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authorThomas Huth <thuth@redhat.com>2015-07-17 12:46:58 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-01 12:07:30 +0200
commit2ba90c0e0638dba68ffe6e78b135729e41a4540a (patch)
treea828187b692fea939a18e8dbfe36df41287336bf
parent36e5789bc706a67a0281a14b3888b3f5d0f723e0 (diff)
downloadlinux-linaro-stable-2ba90c0e0638dba68ffe6e78b135729e41a4540a.tar.gz
powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers
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@redhat.com> Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/powerpc/include/asm/rtas.h1
-rw-r--r--arch/powerpc/kernel/rtas.c17
-rw-r--r--arch/powerpc/platforms/pseries/ras.c3
3 files changed, 20 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 34fd70488d83..c5d5cb36f6c6 100644
--- 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);
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 52add6f3e201..f956a2f84a15 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 c4dfccd3a3d9..2338e6e98483 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -187,7 +187,8 @@ 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 */