linux/arch/arm
Paul E. McKenney 0b9a29add4 arm: Use _rcuidle tracepoint to allow use from idle
Testing on ARM encountered the following pair of lockdep-RCU splats:

------------------------------------------------------------------------

===============================
[ INFO: suspicious RCU usage. ]
4.6.0-rc4-next-20160422 #1 Not tainted
-------------------------------
include/trace/events/power.h:328 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

RCU used illegally from idle CPU!
rcu_scheduler_active = 1, debug_locks = 0
RCU used illegally from extended quiescent state!
no locks held by swapper/0/0.

stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc4-next-20160422 #1
Hardware name: Generic OMAP3-GP (Flattened Device Tree)
[<c010f55c>] (unwind_backtrace) from [<c010b64c>] (show_stack+0x10/0x14)
[<c010b64c>] (show_stack) from [<c047acbc>] (dump_stack+0xa8/0xe0)
[<c047acbc>] (dump_stack) from [<c012bc10>] (pwrdm_set_next_pwrst+0xf8/0x1cc)
[<c012bc10>] (pwrdm_set_next_pwrst) from [<c01269fc>] (omap3_enter_idle_bm+0x1b8/0x1e8)
[<c01269fc>] (omap3_enter_idle_bm) from [<c05fa0b8>] (cpuidle_enter_state+0x84/0x408)
[<c05fa0b8>] (cpuidle_enter_state) from [<c0182c1c>] (cpu_startup_entry+0x1c8/0x3f0)
[<c0182c1c>] (cpu_startup_entry) from [<c0b00c20>] (start_kernel+0x354/0x3cc)

------------------------------------------------------------------------

[<c010f55c>] (unwind_backtrace) from [<c010b64c>] (show_stack+0x10/0x14)
[<c010b64c>] (show_stack) from [<c047ac3c>] (dump_stack+0xa8/0xe0)
[<c047ac3c>] (dump_stack) from [<c012c340>] (_pwrdm_state_switch+0x188/0x32c)
[<c012c340>] (_pwrdm_state_switch) from [<c012c4f0>] (_pwrdm_post_transition_cb+0xc/0x14)
[<c012c4f0>] (_pwrdm_post_transition_cb) from [<c012ba74>] (pwrdm_for_each+0x30/0x5c)
[<c012ba74>] (pwrdm_for_each) from [<c012c72c>] (pwrdm_post_transition+0x24/0x30)
[<c012c72c>] (pwrdm_post_transition) from [<c012548c>] (omap_sram_idle+0xfc/0x240)
[<c012548c>] (omap_sram_idle) from [<c0126934>] (omap3_enter_idle_bm+0xf0/0x1e8)
[<c0126934>] (omap3_enter_idle_bm) from [<c05fa038>] (cpuidle_enter_state+0x84/0x408)
[<c05fa038>] (cpuidle_enter_state) from [<c0182b90>] (cpu_startup_entry+0x1c8/0x3f0)
[<c0182b90>] (cpu_startup_entry) from [<c0b00c20>] (start_kernel+0x354/0x3cc)

------------------------------------------------------------------------

These are caused by event tracing from the idle loop, and they were
exposed by commit 293e2421fe ("rcu: Remove superfluous versions of
rcu_read_lock_sched_held()"), which suppressed some false negatives.
The current commit therefore adds the _rcuidle suffix to make RCU aware
of this implicit use of RCU by event tracing, thus preventing both splats.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Tony Lindgren <tony@atomide.com>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: <linux-omap@vger.kernel.org>
Cc: <linux-arm-kernel@lists.infradead.org>
2016-04-29 13:29:02 -07:00
..
boot ARM: DT changes, part 2 2016-03-24 19:01:38 -07:00
common Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
configs ARM: SoC defconfig updates for v4.6 2016-03-20 15:32:14 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-03-17 11:22:54 -07:00
firmware
include arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
kernel arch, ftrace: for KASAN put hard/soft IRQ entries into separate sections 2016-03-25 16:37:42 -07:00
kvm KVM: arm/arm64: disable preemption when calling smp_call_function_many 2016-03-21 10:45:22 +01:00
lib
mach-alpine ARM: alpine: select the Alpine MSI controller driver 2016-02-26 22:57:22 +01:00
mach-artpec
mach-asm9260
mach-at91
mach-axxia
mach-bcm
mach-berlin
mach-clps711x
mach-cns3xxx ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-davinci ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-digicolor
mach-dove ARM: orion: only select I2C_BOARDINFO when using I2C 2016-02-25 15:37:16 +01:00
mach-ebsa110
mach-efm32
mach-ep93xx
mach-exynos ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-footbridge
mach-gemini
mach-highbank
mach-hisi
mach-imx ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-integrator
mach-iop13xx
mach-iop32x
mach-iop33x
mach-ixp4xx This is the bulk of GPIO changes for kernel v4.6: 2016-03-17 21:05:32 -07:00
mach-keystone ARM: DT updates for v4.6 2016-03-20 15:15:48 -07:00
mach-ks8695 ARM: SoC non-urgent fixes for v4.6 2016-03-20 14:26:57 -07:00
mach-lpc18xx
mach-lpc32xx ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-mediatek ARM: DT updates for v4.6 2016-03-20 15:15:48 -07:00
mach-meson
mach-mmp
mach-moxart
mach-mv78xx0 ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-mvebu The clk changes for this release cycle are mostly dominated by 2016-03-23 06:06:45 -07:00
mach-mxs
mach-netx ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-nomadik
mach-nspire ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-omap1 ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-omap2 arm: Use _rcuidle tracepoint to allow use from idle 2016-04-29 13:29:02 -07:00
mach-orion5x ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-picoxcell
mach-prima2 ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-pxa ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-qcom
mach-realview
mach-rockchip
mach-rpc
mach-s3c24xx ARM: SoC 64-bit changes for v4.6 2016-03-20 15:08:45 -07:00
mach-s3c64xx ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mach-s5pv210
mach-sa1100 Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
mach-shmobile The clk changes for this release cycle are mostly dominated by 2016-03-23 06:06:45 -07:00
mach-socfpga ARM: SoC non-urgent fixes for v4.6 2016-03-20 14:26:57 -07:00
mach-spear
mach-sti
mach-stm32
mach-sunxi
mach-tango
mach-tegra Here's another round of updates for -next: 2016-03-01 17:03:27 -05:00
mach-u300
mach-uniphier ARM: uniphier: rework SMP code to support new System Bus binding 2016-03-18 17:36:37 +01:00
mach-ux500 ARM: SoC cleanups for v4.6 2016-03-20 14:37:22 -07:00
mach-versatile
mach-vexpress
mach-vt8500
mach-w90x900 Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
mach-zx
mach-zynq ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
mm Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
net
nwfpe
oprofile
plat-iop
plat-omap
plat-orion Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm 2016-03-19 16:31:54 -07:00
plat-pxa ARM: pxa: add the number of DMA requestor lines 2016-02-26 22:57:05 +01:00
plat-samsung MTD updates for v4.6 2016-03-24 19:57:15 -07:00
plat-versatile
probes
tools
vdso
vfp
xen
Kconfig ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00
Kconfig-nommu
Kconfig.debug
Makefile ARM: SoC platform updates for v4.6 2016-03-20 14:57:08 -07:00