cpufreq: Fix sysfs deadlock with concurrent hotplug/frequency switch Running one program that continuously hotplugs and replugs a cpu concurrently with another program that continuously writes to the scaling_set_speed node eventually deadlocks with:

=============================================
[ INFO: possible recursive locking detected ]
3.4.0 #37 Tainted: G        W
---------------------------------------------
filemonkey/122 is trying to acquire lock:
 (s_active#13){++++.+}, at: [<c01a3d28>] sysfs_remove_dir+0x9c/0xb4

but task is already holding lock:
 (s_active#13){++++.+}, at: [<c01a22f0>] sysfs_write_file+0xe8/0x140

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(s_active#13);
  lock(s_active#13);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by filemonkey/122:
 #0:  (&buffer->mutex){+.+.+.}, at: [<c01a2230>] sysfs_write_file+0x28/0x140
 #1:  (s_active#13){++++.+}, at: [<c01a22f0>] sysfs_write_file+0xe8/0x140

stack backtrace:
[<c0014fcc>] (unwind_backtrace+0x0/0x120) from [<c00ca600>] (validate_chain+0x6f8/0x1054)
[<c00ca600>] (validate_chain+0x6f8/0x1054) from [<c00cb778>] (__lock_acquire+0x81c/0x8d8)
[<c00cb778>] (__lock_acquire+0x81c/0x8d8) from [<c00cb9c0>] (lock_acquire+0x18c/0x1e8)
[<c00cb9c0>] (lock_acquire+0x18c/0x1e8) from [<c01a3ba8>] (sysfs_addrm_finish+0xd0/0x180)
[<c01a3ba8>] (sysfs_addrm_finish+0xd0/0x180) from [<c01a3d28>] (sysfs_remove_dir+0x9c/0xb4)
[<c01a3d28>] (sysfs_remove_dir+0x9c/0xb4) from [<c02d0e5c>] (kobject_del+0x10/0x38)
[<c02d0e5c>] (kobject_del+0x10/0x38) from [<c02d0f74>] (kobject_release+0xf0/0x194)
[<c02d0f74>] (kobject_release+0xf0/0x194) from [<c0565a98>] (cpufreq_cpu_put+0xc/0x24)
[<c0565a98>] (cpufreq_cpu_put+0xc/0x24) from [<c05683f0>] (store+0x6c/0x74)
[<c05683f0>] (store+0x6c/0x74) from [<c01a2314>] (sysfs_write_file+0x10c/0x140)
[<c01a2314>] (sysfs_write_file+0x10c/0x140) from [<c014af44>] (vfs_write+0xb0/0x128)
[<c014af44>] (vfs_write+0xb0/0x128) from [<c014b06c>] (sys_write+0x3c/0x68)
[<c014b06c>] (sys_write+0x3c/0x68) from [<c000e0e0>] (ret_fast_syscall+0x0/0x3c)

This is because store() in cpufreq.c indirectly grabs a kobject
with kobject_get() and is the last one to call kobject_put()
indirectly via cpufreq_cpu_put().

Fix this deadlock by introducing two new functions,
cpufreq_cpu_get_sysfs() and cpufreq_cpu_put_sysfs() which do the
same thing as cpufreq_cpu_{get,put}() but don't grab the kobject.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: 7668/1: fix memset-related crashes caused by recent GCC (4.7.2) optimizations Recent GCC versions (e.g. GCC-4.7.2) perform optimizations based on assumptions about the implementation of memset and similar functions. The current ARM optimized memset code does not return the value of its first argument, as is usually expected from standard implementations.

