tick: Fix tick_broadcast_pending_mask not cleared

The recent modification in the cpuidle framework consolidated the
timer broadcast code across the different drivers by setting a new
flag in the idle state. It tells the cpuidle core code to enter/exit
the broadcast mode for the cpu when entering a deep idle state. The
broadcast timer enter/exit is no longer handled by the back-end
driver.

This change made the local interrupt to be enabled *before* calling
CLOCK_EVENT_NOTIFY_EXIT.

On a tegra114, a four cores system, when the flag has been introduced
in the driver, the following warning appeared:

WARNING: at kernel/time/tick-broadcast.c:578 tick_broadcast_oneshot_control
CPU: 2 PID: 0 Comm: swapper/2 Not tainted 3.10.0-rc3-next-20130529+ #15
[<c00667f8>] (tick_broadcast_oneshot_control+0x1a4/0x1d0) from [<c0065cd0>] (tick_notify+0x240/0x40c)
[<c0065cd0>] (tick_notify+0x240/0x40c) from [<c0044724>] (notifier_call_chain+0x44/0x84)
[<c0044724>] (notifier_call_chain+0x44/0x84) from [<c0044828>] (raw_notifier_call_chain+0x18/0x20)
[<c0044828>] (raw_notifier_call_chain+0x18/0x20) from [<c00650cc>] (clockevents_notify+0x28/0x170)
[<c00650cc>] (clockevents_notify+0x28/0x170) from [<c033f1f0>] (cpuidle_idle_call+0x11c/0x168)
[<c033f1f0>] (cpuidle_idle_call+0x11c/0x168) from [<c000ea94>] (arch_cpu_idle+0x8/0x38)
[<c000ea94>] (arch_cpu_idle+0x8/0x38) from [<c005ea80>] (cpu_startup_entry+0x60/0x134)
[<c005ea80>] (cpu_startup_entry+0x60/0x134) from [<804fe9a4>] (0x804fe9a4)

I don't have the hardware, so I wasn't able to reproduce the warning
but after looking a while at the code, I deduced the following:

 1. the CPU2 enters a deep idle state and sets the broadcast timer

 2. the timer expires, the tick_handle_oneshot_broadcast function is
    called, setting the tick_broadcast_pending_mask and waking up the
    idle cpu CPU2

 3. the CPU2 exits idle handles the interrupt and then invokes
    tick_broadcast_oneshot_control with CLOCK_EVENT_NOTIFY_EXIT which
    runs the following code:

    [...]
    if (dev->next_event.tv64 == KTIME_MAX)
            goto out;

    if (cpumask_test_and_clear_cpu(cpu,
                                 tick_broadcast_pending_mask))
            goto out;
    [...]

    So if there is no next event scheduled for CPU2, we fulfil the
    first condition and jump out without clearing the
    tick_broadcast_pending_mask.

 4. CPU2 goes to deep idle again and calls
    tick_broadcast_oneshot_control with CLOCK_NOTIFY_EVENT_ENTER but
    with the tick_broadcast_pending_mask set for CPU2, triggering the
    warning.

The issue only surfaced due to the modifications of the cpuidle
framework, which resulted in interrupts being enabled before the call
to the clockevents code. If the call happens before interrupts have
been enabled, the warning cannot trigger, because there is still the
event pending which caused the broadcast timer expiry.

Move the check for the next event below the check for the pending bit,
so the pending bit gets cleared whether an event is scheduled on the
cpu or not.

[ tglx: Massaged changelog ]

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reported-and-tested-by: Joseph Lo <josephl@nvidia.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linaro-kernel@lists.linaro.org
Link: http://lkml.kernel.org/r/1371485735-31249-1-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
perf: Disable monitoring on setuid processes for regular users

There was a a bug in setup_new_exec(), whereby
the test to disabled perf monitoring was not
correct because the new credentials for the
process were not yet committed and therefore
the get_dumpable() test was never firing.

The patch fixes the problem by moving the
perf_event test until after the credentials
are committed.

Signed-off-by: Stephane Eranian <eranian@google.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
rbd: send snapshot context with writes

Sending the right snapshot context with each write is required for
snapshots to work. Due to the ordering of calls, the snapshot context
is never set for any requests. This causes writes to the current
version of the image to be reflected in all snapshots, which are
supposed to be read-only.

This happens because rbd_osd_req_format_write() sets the snapshot
context based on obj_request->img_request. At this point, however,
obj_request->img_request has not been set yet, to the snapshot context
is set to NULL. Fix this by moving rbd_img_obj_request_add(), which
sets obj_request->img_request, before the osd request formatting
calls.

