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    Subject[PATCH v2 1/2] riscv: Support irq_work via self IPIs
    Date
    Support for arch_irq_work_raise() and arch_irq_work_has_interrupt() was
    missing from riscv (a prerequisite for FULL_NOHZ).

    Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
    ---
    arch/riscv/include/asm/irq_work.h | 10 ++++++++++
    arch/riscv/kernel/smp.c | 15 +++++++++++++++
    2 files changed, 25 insertions(+)
    create mode 100644 arch/riscv/include/asm/irq_work.h

    diff --git a/arch/riscv/include/asm/irq_work.h b/arch/riscv/include/asm/irq_work.h
    new file mode 100644
    index 000000000000..d6c277992f76
    --- /dev/null
    +++ b/arch/riscv/include/asm/irq_work.h
    @@ -0,0 +1,10 @@
    +/* SPDX-License-Identifier: GPL-2.0 */
    +#ifndef _ASM_RISCV_IRQ_WORK_H
    +#define _ASM_RISCV_IRQ_WORK_H
    +
    +static inline bool arch_irq_work_has_interrupt(void)
    +{
    + return true;
    +}
    +extern void arch_irq_work_raise(void);
    +#endif /* _ASM_RISCV_IRQ_WORK_H */
    diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
    index b1d4f452f843..554b0fb47060 100644
    --- a/arch/riscv/kernel/smp.c
    +++ b/arch/riscv/kernel/smp.c
    @@ -16,6 +16,7 @@
    #include <linux/sched.h>
    #include <linux/seq_file.h>
    #include <linux/delay.h>
    +#include <linux/irq_work.h>

    #include <asm/clint.h>
    #include <asm/sbi.h>
    @@ -26,6 +27,7 @@ enum ipi_message_type {
    IPI_RESCHEDULE,
    IPI_CALL_FUNC,
    IPI_CPU_STOP,
    + IPI_IRQ_WORK,
    IPI_MAX
    };

    @@ -123,6 +125,13 @@ static inline void clear_ipi(void)
    clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
    }

    +#ifdef CONFIG_IRQ_WORK
    +void arch_irq_work_raise(void)
    +{
    + send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
    +}
    +#endif
    +
    void handle_IPI(struct pt_regs *regs)
    {
    struct pt_regs *old_regs = set_irq_regs(regs);
    @@ -158,6 +167,11 @@ void handle_IPI(struct pt_regs *regs)
    ipi_stop();
    }

    + if (ops & (1 << IPI_IRQ_WORK)) {
    + stats[IPI_IRQ_WORK]++;
    + irq_work_run();
    + }
    +
    BUG_ON((ops >> IPI_MAX) != 0);

    /* Order data access and bit testing. */
    @@ -173,6 +187,7 @@ static const char * const ipi_names[] = {
    [IPI_RESCHEDULE] = "Rescheduling interrupts",
    [IPI_CALL_FUNC] = "Function call interrupts",
    [IPI_CPU_STOP] = "CPU stop interrupts",
    + [IPI_IRQ_WORK] = "IRQ work interrupts",
    };

    void show_ipi_stats(struct seq_file *p, int prec)
    --
    2.27.0
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