sync_buffer() needs the mmap_sem for two distinct operations, both only
occurring upon user context switch handling:

 1) Dealing with the exe_file.

 2) Adding the dcookie data as we need to lookup the vma that
   backs it. This is done via add_sample() and add_data().

This patch isolates 1), for it will no longer need the mmap_sem for
serialization.  However, for now, make of the more standard
get_mm_exe_file(), requiring only holding the mmap_sem to read the value,
and relying on reference counting to make sure that the exe file won't
dissappear underneath us while doing the get dcookie.

As a consequence, for 2) we move the mmap_sem locking into where we really
need it, in lookup_dcookie().  The benefits are twofold: reduce mmap_sem
hold times, and cleaner code.

[akpm@linux-foundation.org: export get_mm_exe_file for arch/x86/oprofile/oprofile.ko]
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Cc: Robert Richter <rric@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This modifies the IP32 (SGI O2) platform and reset code to utilize the new
rtc-ds1685 driver.  The old mc146818rtc.h header is removed and ip32_defconfig
is updated as well.
Signed-off-by: NJoshua Kinard <kumba@gentoo.org>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Cc: Yalin Wang <yalin.wang@sonymobile.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions. The obsolete sigreturn syscall override
is retained in 32-bit mode, and the ia32 syscall overrides are used in
the compat case. Remaining definitions were identical.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions. The obsolete sigreturn in COMPAT mode
is retained as an override. Remaining definitions are identical. Also
corrected missing #define for header reinclusion protection.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions.  The obsolete sigreturn in COMPAT mode is
retained as an override.  Remaining definitions are identical, though they
incorrectly appeared in uapi, which has been corrected.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions. Definitions were identical.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions.  COMPAT definitions retain their
overrides and the remaining definitions were identical.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions. Since microblaze is 32-bit, the COMPAT
seccomp defines are unused and can be dropped. The obsolete sigreturn
for seccomp strict mode is retained as an override. Remaining definitions
are identical.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Michal Simek <monstr@monstr.eu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Switch to using the newly created asm-generic/seccomp.h for the seccomp
strict mode syscall definitions. Definitions were identical.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Most architectures don't need to do much special for the strict-mode
seccomp syscall entries.  Remove the redundant headers and reduce the
others.

This patch (of 8):

Some architectures may need to override the compat sigreturn definition,
as is already possible in the non-compat case.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
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>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: James Hogan <james.hogan@imgtec.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

print_task_path_n_nm() is local to this file, its only user being
show_regs().  Mark the function static and avoid the EXPORT_SYMBOL.
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Acked-by: NVineet Gupta <vgupta@synoipsys.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is better to use macros which are already available because then there
is just one location which needs to be change.

[akpm@linux-foundation.org: move IS_ENABLED definition to after the IS_BUILTIN and IS_MODULE definitions]
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Using the indenting we can see the curly braces were obviously intended.
This is a static checker fix, but my guess is that we don't read enough
bytes, because we don't calculate "t_len" correctly.

Fixes: f1d82698 ('memstick: use fully asynchronous request processing')
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Cc: Alex Dubov <oakad@yahoo.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In case of failed memory allocation, the return should be ENOMEM instead
of ENOSPC.

Return -EIO when sb_bread() fails.
Signed-off-by: NSanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This kthread is not loop at all due to break at the end of the loop.  Make
that function linear, with no while loop.

And remove an unnecessary cast.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Cc: Anil Gurumurthy <anil.gurumurthy@qlogic.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is a possibility of kstrdup() failure upon memory pressure.
Therefore, returning ENOMEM even for new_opts.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: NSanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: Taesoo kim <taesoo@gatech.edu>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace mount option test by affs_test_opt().
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Replace direct mount option assignation by affs_set_opt() macro.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add clear/set/test affs mount option macros.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, affs still uses direct access on mount_options.  This patch
prepares to use affs_clear/set/test_opt() like other filesystems.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the wrong values returned by various functions such as EIO and ENOMEM.
Signed-off-by: NSanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: Fabian Frederick <fabf@skynet.be>
Cc: Joe Perches <joe@perches.com>
Cc: Taesoo kim <taesoo@gatech.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

gcov profiling if enabled with other heavy compile-time instrumentation
like KASan could trigger following softlockups:

  NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]
  Modules linked in:
  irq event stamp: 22823276
  hardirqs last  enabled at (22823275): [<ffffffff86e8d10d>] mutex_lock_nested+0x7d9/0x930
  hardirqs last disabled at (22823276): [<ffffffff86e9521d>] apic_timer_interrupt+0x6d/0x80
  softirqs last  enabled at (22823172): [<ffffffff811ed969>] __do_softirq+0x4db/0x729
  softirqs last disabled at (22823167): [<ffffffff811edfcf>] irq_exit+0x7d/0x15b
  CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W       3.19.0-05245-gbb33326-dirty #3
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
  task: ffff88006cba8000 ti: ffff88006cbb0000 task.ti: ffff88006cbb0000
  RIP: kasan_mem_to_shadow+0x1e/0x1f
  Call Trace:
    strcmp+0x28/0x70
    get_node_by_name+0x66/0x99
    gcov_event+0x4f/0x69e
    gcov_enable_events+0x54/0x7b
    gcov_fs_init+0xf8/0x134
    do_one_initcall+0x1b2/0x288
    kernel_init_freeable+0x467/0x580
    kernel_init+0x15/0x18b
    ret_from_fork+0x7c/0xb0
  Kernel panic - not syncing: softlockup: hung tasks

Fix this by sticking cond_resched() in gcov_enable_events().
Signed-off-by: NAndrey Ryabinin <a.ryabinin@samsung.com>
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When converting unsigned long to int overflows may occur.  These currently
are not detected when writing to the sysctl file system.

E.g. on a system where int has 32 bits and long has 64 bits
  echo 0x800001234 > /proc/sys/kernel/threads-max
has the same effect as
  echo 0x1234 > /proc/sys/kernel/threads-max

The patch adds the missing check in do_proc_dointvec_conv.

With the patch an overflow will result in an error EINVAL when writing to
the the sysctl file system.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

cpumask_next_and() is looking for cpumask_next() in src1 in a loop and
tests if found cpu is also present in src2. remove that loop, perform
cpumask_and() of src1 and src2 first and use that new mask to find
cpumask_next().

Apart from removing while loop, ./bloat-o-meter on x86_64 shows
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8)
function                                     old     new   delta
cpumask_next_and                              62      54      -8
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Amir Vadai <amirv@mellanox.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We set sig->notify_count = -1 between RELEASE and ACQUIRE operations:

	spin_unlock_irq(lock);
	...
	if (!thread_group_leader(tsk)) {
		...
                for (;;) {
			sig->notify_count = -1;
                        write_lock_irq(&tasklist_lock);

There are no restriction on it so other processors may see this STORE
mixed with other STOREs in both areas limited by the spinlocks.

Probably, it may be reordered with the above

	sig->group_exit_task = tsk;
	sig->notify_count = zap_other_threads(tsk);

in some way.

Set it under tasklist_lock locked to be sure nothing will be reordered.
Signed-off-by: NKirill Tkhai <ktkhai@parallels.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Oleg cleverly suggested using xchg() to set the new mm->exe_file instead
of calling set_mm_exe_file() which requires some form of serialization --
mmap_sem in this case.  For archs that do not have atomic rmw instructions
we still fallback to a spinlock alternative, so this should always be
safe.  As such, we only need the mmap_sem for looking up the backing
vm_file, which can be done sharing the lock.  Naturally, this means we
need to manually deal with both the new and old file reference counting,
and we need not worry about the MMF_EXE_FILE_CHANGED bits, which can
probably be deleted in the future anyway.
Signed-off-by: NDavidlohr Bueso <dbueso@suse.de>
Suggested-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch removes mm->mmap_sem from mm->exe_file read side.
Also it kills dup_mm_exe_file() and moves exe_file duplication into
dup_mmap() where both mmap_sems are locked.

[akpm@linux-foundation.org: fix comment typo]
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

File /proc/sys/kernel/threads-max controls the maximum number of threads
that can be created using fork().

[akpm@linux-foundation.org: fix typo, per Guenter]
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Users can change the maximum number of threads by writing to
/proc/sys/kernel/threads-max.

With the patch the value entered is checked against the same limits that
apply when fork_init is called.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
THREAD_SIZE.

E.g.  architecture hexagon may have page size 1M and thread size 4096.
This would lead to a division by zero in the calculation of max_threads.

With 32-bit calculation there is no solution which delivers valid results
for all possible combinations of the parameters.  The code is only called
once.  Hence a 64-bit calculation can be used as solution.

[akpm@linux-foundation.org: use clamp_t(), per Oleg]
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PAGE_SIZE is not guaranteed to be equal to or less than 8 times the
THREAD_SIZE.

E.g.  architecture hexagon may have page size 1M and thread size 4096.
This would lead to a division by zero in the calculation of max_threads.

With this patch the buggy code is moved to a separate function
set_max_threads.  The error is not fixed.

After fixing the problem in a separate patch the new function can be
reused to adjust max_threads after adding or removing memory.

Argument mempages of function fork_init() is removed as totalram_pages is
an exported symbol.

The creation of separate patches for refactoring to a new function and for
fixing the logic was suggested by Ingo Molnar.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The comment explaining what value max_threads is set to is outdated.  The
maximum memory consumption ratio for thread structures was 1/2 until
February 2002, then it was briefly changed to 1/16 before being set to 1/8
which we still use today.  The comment was never updated to reflect that
change, it's about time.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

copy_process will report any failure in alloc_pid as ENOMEM currently
which is misleading because the pid allocation might fail not only when
the memory is short but also when the pid space is consumed already.

