linux/drivers/clk
Mike Tipton 54baf56eaa clk: Don't parent clks until the parent is fully registered
Before commit fc0c209c14 ("clk: Allow parents to be specified without
string names") child clks couldn't find their parent until the parent
clk was added to a list in __clk_core_init(). After that commit, child
clks can reference their parent clks directly via a clk_hw pointer, or
they can lookup that clk_hw pointer via DT if the parent clk is
registered with an OF clk provider.

The common clk framework treats hw->core being non-NULL as "the clk is
registered" per the logic within clk_core_fill_parent_index():

	parent = entry->hw->core;
	/*
	 * We have a direct reference but it isn't registered yet?
	 * Orphan it and let clk_reparent() update the orphan status
	 * when the parent is registered.
	 */
	if (!parent)

Therefore we need to be extra careful to not set hw->core until the clk
is fully registered with the clk framework. Otherwise we can get into a
situation where a child finds a parent clk and we move the child clk off
the orphan list when the parent isn't actually registered, wrecking our
enable accounting and breaking critical clks.

Consider the following scenario:

  CPU0                                     CPU1
  ----                                     ----
  struct clk_hw clkBad;
  struct clk_hw clkA;

  clkA.init.parent_hws = { &clkBad };

  clk_hw_register(&clkA)                   clk_hw_register(&clkBad)
   ...                                      __clk_register()
					     hw->core = core
					     ...
   __clk_register()
    __clk_core_init()
     clk_prepare_lock()
     __clk_init_parent()
      clk_core_get_parent_by_index()
       clk_core_fill_parent_index()
        if (entry->hw) {
	 parent = entry->hw->core;

At this point, 'parent' points to clkBad even though clkBad hasn't been
fully registered yet. Ouch! A similar problem can happen if a clk
controller registers orphan clks that are referenced in the DT node of
another clk controller.

Let's fix all this by only setting the hw->core pointer underneath the
clk prepare lock in __clk_core_init(). This way we know that
clk_core_fill_parent_index() can't see hw->core be non-NULL until the
clk is fully registered.

