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| Filename | Latest commit message | Latest commit date |
|---|---|---|
788d9e9a41
commit a37eecb705f33726f1fb7cd2a67e514a15dfe693 upstream.
If a device uses MCP23xxx IO expander to receive IRQs, the following
bug can happen:
BUG: sleeping function called from invalid context
at kernel/locking/mutex.c:283
in_atomic(): 1, irqs_disabled(): 1, non_block: 0, ...
preempt_count: 1, expected: 0
...
Call Trace:
...
__might_resched+0x104/0x10e
__might_sleep+0x3e/0x62
mutex_lock+0x20/0x4c
regmap_lock_mutex+0x10/0x18
regmap_update_bits_base+0x2c/0x66
mcp23s08_irq_set_type+0x1ae/0x1d6
__irq_set_trigger+0x56/0x172
__setup_irq+0x1e6/0x646
request_threaded_irq+0xb6/0x160
...
We observed the problem while experimenting with a touchscreen driver which
used MCP23017 IO expander (I2C).
The regmap in the pinctrl-mcp23s08 driver uses a mutex for protection from
concurrent accesses, which is the default for regmaps without .fast_io,
.disable_locking, etc.
mcp23s08_irq_set_type() calls regmap_update_bits_base(), and the latter
locks the mutex.
However, __setup_irq() locks desc->lock spinlock before calling these
functions. As a result, the system tries to lock the mutex whole holding
the spinlock.
It seems, the internal regmap locks are not needed in this driver at all.
mcp->lock seems to protect the regmap from concurrent accesses already,
except, probably, in mcp_pinconf_get/set.
mcp23s08_irq_set_type() and mcp23s08_irq_mask/unmask() are called under
chip_bus_lock(), which calls mcp23s08_irq_bus_lock(). The latter takes
mcp->lock and enables regmap caching, so that the potentially slow I2C
accesses are deferred until chip_bus_unlock().
The accesses to the regmap from mcp23s08_probe_one() do not need additional
locking.
In all remaining places where the regmap is accessed, except
mcp_pinconf_get/set(), the driver already takes mcp->lock.
This patch adds locking in mcp_pinconf_get/set() and disables internal
locking in the regmap config. Among other things, it fixes the sleeping
in atomic context described above.
Fixes:
|
||
| .. | ||
| actions | ||
| aspeed | ||
| bcm | ||
| berlin | ||
| cirrus | ||
| freescale | ||
| intel | ||
| mediatek | ||
| meson | ||
| mvebu | ||
| nomadik | ||
| nuvoton | ||
| pxa | ||
| qcom | ||
| samsung | ||
| sh-pfc | ||
| sirf | ||
| spear | ||
| sprd | ||
| stm32 | ||
| sunxi | ||
| tegra | ||
| ti | ||
| uniphier | ||
| vt8500 | ||
| zte | ||
| core.c | ||
| core.h | ||
| devicetree.c | ||
| devicetree.h | ||
| Kconfig | ||
| Makefile | ||
| pinconf-generic.c | ||
| pinconf.c | ||
| pinconf.h | ||
| pinctrl-amd.c | ||
| pinctrl-amd.h | ||
| pinctrl-artpec6.c | ||
| pinctrl-as3722.c | ||
| pinctrl-at91-pio4.c | ||
| pinctrl-at91.c | ||
| pinctrl-at91.h | ||
| pinctrl-axp209.c | ||
| pinctrl-bm1880.c | ||
| pinctrl-coh901.c | ||
| pinctrl-coh901.h | ||
| pinctrl-da850-pupd.c | ||
| pinctrl-digicolor.c | ||
| pinctrl-falcon.c | ||
| pinctrl-gemini.c | ||
| pinctrl-ingenic.c | ||
| pinctrl-lantiq.c | ||
| pinctrl-lantiq.h | ||
| pinctrl-lpc18xx.c | ||
| pinctrl-max77620.c | ||
| pinctrl-mcp23s08.c | ||
| pinctrl-ocelot.c | ||
| pinctrl-oxnas.c | ||
| pinctrl-palmas.c | ||
| pinctrl-pic32.c | ||
| pinctrl-pic32.h | ||
| pinctrl-pistachio.c | ||
| pinctrl-rk805.c | ||
| pinctrl-rockchip.c | ||
| pinctrl-rza1.c | ||
| pinctrl-rza2.c | ||
| pinctrl-rzn1.c | ||
| pinctrl-single.c | ||
| pinctrl-st.c | ||
| pinctrl-stmfx.c | ||
| pinctrl-sx150x.c | ||
| pinctrl-tb10x.c | ||
| pinctrl-u300.c | ||
| pinctrl-utils.c | ||
| pinctrl-utils.h | ||
| pinctrl-xway.c | ||
| pinctrl-zynq.c | ||
| pinmux.c | ||
| pinmux.h | ||