Re: [PATCH v2 2/3] irqchip/sifive-plic: Setup cpuhp once after boot CPU handler is present

On Fri, May 22, 2020 at 3:36 AM Palmer Dabbelt palmer@dabbelt.com wrote:

On Mon, 18 May 2020 02:14:40 PDT (-0700), Anup Patel wrote:

...

For multiple PLIC instances, the plic_init() is called once for each PLIC instance. Due to this we have two issues:

1. cpuhp_setup_state() is called multiple times
2. plic_starting_cpu() can crash for boot CPU if cpuhp_setup_state() is called before boot CPU PLIC handler is available.

This patch fixes both above issues.

Fixes: f1ad1133b18f ("irqchip/sifive-plic: Add support for multiple PLICs") Cc: stable@vger.kernel.org Signed-off-by: Anup Patel anup.patel@wdc.com

---

drivers/irqchip/irq-sifive-plic.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c index 9f7f8ce88c00..6c54abf5cc5e 100644 --- a/drivers/irqchip/irq-sifive-plic.c +++ b/drivers/irqchip/irq-sifive-plic.c @@ -76,6 +76,7 @@ struct plic_handler { void __iomem *enable_base; struct plic_priv *priv; }; +static bool plic_cpuhp_setup_done; static DEFINE_PER_CPU(struct plic_handler, plic_handlers);

static inline void plic_toggle(struct plic_handler *handler, @@ -285,6 +286,7 @@ static int __init plic_init(struct device_node *node, int error = 0, nr_contexts, nr_handlers = 0, i; u32 nr_irqs; struct plic_priv *priv;

• struct plic_handler *handler;
  
  priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  if (!priv)
  

@@ -313,7 +315,6 @@ static int __init plic_init(struct device_node *node,

  for (i = 0; i < nr_contexts; i++) {
          struct of_phandle_args parent;

•         struct plic_handler *handler;
          irq_hw_number_t hwirq;
          int cpu, hartid;
  
  

@@ -367,9 +368,18 @@ static int __init plic_init(struct device_node *node, nr_handlers++; }

• cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
  

• /*
  

•  * We can have multiple PLIC instances so setup cpuhp state only
  

•  * when context handler for current/boot CPU is present.
  

•  */
  

• handler = this_cpu_ptr(&plic_handlers);
  

• if (handler->present && !plic_cpuhp_setup_done) {
  

•         cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
                            "irqchip/sifive/plic:starting",
                            plic_starting_cpu, plic_dying_cpu);
  

•         plic_cpuhp_setup_done = true;
  

So presumably something else is preventing multiple plic_init() calls from executing at the same time? Assuming that's the case

AFAIK, interrupt controller and timer probing happens sequentially on boot CPU before all secondary CPUs are brought-up.

Reviewed-by: Palmer Dabbelt palmerdabbelt@google.com Acked-by: Palmer Dabbelt palmerdabbelt@google.com

...

• }
  

• pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
          nr_irqs, nr_handlers, nr_contexts);
  set_handle_irq(plic_handle_irq);
  

Thanks, Anup