This resolves:
    http://tracker.ceph.com/issues/5465

Reported-by: Karol Jurak <karol.jurak@gmail.com>
Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>
mn10300: Allow to pass array name to get_user()

This fixes the following compile error:

CC block/scsi_ioctl.o
block/scsi_ioctl.c: In function 'sg_scsi_ioctl':
block/scsi_ioctl.c:449: error: invalid initializer

Signed-off-by: David Howells <dhowells@redhat.com>
mn10300: Use early_param() to parse "mem=" parameter

This fixes the problem that "init=" options may not be passed to kernel
correctly.

parse_mem_cmdline() of mn10300 arch gets rid of "mem=" string from
redboot_command_line. Then init_setup() parses the "init=" options from
static_command_line, which is a copy of redboot_command_line, and keeps
the pointer to the init options in execute_command variable.

Since the commit 026cee0 upstream (params: <level>_initcall-like kernel
parameters), static_command_line becomes overwritten by saved_command_line at
do_initcall_level(). Notice that saved_command_line is a command line
which includes "mem=" string.

As a result, execute_command may point to weird string by the length of
"mem=" parameter.
I noticed this problem when using the command line like this:

    mem=128M console=ttyS0,115200 init=/bin/sh

Here is the processing flow of command line parameters.
    start_kernel()
      setup_arch(&command_line)
         parse_mem_cmdline(cmdline_p)
           * strcpy(boot_command_line, redboot_command_line);
           * Remove "mem=xxx" from redboot_command_line.
           * *cmdline_p = redboot_command_line;
      setup_command_line(command_line) <-- command_line is redboot_command_line
        * strcpy(saved_command_line, boot_command_line)
        * strcpy(static_command_line, command_line)
      parse_early_param()
        strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
        parse_early_options(tmp_cmdline);
          parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
      parse_args("Booting ..", static_command_line, ...);
        init_setup() <-- save the pointer in execute_command
      rest_init()
        kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);

At this point, execute_command points to "/bin/sh" string.

    kernel_init()
      kernel_init_freeable()
        do_basic_setup()
          do_initcalls()
            do_initcall_level()
              (*) strcpy(static_command_line, saved_command_line);

Here, execute_command gets to point to "200" string !!

Signed-off-by: David Howells <dhowells@redhat.com>
UBIFS: prepare to fix a horrid bug

Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.

First of all, this means that 'file->private_data' can be freed while
'ubifs_readdir()' uses it.  But this particular patch does not fix the problem.
This patch is only a preparation, and the fix will follow next.

In this patch we make 'ubifs_readdir()' stop using 'file->f_pos' directly,
because 'file->f_pos' can be changed by '->llseek()' at any point. This may
lead 'ubifs_readdir()' to returning inconsistent data: directory entry names
may correspond to incorrect file positions.

So here we introduce a local variable 'pos', read 'file->f_pose' once at very
the beginning, and then stick to 'pos'. The result of this is that when
'ubifs_dir_llseek()' changes 'file->f_pos' while we are in the middle of
'ubifs_readdir()', the latter "wins".

Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
UBIFS: fix a horrid bug

Al Viro pointed me to the fact that '->readdir()' and '->llseek()' have no
mutual exclusion, which means the 'ubifs_dir_llseek()' can be run while we are
in the middle of 'ubifs_readdir()'.

This means that 'file->private_data' can be freed while 'ubifs_readdir()' uses
it, and this is a very bad bug: not only 'ubifs_readdir()' can return garbage,
but this may corrupt memory and lead to all kinds of problems like crashes an
security holes.

This patch fixes the problem by using the 'file->f_version' field, which
'->llseek()' always unconditionally sets to zero. We set it to 1 in
'ubifs_readdir()' and whenever we detect that it became 0, we know there was a
seek and it is time to clear the state saved in 'file->private_data'.

I tested this patch by writing a user-space program which runds readdir and
seek in parallell. I could easily crash the kernel without these patches, but
could not crash it with these patches.

Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fix from Ingo Molnar:
 "One more fix for a recently discovered bug"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Disable monitoring on setuid processes for regular users
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fix from Thomas Gleixner:
 "Correct an ordering issue in the tick broadcast code.  I really wish
  we'd get compensation for pain and suffering for each line of code we
  write to work around dysfunctional timer hardware."

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick: Fix tick_broadcast_pending_mask not cleared
Merge tag 'for-linus-20130628' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-mn10300

Pull two MN10300 fixes from David Howells:
 "The first fixes a problem with passing arrays rather than pointers to
  get_user() where __typeof__ then wants to declare and initialise an
  array variable which gcc doesn't like.

  The second fixes a problem whereby putting mem=xxx into the kernel
  command line causes init=xxx to get an incorrect value."

* tag 'for-linus-20130628' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-mn10300:
  mn10300: Use early_param() to parse "mem=" parameter
  mn10300: Allow to pass array name to get_user()
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull ubifs fixes from Al Viro:
 "A couple of ubifs readdir/lseek race fixes.  Stable fodder, really
  nasty..."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  UBIFS: fix a horrid bug
  UBIFS: prepare to fix a horrid bug
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

Pull Ceph fix from Sage Weil:
 "This is a recently spotted regression in the snapshot behavior...

  It turns out several tests weren't being run in the nightlies so this
  took a while to spot"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  rbd: send snapshot context with writes