Messages in this thread Patch in this message | | | From | Grygorii Strashko <> | Subject | [v4.1.10-rt10][PATCH 1/2] genirq: introduce new generic_handle_irq_rt_wa() api | Date | Mon, 2 Nov 2015 21:30:25 +0200 |
| |
Now in kernel below code pattern is used by many drivers: static irqreturn_t driver_xx_hw_irq_handler(int irq, void *arg) { <read IRQ status register> <perform HW specific operations>
for (<each set bit in IRQ status register>) { <get Linux IRQ number> generic_handle_irq(<Linux IRQ number>); |- handle_simple_irq() |-or- handle_level_irq() |-or- handle_edge_irq() |-handle_irq_event() |-handle_irq_event_percpu() === "WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150 handle_irq_event_percpu+0x14c/0x174() irq 460 handler irq_default_primary_handler+0x0/0x14 enabled interrupts" === } }
On -RT above code will generate warnings, because driver_xx_hw_irq_handler() will be forced threaded (by default) and, as result, generic_handle_irq() will be called with IRQs enabled. To W/A this issue generic_handle_irq() can be surrounded by raw_spin_lock_irqsave/irqrestore(wa_lock).
Instead of spreading this W/A directly in many drivers this patch introduces -RT specific version of generic_handle_irq() API - generic_handle_irq_rt_wa(). This new generic_handle_irq_rt_wa() just calls generic_handle_irq() surrounded by raw_spin_lock_irqsave/irqrestore(). If -RT is disabled It will fallback to generic_handle_irq().
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com> --- include/linux/irqdesc.h | 5 +++++ kernel/irq/irqdesc.c | 19 +++++++++++++++++++ 2 files changed, 24 insertions(+)
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index 9d97cd5..beea9a5 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -131,6 +131,11 @@ static inline void generic_handle_irq_desc(unsigned int irq, struct irq_desc *de } int generic_handle_irq(unsigned int irq); +#ifdef CONFIG_PREEMPT_RT_FULL +int generic_handle_irq_rt_wa(unsigned int irq); +#else +#define generic_handle_irq_rt_wa generic_handle_irq +#endif #ifdef CONFIG_HANDLE_DOMAIN_IRQ /* diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index 99793b9..b77e01b 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -353,6 +353,25 @@ int generic_handle_irq(unsigned int irq) } EXPORT_SYMBOL_GPL(generic_handle_irq); +#ifdef CONFIG_PREEMPT_RT_FULL +int generic_handle_irq_rt_wa(unsigned int irq) +{ + struct irq_desc *desc = irq_to_desc(irq); + DEFINE_RAW_SPINLOCK(wa_lock); + unsigned long wa_lock_flags; + + if (!desc) + return -EINVAL; + + raw_spin_lock_irqsave(&wa_lock, wa_lock_flags); + generic_handle_irq_desc(irq, desc); + raw_spin_unlock_irqrestore(&wa_lock, wa_lock_flags); + + return 0; +} +EXPORT_SYMBOL_GPL(generic_handle_irq_rt_wa); +#endif + #ifdef CONFIG_HANDLE_DOMAIN_IRQ /** * __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain -- 2.6.2
| |