Re: [RFC 2/5] serial: core: Add framework to allow NMI aware serial drivers
From: Daniel Thompson <hidden>
Date: 2020-08-17 14:28:54
Also in:
linux-serial, lkml
On Mon, Aug 17, 2020 at 05:57:03PM +0530, Sumit Garg wrote:
quoted hunk ↗ jump to hunk
On Fri, 14 Aug 2020 at 19:43, Daniel Thompson [off-list ref] wrote:quoted
On Fri, Aug 14, 2020 at 04:47:11PM +0530, Sumit Garg wrote: Does it look better if you create a new type to map the two structures together. Alternatively are there enough existing use-cases to want to extend irq_work_queue() with irq_work_schedule() or something similar?Thanks for your suggestion, irq_work_schedule() looked even better without any overhead, see below:diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h index 3082378..1eade89 100644 --- a/include/linux/irq_work.h +++ b/include/linux/irq_work.h@@ -3,6 +3,7 @@ #define _LINUX_IRQ_WORK_H #include <linux/smp_types.h> +#include <linux/workqueue.h> /* * An entry can be in one of four states:@@ -24,6 +25,11 @@ struct irq_work { void (*func)(struct irq_work *); }; +struct irq_work_schedule { + struct irq_work work; + struct work_struct *sched_work; +}; + static inline void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *)) { {@@ -39,6 +45,7 @@ void init_irq_work(struct irq_work *work, void(*func)(struct irq_work *)) bool irq_work_queue(struct irq_work *work); bool irq_work_queue_on(struct irq_work *work, int cpu); +bool irq_work_schedule(struct work_struct *sched_work); void irq_work_tick(void); void irq_work_sync(struct irq_work *work);diff --git a/kernel/irq_work.c b/kernel/irq_work.c index eca8396..3880316 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c@@ -24,6 +24,8 @@ static DEFINE_PER_CPU(struct llist_head, raised_list); static DEFINE_PER_CPU(struct llist_head, lazy_list); +static struct irq_work_schedule irq_work_sched; + /* * Claim the entry so that no one else will poke at it. */@@ -79,6 +81,25 @@ bool irq_work_queue(struct irq_work *work) } EXPORT_SYMBOL_GPL(irq_work_queue); +static void irq_work_schedule_fn(struct irq_work *work) +{ + struct irq_work_schedule *irq_work_sched = + container_of(work, struct irq_work_schedule, work); + + if (irq_work_sched->sched_work) + schedule_work(irq_work_sched->sched_work); +} + +/* Schedule work via irq work queue */ +bool irq_work_schedule(struct work_struct *sched_work) +{ + init_irq_work(&irq_work_sched.work, irq_work_schedule_fn); + irq_work_sched.sched_work = sched_work; + + return irq_work_queue(&irq_work_sched.work); +} +EXPORT_SYMBOL_GPL(irq_work_schedule); +
This is irredeemably broken. Even if we didn't care about dropping events (which we do) then when you overwrite irq_work_sched with a copy of another work_struct, either of which could currently be enqueued somewhere, then you will cause some very nasty corruption. Daniel. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel