----- Original Message -----
> The EPOW interrupt handler uses rtas_get_sensor(), which in turn
> uses rtas_busy_delay() to wait for RTAS becoming ready in case it
> is necessary. But rtas_busy_delay() is annotated with might_sleep()
> and thus may not be used by interrupts handlers like the EPOW handler!
> This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
> enabled:
>
> BUG: sleeping function called from invalid context at
> arch/powerpc/kernel/rtas.c:496
> in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6
> Call Trace:
> [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable)
> [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180
> [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0
> [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0
> [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450
> [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300
> [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0
> [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260
> [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80
> [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200
> [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24
> [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110
> [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180
>
> Fix this issue by introducing a new rtas_get_sensor_fast() function
> that does not use rtas_busy_delay() - and thus can only be used for
> sensors that do not cause a BUSY condition (which should be the case
> for the sensor that is queried by the EPOW IRQ handler).
>
> Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
> ---
> arch/powerpc/include/asm/rtas.h | 1 +
> arch/powerpc/kernel/rtas.c | 17 +++++++++++++++++
> arch/powerpc/platforms/pseries/ras.c | 3 ++-
> 3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/rtas.h
> b/arch/powerpc/include/asm/rtas.h
> index 7a4ede1..b77ef36 100644
> --- a/arch/powerpc/include/asm/rtas.h
> +++ b/arch/powerpc/include/asm/rtas.h
> @@ -343,6 +343,7 @@ extern void rtas_power_off(void);
> extern void rtas_halt(void);
> extern void rtas_os_term(char *str);
> extern int rtas_get_sensor(int sensor, int index, int *state);
> +extern int rtas_get_sensor_fast(int sensor, int index, int *state);
> extern int rtas_get_power_level(int powerdomain, int *level);
> extern int rtas_set_power_level(int powerdomain, int level, int *setlevel);
> extern bool rtas_indicator_present(int token, int *maxindex);
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 7a488c1..caffb10 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -584,6 +584,23 @@ int rtas_get_sensor(int sensor, int index, int *state)
> }
> EXPORT_SYMBOL(rtas_get_sensor);
>
> +int rtas_get_sensor_fast(int sensor, int index, int *state)
> +{
> + int token = rtas_token("get-sensor-state");
> + int rc;
> +
> + if (token == RTAS_UNKNOWN_SERVICE)
> + return -ENOENT;
> +
> + rc = rtas_call(token, 2, 2, state, sensor, index);
> + WARN_ON(rc == RTAS_BUSY || (rc >= RTAS_EXTENDED_DELAY_MIN &&
> + rc <= RTAS_EXTENDED_DELAY_MAX));
> +
> + if (rc < 0)
> + return rtas_error_rc(rc);
> + return rc;
> +}
> +
> bool rtas_indicator_present(int token, int *maxindex)
> {
> int proplen, count, i;
> diff --git a/arch/powerpc/platforms/pseries/ras.c
> b/arch/powerpc/platforms/pseries/ras.c
> index 02e4a17..3b6647e 100644
> --- a/arch/powerpc/platforms/pseries/ras.c
> +++ b/arch/powerpc/platforms/pseries/ras.c
> @@ -189,7 +189,8 @@ static irqreturn_t ras_epow_interrupt(int irq, void
> *dev_id)
> int state;
> int critical;
>
> - status = rtas_get_sensor(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, &state);
> + status = rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX,
> + &state);
>
> if (state > 3)
> critical = 1; /* Time Critical */
> --
> 1.8.3.1
*ping*
Michael, do you think this patch is OK for fixing this problem?
Or shall I rather send a patch to simply revert 587f83e8dd50d instead?
Thomas
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