The current man page even mentions this case:

: EAGAIN
:
:       A system-imposed limit on the number of threads was encountered.
:       There are a number of limits that may trigger this error: the
:       RLIMIT_NPROC soft resource limit (set via setrlimit(2)), which
:       limits the number of processes and threads for a real user ID, was
:       reached; the kernel's system-wide limit on the number of processes
:       and threads, /proc/sys/kernel/threads-max, was reached (see
:       proc(5)); or the maximum number of PIDs, /proc/sys/kernel/pid_max,
:       was reached (see proc(5)).

so the current behavior is also incorrect wrt.  documentation.  POSIX man
page also suggest returing EAGAIN when the process count limit is reached.

This patch simply propagates error code from alloc_pid and makes sure we
return -EAGAIN due to reservation failure.  This will make behavior of
fork closer to both our documentation and POSIX.

alloc_pid might alsoo fail when the reaper in the pid namespace is dead
(the namespace basically disallows all new processes) and there is no
good error code which would match documented ones. We have traditionally
returned ENOMEM for this case which is misleading as well but as per
Eric W. Biederman this behavior is documented in man pid_namespaces(7)

: If the "init" process of a PID namespace terminates, the kernel
: terminates all of the processes in the namespace via a SIGKILL signal.
: This behavior reflects the fact that the "init" process is essential for
: the correct operation of a PID namespace.  In this case, a subsequent
: fork(2) into this PID namespace will fail with the error ENOMEM; it is
: not possible to create a new processes in a PID namespace whose "init"
: process has terminated.

and introducing a new error code would be too risky so let's stick to
ENOMEM for this case.
Signed-off-by: NMichal Hocko <mhocko@suse.cz>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sending SI_TKILL from rt_[tg]sigqueueinfo was deprecated, so now we issue
a warning on the first attempt of doing it.  We use WARN_ON_ONCE, which is
not informative and, what is worse, taints the kernel, making the trinity
syscall fuzzer complain false-positively from time to time.

It does not look like we need this warning at all, because the behaviour
changed quite a long time ago (2.6.39), and if an application relies on
the old API, it gets EPERM anyway and can issue a warning by itself.

So let us zap the warning in kernel.
Signed-off-by: NVladimir Davydov <vdavydov@parallels.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ptrace_detach() re-checks ->ptrace under tasklist lock and calls
release_task() if __ptrace_detach() returns true.  This was needed because
the __TASK_TRACED tracee could be killed/untraced, and it could even pass
exit_notify() before we take tasklist_lock.

But this is no longer possible after 9899d11f "ptrace: ensure
arch_ptrace/ptrace_request can never race with SIGKILL".  We can turn
these checks into WARN_ON() and remove release_task().

While at it, document the setting of child->exit_code.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Pavel Labath <labath@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ptrace_resume() is called when the tracee is still __TASK_TRACED.  We set
tracee->exit_code and then wake_up_state() changes tracee->state.  If the
tracer's sub-thread does wait() in between, task_stopped_code(ptrace => T)
wrongly looks like another report from tracee.

This confuses debugger, and since wait_task_stopped() clears ->exit_code
the tracee can miss a signal.

Test-case:

	#include <stdio.h>
	#include <unistd.h>
	#include <sys/wait.h>
	#include <sys/ptrace.h>
	#include <pthread.h>
	#include <assert.h>

	int pid;

	void *waiter(void *arg)
	{
		int stat;

		for (;;) {
			assert(pid == wait(&stat));
			assert(WIFSTOPPED(stat));
			if (WSTOPSIG(stat) == SIGHUP)
				continue;

			assert(WSTOPSIG(stat) == SIGCONT);
			printf("ERR! extra/wrong report:%x\n", stat);
		}
	}

	int main(void)
	{
		pthread_t thread;

		pid = fork();
		if (!pid) {
			assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0);
			for (;;)
				kill(getpid(), SIGHUP);
		}

		assert(pthread_create(&thread, NULL, waiter, NULL) == 0);

		for (;;)
			ptrace(PTRACE_CONT, pid, 0, SIGCONT);

		return 0;
	}

Note for stable: the bug is very old, but without 9899d11f "ptrace:
ensure arch_ptrace/ptrace_request can never race with SIGKILL" the fix
should use lock_task_sighand(child).
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reported-by: NPavel Labath <labath@google.com>
Tested-by: NPavel Labath <labath@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

'fat.h' includes <linux/buffer_head.h> which includes <linux/fs.h> which
includes all the header files required for all *.c files fat filesystem.

[akpm@linux-foundation.org: fs/fat/iode.c needs seq_file.h]
[sfr@canb.auug.org.au: put one actually necessary include file back]
Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

'*sb' never used, so let's remote it and pass inode->i_sb directly to the
MSDOS_SB.
Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>