Fixes: fc0c209c14 ("clk: Allow parents to be specified without string names")
Signed-off-by: Mike Tipton <quic_mdtipton@quicinc.com>
Link: https://lore.kernel.org/r/20211109043438.4639-1-quic_mdtipton@quicinc.com
[sboyd@kernel.org: Reword commit text, update comment]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2021-12-07 19:20:35 -08:00
..
actions clk/actions/owl-factor.c: remove superfluous headers 2021-11-02 14:28:29 -07:00
analogbits Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
at91 clk: at91: sama7g5: set low limit for mck0 at 32KHz 2021-10-26 18:27:43 -07:00
axis
axs10x
baikal-t1 clk: baikal-t1: Mark Ethernet PLL as critical 2020-10-13 19:48:34 -07:00
bcm clk: bcm2835: Switch to clk_divider.determine_rate 2021-08-05 17:36:10 -07:00
berlin
davinci This pull request contains zero diff to the core framework. It is a collection 2020-10-22 12:53:28 -07:00
h8300
hisilicon clk: hisilicon: hi3559a: select RESET_HISI 2021-07-26 17:23:40 -07:00
imgtec treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
imx clk: imx: use module_platform_driver 2021-12-02 17:57:24 -08:00
ingenic Devicetree fixes for v5.16, take 1: 2021-11-14 11:11:51 -08:00
keystone clk: keystone: syscon-clk: Add support for AM64 specific epwm-tbclk 2021-06-22 14:18:26 -07:00
loongson1
mediatek clk:mediatek: remove duplicate include in clk-mt8195-imp_iic_wrap.c 2021-11-02 15:27:21 -07:00
meson clk: meson: meson8b: Make the video clock trees mutable 2021-09-23 11:46:38 +02:00
microchip
mmp clk: mmp2: fix build without CONFIG_PM 2021-01-12 12:10:55 -08:00
mstar clk: mstar: msc313-mpll: Fix format specifier 2021-02-16 12:52:28 -08:00
mvebu clk: mvebu: ap-cpu-clk: Fix a memory leak in error handling paths 2021-09-14 18:25:16 -07:00
mxs
nxp
pistachio clk: pistachio: Make it selectable for generic MIPS kernel 2021-08-12 16:01:49 +02:00
pxa clk: pxa: Constify static struct clk_ops 2020-10-13 19:49:11 -07:00
qcom clk: qcom: sm6125-gcc: Swap ops of ice and apps on sdcc1 2021-12-06 14:40:38 -08:00
ralink clk: ralink: avoid to set 'CLK_IS_CRITICAL' flag for gates 2021-08-28 22:24:06 -07:00
renesas clk: renesas: r8a779[56]x: Add MLP clocks 2021-10-15 09:46:14 +02:00
rockchip clk: rockchip: drop module parts from rk3399 and rk3568 drivers 2021-11-02 17:59:00 -07:00
samsung clk: samsung: describe drivers in Kconfig 2021-10-18 10:12:48 +02:00
sifive clk: sifive: Fix kernel-doc 2021-06-01 23:39:15 -07:00
socfpga clk: socfpga: agilex: fix duplicate s2f_user0_clk 2021-09-24 16:03:08 -07:00
spear clk: spear: Move prototype to accessible header 2021-02-11 11:56:06 -08:00
sprd This time around we have 4 lines of diff in the core framework, removing a 2020-06-10 11:42:19 -07:00
st clk: st: clkgen-fsyn: embed soc clock outputs within compatible data 2021-06-27 19:53:40 -07:00
sunxi clk: sunxi: sun8i-apb0: Make use of the helper function devm_platform_ioremap_resource() 2021-09-13 09:03:24 +02:00
sunxi-ng clk: sunxi-ng: ccu-sun9i-a80-usb: Make use of the helper function devm_platform_ioremap_resource() 2021-09-13 09:03:23 +02:00
tegra Nothing changed in the clk framework core this time around. We did get 2021-09-02 14:17:24 -07:00
ti clk: ti: am43xx: Add clkctrl data for am43xx ADC1 2021-10-20 17:06:20 +01:00
uniphier clk: uniphier: Add SoC-glue clock source selector support for Pro4 2021-11-02 14:34:51 -07:00
ux500 clk: ux500: Add driver for the reset portions of PRCC 2021-10-26 18:06:05 -07:00
versatile clk: versatile: clk-icst: use after free on error path 2021-12-07 12:25:29 -08:00
x86 clk: x86: Rename clk-lpt to more specific clk-lpss-atom 2021-07-27 14:03:47 -07:00
xilinx clk: xilinx: move xlnx_vcu clock driver from soc 2021-02-08 18:31:25 -08:00
zynq clk: zynq: clkc: Remove various instances of an unused variable 'clk' 2021-02-11 11:56:07 -08:00
zynqmp Merge branches 'clk-kirkwood', 'clk-imx', 'clk-doc', 'clk-zynq' and 'clk-ralink' into clk-next 2021-09-01 15:27:07 -07:00
clk-asm9260.c clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo 2020-04-13 12:20:06 -07:00
clk-aspeed.c
clk-aspeed.h
clk-ast2600.c clk/ast2600: Fix soc revision for AHB 2021-11-03 19:42:35 -07:00
clk-axi-clkgen.c clk: axi-clkgen: use devm_platform_ioremap_resource() short-hand 2021-02-08 18:13:13 -08:00
