Provide the same horrible semantics provided by smp_call_function_single_async(), doing so allows skiping a bunch of atomic ops.
API wise this is horrible crap as it relies on external serialization. Signed-off-by: Peter Zijlstra (Intel) <[email protected]> --- include/linux/irq_work.h | 3 ++- kernel/irq_work.c | 21 ++++++++++++++++++++- 2 files changed, 22 insertions(+), 2 deletions(-) --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h @@ -19,7 +19,7 @@ struct irq_work { }; #define __IRQ_WORK_INIT(_func, _flags) (struct irq_work){ \ - .node = { .u_flags = (_flags), }, \ + .node = { .u_flags = CSD_TYPE_IRQ_WORK | (_flags), }, \ .func = (_func), \ } @@ -68,6 +68,7 @@ static inline bool irq_work_needs_cpu(vo #ifdef CONFIG_SMP extern int irq_work_queue_remote(int cpu, struct irq_work *work); +extern int irq_work_queue_remote_static(int cpu, struct irq_work *work); extern void irq_work_single(void *arg); #endif --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -29,7 +29,7 @@ static bool irq_work_claim(struct irq_wo { int oflags; - oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->node.a_flags); + oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->node.a_flags); /* * If the work is already pending, no need to raise the IPI. * The pairing smp_mb() in irq_work_single() makes sure @@ -63,6 +63,9 @@ void irq_work_single(void *arg) work->func(work); lockdep_irq_work_exit(flags); + if (!(flags & IRQ_WORK_BUSY)) + return; + /* * Clear the BUSY bit, if set, and return to the free state if no-one * else claimed it meanwhile. @@ -108,6 +111,22 @@ int irq_work_queue_remote(int cpu, struc return 0; } + +int irq_work_queue_remote_static(int cpu, struct irq_work *work) +{ + /* + * Ensures preemption is disabled in the caller. + */ + WARN_ON_ONCE(cpu == smp_processor_id()); + + if (work->node.u_flags & IRQ_WORK_PENDING) + return -EBUSY; + + work->node.u_flags |= IRQ_WORK_PENDING; + __smp_call_single_queue(cpu, &work->node.llist); + + return 0; +} #endif /* CONFIG_SMP */
