tree 5ff14965af7ec10e08a0fbbbc2c6dd82c42c5c32
parent 970259bff472579204108c6f27036ec4d1206ae1
author Grygorii Strashko <grygorii.strashko@ti.com> 1447695533 +0200
committer Tony Lindgren <tony@atomide.com> 1448478200 -0800

ARM: OMAP4+: SMP: use lockless clkdm/pwrdm api in omap4_boot_secondary

OMAP CPU hotplug uses cpu1's clocks and power domains for CPU1 wake up
from low power states (or turn on CPU1). This part of code is also
part of system suspend (disable_nonboot_cpus()).
>From other side, cpu1's clocks and power domains are used by CPUIdle. All above
functionality is mutually exclusive and, therefore, lockless clkdm/pwrdm api
can be used in omap4_boot_secondary().

This fixes below back-trace on -RT which is triggered by
pwrdm_lock/unlock():

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:917
 in_atomic(): 1, irqs_disabled(): 0, pid: 118, name: sh
 9 locks held by sh/118:
  #0:  (sb_writers#4){.+.+.+}, at: [<c0144a6c>] vfs_write+0x13c/0x164
  #1:  (&of->mutex){+.+.+.}, at: [<c01b4c70>] kernfs_fop_write+0x48/0x19c
  #2:  (s_active#24){.+.+.+}, at: [<c01b4c78>] kernfs_fop_write+0x50/0x19c
  #3:  (device_hotplug_lock){+.+.+.}, at: [<c03cbff0>] lock_device_hotplug_sysfs+0xc/0x4c
  #4:  (&dev->mutex){......}, at: [<c03cd284>] device_online+0x14/0x88
  #5:  (cpu_add_remove_lock){+.+.+.}, at: [<c003af90>] cpu_up+0x50/0x1a0
  #6:  (cpu_hotplug.lock){++++++}, at: [<c003ae48>] cpu_hotplug_begin+0x0/0xc4
  #7:  (cpu_hotplug.lock#2){+.+.+.}, at: [<c003aec0>] cpu_hotplug_begin+0x78/0xc4
  #8:  (boot_lock){+.+...}, at: [<c002b254>] omap4_boot_secondary+0x1c/0x178
 Preemption disabled at:[<  (null)>]   (null)

 CPU: 0 PID: 118 Comm: sh Not tainted 4.1.12-rt11-01998-gb4a62c3-dirty #137
 Hardware name: Generic DRA74X (Flattened Device Tree)
 [<c0017574>] (unwind_backtrace) from [<c0013be8>] (show_stack+0x10/0x14)
 [<c0013be8>] (show_stack) from [<c05a8670>] (dump_stack+0x80/0x94)
 [<c05a8670>] (dump_stack) from [<c05ad158>] (rt_spin_lock+0x24/0x54)
 [<c05ad158>] (rt_spin_lock) from [<c0030dac>] (clkdm_wakeup+0x10/0x2c)
 [<c0030dac>] (clkdm_wakeup) from [<c002b2c0>] (omap4_boot_secondary+0x88/0x178)
 [<c002b2c0>] (omap4_boot_secondary) from [<c0015d00>] (__cpu_up+0xc4/0x164)
 [<c0015d00>] (__cpu_up) from [<c003b09c>] (cpu_up+0x15c/0x1a0)
 [<c003b09c>] (cpu_up) from [<c03cd2d4>] (device_online+0x64/0x88)
 [<c03cd2d4>] (device_online) from [<c03cd360>] (online_store+0x68/0x74)
 [<c03cd360>] (online_store) from [<c01b4ce0>] (kernfs_fop_write+0xb8/0x19c)
 [<c01b4ce0>] (kernfs_fop_write) from [<c0144124>] (__vfs_write+0x20/0xd8)
 [<c0144124>] (__vfs_write) from [<c01449c0>] (vfs_write+0x90/0x164)
 [<c01449c0>] (vfs_write) from [<c01451e4>] (SyS_write+0x44/0x9c)
 [<c01451e4>] (SyS_write) from [<c0010240>] (ret_fast_syscall+0x0/0x54)
 CPU1: smp_ops.cpu_die() returned, trying to resuscitate

Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>