clk-axm5516.c
clk-bd718x7.c clk: bd718xx: Drop BD70528 support 2021-06-27 18:42:45 -07:00
clk-bm1880.c
clk-bulk.c
clk-cdce706.c Replace HTTP links with HTTPS ones: Common CLK framework 2020-07-10 17:15:34 -07:00
clk-cdce925.c
clk-clps711x.c
clk-composite.c clk: composite: Fix 'switching' to same clock 2021-11-03 17:49:54 -07:00
clk-conf.c
clk-cs2000-cp.c
clk-devres.c clk: fix leak on devm_clk_bulk_get_all() unwind 2021-07-31 00:53:38 -07:00
clk-divider.c clk: divider: Implement and wire up .determine_rate by default 2021-08-05 17:35:58 -07:00
clk-fixed-factor.c clk: fixed: fix double free in resource managed fixed-factor clock 2021-04-07 16:01:25 -07:00
clk-fixed-mmio.c clk: clk-fixed-mmio: Demote obvious kernel-doc abuse 2021-02-11 11:56:05 -08:00
clk-fixed-rate.c clk: fixed: add missing kerneldoc 2020-09-22 12:44:14 -07:00
clk-fractional-divider.c clk: fractional-divider: Document the arithmetics used behind the code 2021-08-12 12:42:00 -07:00
clk-fractional-divider.h clk: fractional-divider: Hide clk_fractional_divider_ops from wide audience 2021-08-12 12:42:00 -07:00
clk-fsl-flexspi.c clk: fsl-flexspi: new driver 2020-12-07 16:56:41 -08:00
clk-fsl-sai.c clk: fsl-sai: use devm_clk_hw_register_composite_pdata() 2020-12-07 14:06:16 -08:00
clk-gate.c treewide: Remove uninitialized_var() usage 2020-07-16 12:35:15 -07:00
clk-gemini.c
clk-gpio.c Replace HTTP links with HTTPS ones: Common CLK framework 2020-07-10 17:15:34 -07:00
clk-hi655x.c
clk-highbank.c
clk-hsdk-pll.c CLK: HSDK: CGU: add support for 148.5MHz clock 2020-05-28 21:06:39 -07:00
clk-k210.c clk: k210: Fix k210_clk_set_parent() 2021-06-30 11:34:36 -07:00
clk-lmk04832.c clk: lmk04832: drop redundant fallthrough statements 2021-07-27 11:52:30 -07:00
clk-lochnagar.c
clk-max9485.c
clk-max77686.c
clk-milbeaut.c
clk-moxart.c
clk-multiplier.c
clk-mux.c clk: mux: provide devm_clk_hw_register_mux() 2021-04-07 11:05:44 -07:00
clk-nomadik.c
clk-npcm7xx.c clk: clk-npcm7xx: Remove unused static const tables 'npcm7xx_gates' and 'npcm7xx_divs_fx' 2021-02-11 11:56:05 -08:00
clk-nspire.c
clk-oxnas.c
clk-palmas.c clk: palmas: Add a missing SPDX license header 2021-08-05 17:34:30 -07:00
clk-plldig.c clk: ls1028a: fix a dereference of pointer 'parent' before a null check 2020-02-03 23:03:49 -08:00
clk-pwm.c clk: pwm: drop of_match_ptr from of_device_id table 2020-12-10 12:24:18 -08:00
clk-qoriq.c clk: qoriq: use macros to generate pll_mask 2021-02-14 13:02:01 -08:00
clk-rk808.c
clk-s2mps11.c clk: s2mps11: Fix a resource leak in error handling paths in the probe function 2020-12-19 15:53:31 -08:00
clk-scmi.c clk: scmi: Port driver to the new scmi_clk_proto_ops interface 2021-03-30 16:34:37 +01:00
clk-scpi.c clk: scpi: mark scpi_clk_match as maybe unused 2020-12-10 12:24:40 -08:00
clk-si514.c
clk-si544.c
clk-si570.c clk: si570: Skip NVM to RAM recall operation if an optional property is set 2021-02-11 12:13:50 -08:00
clk-si5341.c clk: si5341: Add sysfs properties to allow checking/resetting device faults 2021-06-27 19:58:15 -07:00
clk-si5351.c clk: si5351: Update datasheet references 2021-11-02 14:29:17 -07:00
clk-si5351.h clk: si5351: Update datasheet references 2021-11-02 14:29:17 -07:00
clk-sparx5.c clk: sparx5: Add Sparx5 SoC DPLL clock driver 2020-07-28 18:17:56 -07:00
clk-stm32f4.c Nothing changed in the clk framework core this time around. We did get 2021-09-02 14:17:24 -07:00
clk-stm32h7.c clk: stm32h7: Switch to clk_divider.determine_rate 2021-08-05 17:36:10 -07:00
clk-stm32mp1.c clk: stm32mp1: Switch to clk_divider.determine_rate 2021-08-05 17:36:10 -07:00
clk-twl6040.c
clk-versaclock5.c clk: vc5: Use i2c .probe_new 2021-11-02 14:28:51 -07:00
clk-vt8500.c
clk-wm831x.c
clk-xgene.c clk: clk-xgene: Add description for 'mask' and fix formatting for 'flags' 2021-02-11 11:56:06 -08:00
clk.c clk: Don't parent clks until the parent is fully registered 2021-12-07 19:20:35 -08:00
clk.h
clkdev.c clkdev: remove unused clkdev_alloc() interfaces 2021-06-08 17:00:09 +02:00
Kconfig clk: pistachio: Make it selectable for generic MIPS kernel 2021-08-12 16:01:49 +02:00
Makefile clk: pistachio: Make it selectable for generic MIPS kernel 2021-08-12 16:01:49 +02:00