wait will actually
wait.  If another earlier file descriptor in the set already matched the
events the caller wanted to wait for, then the kernel will return from the
select() call without waiting.  This might be useful information in order
to avoid doing expensive work.

A new helper function poll_does_not_wait() is added that drivers can use
to detect this situation.  This is now used in sock_poll_wait() in
include/net/sock.h.  This was the only place in the kernel that needed
this information.

Drivers should no longer access any of the poll_table internals, but use
the poll_requested_events() and poll_does_not_wait() access functions
instead.  In order to enforce that the poll_table fields are now prepended
with an underscore and a comment was added warning against using them
directly.

This required a change in unix_dgram_poll() in unix/af_unix.c which used
the key field to get the requested events.  It's been replaced by a call
to poll_requested_events().

For qproc it was especially important to change its name since the
behavior of that field changes with this patch since this function pointer
can now be NULL when that wasn't possible in the past.

Any driver accessing the qproc or key fields directly will now fail to compile.

Some notes regarding the correctness of this patch: the driver's poll()
function is called with a 'struct poll_table_struct *wait' argument.  This
pointer may or may not be NULL, drivers can never rely on it being one or
the other as that depends on whether or not an earlier file descriptor in
the select()'s fdset matched the requested events.

There are only three things a driver can do with the wait argument:

1) obtain the key field:

	events = wait ? wait->key : ~0;

   This will still work although it should be replaced with the new
   poll_requested_events() function (which does exactly the same).
   This will now even work better, since wait is no longer set to NULL
   unnecessarily.

2) use the qproc callback. This could be deadly since qproc can now be
   NULL. Renaming qproc should prevent this from happening. There are no
   kernel drivers that actually access this callback directly, BTW.

3) test whether wait == NULL to determine whether poll would return without
   waiting. This is no longer sufficient as the correct test is now
   wait == NULL || wait->_qproc == NULL.

   However, the worst that can happen here is a slight performance hit in
   the case where wait != NULL and wait->_qproc == NULL. In that case the
   driver will assume that poll_wait() will actually add the fd to the set
   of waiting file descriptors. Of course, poll_wait() will not do that
   since it tests for wait->_qproc. This will not break anything, though.

   There is only one place in the whole kernel where this happens
   (sock_poll_wait() in include/net/sock.h) and that code will be replaced
   by a call to poll_does_not_wait() in the next patch.

   Note that even if wait->_qproc != NULL drivers cannot rely on poll_wait()
   actually waiting. The next file descriptor from the set might match the
   event mask and thus any possible waits will never happen.
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NJonathan Corbet <corbet@lwn.net>
Reviewed-by: NAl Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

The 'poll()' system call timeout parameter is supposed to be 'int', not
'long'.

Now, the reason this matters is that right now 32-bit compat mode is
broken on at least x86-64, because the 32-bit code just calls
'sys_poll()' directly on x86-64, and the 32-bit argument will have been
zero-extended, turning a signed 'int' into a large unsigned 'long'
value.

We could just introduce a 'compat_sys_poll()' function for this, and
that may eventually be what we have to do, but since the actual standard
poll() semantics is *supposed* to be 'int', and since at least on x86-64
glibc sign-extends the argument before invocing the system call (so
nobody can actually use a 64-bit timeout value in user space _anyway_,
even in 64-bit binaries), the simpler solution would seem to be to just
fix the definition of the system call to match what it should have been
from the very start.

If it turns out that somebody somehow circumvents the user-level libc
64-bit sign extension and actually uses a large unsigned 64-bit timeout
despite that not being how poll() is supposed to work, we will need to
do the compat_sys_poll() approach.
Reported-by: NThomas Meyer <thomas@m3y3r.de>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace the fd_sets in struct fdtable with an array of unsigned longs and then
use the standard non-atomic bit operations rather than the FD_* macros.

This:

 (1) Removes the abuses of struct fd_set:

     (a) Since we don't want to allocate a full fd_set the vast majority of the
     	 time, we actually, in effect, just allocate a just-big-enough array of
     	 unsigned longs and cast it to an fd_set type - so why bother with the
     	 fd_set at all?

     (b) Some places outside of the core fdtable handling code (such as
     	 SELinux) want to look inside the array of unsigned longs hidden inside
     	 the fd_set struct for more efficient iteration over the entire set.

 (2) Eliminates the use of FD_*() macros in the kernel completely.

 (3) Permits the __FD_*() macros to be deleted entirely where not exposed to
     userspace.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174954.23314.48147.stgit@warthog.procyon.org.ukSigned-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>

Remove the leftover from the commit 8ff3e8e8 ("select:
switch select() and poll() over to hrtimers").
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

On some architectures __kernel_suseconds_t is int.  On these archs struct
timeval has padding bytes at the end.  This struct is copied to userspace
with these padding bytes uninitialized.  This leads to leaking of contents
of kernel stack memory.

This bug was added with v2.6.27-rc5-286-gb773ad40.

[akpm@linux-foundation.org: avoid the memset on architectures which don't need it]
Signed-off-by: NVasiliy Kulikov <segooon@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This make epoll use hrtimers for the timeout value which prevents
epoll_wait() from timing out up to a millisecond early.

This mirrors the behavior of select() and poll().
Signed-off-by: NShawn Bohrer <shawn.bohrer@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: NDavide Libenzi <davidel@xmailserver.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make it a subsystem-specific identifier because we wish to amke it
non-static in the next patch ("epoll: make epoll_wait() use the hrtimer
range feature").

Cc: Shawn Bohrer <shawn.bohrer@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a generic implementation of the old select() syscall, which expects
its argument in a memory block and switch all architectures over to use
it.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Reviewed-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: James Morris <jmorris@namei.org>
Acked-by: NAndreas Schwab <schwab@linux-m68k.org>
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NGreg Ungerer <gerg@uclinux.org>
Acked-by: NDavid Howells <dhowells@redhat.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure compiler won't do weird things with limits.  E.g.  fetching them
twice may return 2 different values after writable limits are implemented.

I.e.  either use rlimit helpers added in commit 3e10e716 ("resource:
add helpers for fetching rlimits") or ACCESS_ONCE if not applicable.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__estimate_accuracy() was prone to integer overflow, for example if *tv ==
{2147, 483648000} on a 32 bit computer (or even for delays as small as
{429, 500000000} if the task is niced).

Because the result was already forced between 0 and 100ms, the effect of
the overflow was not too problematic, but the use of the hrtimer range
feature was not optimal in overflow cases.

This patch ensures that there can not be an integer overflow in this
function.
Signed-off-by: NGuillaume Knispel <gknispel@proformatique.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>