ARCv2: SMP: Emulate IPI to self using software triggered interrupt
ARConnect/MCIP Inter-Core-Interrupt module can't send interrupt to local core. So use core intc capability to trigger software interrupt to self, using an unsued IRQ #21. This showed up as csd deadlock with LTP trace_sched on a dual core system. This test acts as scheduler fuzzer, triggering all sorts of schedulting activity. Trouble starts with IPI to self, which doesn't get delivered (effectively lost due to H/w capability), but the msg intended to be sent remain enqueued in per-cpu @ipi_data. All subsequent IPIs to this core from other cores get elided due to the IPI coalescing optimization in ipi_send_msg_one() where a pending msg implies an IPI already sent and assumes other core is yet to ack it. After the elided IPI, other core simply goes into csd_lock_wait() but never comes out as this core never sees the interrupt. Fixes STAR 9001008624 Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> [4.2] Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Родитель
3e5177c191
Коммит
bb143f814e
|
@ -22,6 +22,7 @@
|
|||
#define AUX_IRQ_CTRL 0x00E
|
||||
#define AUX_IRQ_ACT 0x043 /* Active Intr across all levels */
|
||||
#define AUX_IRQ_LVL_PEND 0x200 /* Pending Intr across all levels */
|
||||
#define AUX_IRQ_HINT 0x201 /* For generating Soft Interrupts */
|
||||
#define AUX_IRQ_PRIORITY 0x206
|
||||
#define ICAUSE 0x40a
|
||||
#define AUX_IRQ_SELECT 0x40b
|
||||
|
@ -115,6 +116,16 @@ static inline int arch_irqs_disabled(void)
|
|||
return arch_irqs_disabled_flags(arch_local_save_flags());
|
||||
}
|
||||
|
||||
static inline void arc_softirq_trigger(int irq)
|
||||
{
|
||||
write_aux_reg(AUX_IRQ_HINT, irq);
|
||||
}
|
||||
|
||||
static inline void arc_softirq_clear(int irq)
|
||||
{
|
||||
write_aux_reg(AUX_IRQ_HINT, 0);
|
||||
}
|
||||
|
||||
#else
|
||||
|
||||
.macro IRQ_DISABLE scratch
|
||||
|
|
|
@ -45,11 +45,12 @@ VECTOR reserved ; Reserved slots
|
|||
VECTOR handle_interrupt ; (16) Timer0
|
||||
VECTOR handle_interrupt ; unused (Timer1)
|
||||
VECTOR handle_interrupt ; unused (WDT)
|
||||
VECTOR handle_interrupt ; (19) ICI (inter core interrupt)
|
||||
VECTOR handle_interrupt
|
||||
VECTOR handle_interrupt
|
||||
VECTOR handle_interrupt
|
||||
VECTOR handle_interrupt ; (23) End of fixed IRQs
|
||||
VECTOR handle_interrupt ; (19) Inter core Interrupt (IPI)
|
||||
VECTOR handle_interrupt ; (20) perf Interrupt
|
||||
VECTOR handle_interrupt ; (21) Software Triggered Intr (Self IPI)
|
||||
VECTOR handle_interrupt ; unused
|
||||
VECTOR handle_interrupt ; (23) unused
|
||||
# End of fixed IRQs
|
||||
|
||||
.rept CONFIG_ARC_NUMBER_OF_INTERRUPTS - 8
|
||||
VECTOR handle_interrupt
|
||||
|
|
|
@ -11,9 +11,12 @@
|
|||
#include <linux/smp.h>
|
||||
#include <linux/irq.h>
|
||||
#include <linux/spinlock.h>
|
||||
#include <asm/irqflags-arcv2.h>
|
||||
#include <asm/mcip.h>
|
||||
#include <asm/setup.h>
|
||||
|
||||
#define SOFTIRQ_IRQ 21
|
||||
|
||||
static char smp_cpuinfo_buf[128];
|
||||
static int idu_detected;
|
||||
|
||||
|
@ -22,6 +25,7 @@ static DEFINE_RAW_SPINLOCK(mcip_lock);
|
|||
static void mcip_setup_per_cpu(int cpu)
|
||||
{
|
||||
smp_ipi_irq_setup(cpu, IPI_IRQ);
|
||||
smp_ipi_irq_setup(cpu, SOFTIRQ_IRQ);
|
||||
}
|
||||
|
||||
static void mcip_ipi_send(int cpu)
|
||||
|
@ -29,6 +33,12 @@ static void mcip_ipi_send(int cpu)
|
|||
unsigned long flags;
|
||||
int ipi_was_pending;
|
||||
|
||||
/* ARConnect can only send IPI to others */
|
||||
if (unlikely(cpu == raw_smp_processor_id())) {
|
||||
arc_softirq_trigger(SOFTIRQ_IRQ);
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* NOTE: We must spin here if the other cpu hasn't yet
|
||||
* serviced a previous message. This can burn lots
|
||||
|
@ -63,6 +73,11 @@ static void mcip_ipi_clear(int irq)
|
|||
unsigned long flags;
|
||||
unsigned int __maybe_unused copy;
|
||||
|
||||
if (unlikely(irq == SOFTIRQ_IRQ)) {
|
||||
arc_softirq_clear(irq);
|
||||
return;
|
||||
}
|
||||
|
||||
raw_spin_lock_irqsave(&mcip_lock, flags);
|
||||
|
||||
/* Who sent the IPI */
|
||||
|
|
Загрузка…
Ссылка в новой задаче