This is a note to let you know that I've just added the patch titled powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-rtas-introduce-rtas_get_sensor_fast-for-irq-handlers.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 1c2cb594441d02815d304cccec9742ff5c707495 Mon Sep 17 00:00:00 2001 From: Thomas Huth <thuth@xxxxxxxxxx> Date: Fri, 17 Jul 2015 12:46:58 +0200 Subject: powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers From: Thomas Huth <thuth@xxxxxxxxxx> commit 1c2cb594441d02815d304cccec9742ff5c707495 upstream. 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 - known as "fast" sensors. The EPOW sensor is defined to be "fast" in sPAPR - mpe. Fixes: 587f83e8dd50 ("powerpc/pseries: Use rtas_get_sensor in RAS code") Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx> Reviewed-by: Nathan Fontenot <nfont@xxxxxxxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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(-) --- a/arch/powerpc/include/asm/rtas.h +++ b/arch/powerpc/include/asm/rtas.h @@ -255,6 +255,7 @@ 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); --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -584,6 +584,23 @@ int rtas_get_sensor(int sensor, int inde } 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; --- a/arch/powerpc/platforms/pseries/ras.c +++ b/arch/powerpc/platforms/pseries/ras.c @@ -187,7 +187,8 @@ static irqreturn_t ras_epow_interrupt(in 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 */ Patches currently in stable-queue which might be from thuth@xxxxxxxxxx are queue-3.10/powerpc-rtas-introduce-rtas_get_sensor_fast-for-irq-handlers.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html