For instance in the following function:

void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
{
	memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
	waiter->magic = waiter;
	INIT_LIST_HEAD(&waiter->list);
}

compiled as:

800554d0 <debug_mutex_lock_common>:
800554d0:       e92d4008        push    {r3, lr}
800554d4:       e1a00001        mov     r0, r1
800554d8:       e3a02010        mov     r2, #16 ; 0x10
800554dc:       e3a01011        mov     r1, #17 ; 0x11
800554e0:       eb04426e        bl      80165ea0 <memset>
800554e4:       e1a03000        mov     r3, r0
800554e8:       e583000c        str     r0, [r3, #12]
800554ec:       e5830000        str     r0, [r3]
800554f0:       e5830004        str     r0, [r3, #4]
800554f4:       e8bd8008        pop     {r3, pc}

GCC assumes memset returns the value of pointer 'waiter' in register r0; causing
register/memory corruptions.

This patch fixes the return value of the assembly version of memset.
It adds a 'mov' instruction and merges an additional load+store into
existing load/store instructions.
For ease of review, here is a breakdown of the patch into 4 simple steps:

Step 1
======
Perform the following substitutions:
ip -> r8, then
r0 -> ip,
and insert 'mov ip, r0' as the first statement of the function.
At this point, we have a memset() implementation returning the proper result,
but corrupting r8 on some paths (the ones that were using ip).

Step 2
======
Make sure r8 is saved and restored when (! CALGN(1)+0) == 1:

save r8:
-       str     lr, [sp, #-4]!
+       stmfd   sp!, {r8, lr}

and restore r8 on both exit paths:
-       ldmeqfd sp!, {pc}               @ Now <64 bytes to go.
+       ldmeqfd sp!, {r8, pc}           @ Now <64 bytes to go.
(...)
        tst     r2, #16
        stmneia ip!, {r1, r3, r8, lr}
-       ldr     lr, [sp], #4
+       ldmfd   sp!, {r8, lr}

Step 3
======
Make sure r8 is saved and restored when (! CALGN(1)+0) == 0:

save r8:
-       stmfd   sp!, {r4-r7, lr}
+       stmfd   sp!, {r4-r8, lr}

and restore r8 on both exit paths:
        bgt     3b
-       ldmeqfd sp!, {r4-r7, pc}
+       ldmeqfd sp!, {r4-r8, pc}
(...)
        tst     r2, #16
        stmneia ip!, {r4-r7}
-       ldmfd   sp!, {r4-r7, lr}
+       ldmfd   sp!, {r4-r8, lr}

Step 4
======
Rewrite register list "r4-r7, r8" as "r4-r8".

Signed-off-by: Ivan Djelic <ivan.djelic@parrot.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
___________________

ARM: 7670/1: fix the memset fix
Commit 455bd4c430b0 ("ARM: 7668/1: fix memset-related crashes caused by
recent GCC (4.7.2) optimizations") attempted to fix a compliance issue
with the memset return value.  However the memset itself became broken
by that patch for misaligned pointers.

This fixes the above by branching over the entry code from the
misaligned fixup code to avoid reloading the original pointer.

Also, because the function entry alignment is wrong in the Thumb mode
compilation, that fixup code is moved to the end.

While at it, the entry instructions are slightly reworked to help dual
issue pipelines.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
ARM: perf: simplify __hw_perf_event_init err handling Currently __hw_perf_event_init has an err variable that's ignored right until the end, where it's initialised, conditionally set, and then used as a boolean flag deciding whether to return another error code.

This patch removes the err variable and simplifies the associated error
handling logic.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
______________

ARM: 7664/1: perf: remove erroneous semicolon from event initialisation
Commit 9dcbf466559f ("ARM: perf: simplify __hw_perf_event_init err
handling") tidied up the error handling code for perf event
initialisation on ARM, but a copy-and-paste error left a dangling
semicolon at the end of an if statement.

This patch removes the broken semicolon, restoring the old group
validation semantics.

Cc: Mark Rutland <mark.rutland@arm.com>
Acked-by: Dirk Behme <dirk.behme@gmail.com>
Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Added Hotplug governor

Conflicts:

	arch/arm/configs/u1_na_spr_defconfig
	compile-modules.log
	compile-zImage.log
update defconfig