On Sat, Dec 05, 2020 at 05:19:18PM +0100, Thomas Gleixner wrote: > On Fri, Dec 04 2020 at 21:19, Oleksandr Natalenko wrote: > > On Thu, Dec 03, 2020 at 07:04:00PM +0000, bugzilla-daemon@xxxxxxxxxxxxxxxxxxx wrote: > >> 2) Have a wrapper around handle_generic_irq() which ensures that > >> interrupts are disabled before invoking it. > > > The question is whether it's guaranteed under all circumstances > > including forced irq threading. The i801 driver has assumptions about > > this, so I wouldn't be surprised if there are more. > > Assuming that a final answer might take some time, the below which > implements #2 will make it at least work for now. > > Thanks, > > tglx > --- > Subject: genirq, i2c: Provide and use generic_dispatch_irq() > From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Date: Thu, 03 Dec 2020 19:12:24 +0100 > > Carlos reported that on his system booting with 'threadirqs' on the command > line result in the following warning: > > irq 31 handler irq_default_primary_handler+0x0/0x10 enabled interrupts > WARNING: CPU: 2 PID: 989 at kernel/irq/handle.c:153 __handle_irq_event_percpu+0x19f/0x1b0 > > The reason is in the i2c stack: > > i801_isr() > i801_host_notify_isr() > i2c_handle_smbus_host_notify() > generic_handle_irq() > > and that explodes with forced interrupt threading because it's called with > interrupts enabled. > > It would be possible to set IRQF_NO_THREAD on the i801 interrupt to exclude > it from force threading, but that would break on RT and require a larger > update. > > It's also unclear whether there are other drivers which can reach that code > path via i2c_slave_host_notify_cb(). As there are enough i2c drivers which > use threaded interrupt handlers by default it seems not completely > impossible that this can happen even without force threaded interrupts. > > For a quick fix provide a wrapper around generic_handle_irq() which has a > local_irq_save/restore() around the invocation and use it in the i2c code. > > Reported-by: Carlos Jimenez <javashin1986@xxxxxxxxx> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=202453 > --- > drivers/i2c/i2c-core-base.c | 2 +- > include/linux/irqdesc.h | 1 + > kernel/irq/irqdesc.c | 20 ++++++++++++++++++++ > 3 files changed, 22 insertions(+), 1 deletion(-) > > --- a/drivers/i2c/i2c-core-base.c > +++ b/drivers/i2c/i2c-core-base.c > @@ -1385,7 +1385,7 @@ int i2c_handle_smbus_host_notify(struct > if (irq <= 0) > return -ENXIO; > > - generic_handle_irq(irq); > + generic_dispatch_irq(irq); > > return 0; > } > --- a/include/linux/irqdesc.h > +++ b/include/linux/irqdesc.h > @@ -153,6 +153,7 @@ static inline void generic_handle_irq_de > } > > int generic_handle_irq(unsigned int irq); > +int generic_dispatch_irq(unsigned int irq); > > #ifdef CONFIG_HANDLE_DOMAIN_IRQ > /* > --- a/kernel/irq/irqdesc.c > +++ b/kernel/irq/irqdesc.c > @@ -652,6 +652,26 @@ int generic_handle_irq(unsigned int irq) > } > EXPORT_SYMBOL_GPL(generic_handle_irq); > > +/** > + * generic_dispatch_irq - Dispatch an interrupt from an interrupt handler > + * @irq: The irq number to handle > + * > + * A wrapper around generic_handle_irq() which ensures that interrupts are > + * disabled when the primary handler of the dispatched irq is invoked. > + * This is useful for interrupt handlers with dispatching to be safe for > + * the forced threaded case. > + */ > +int generic_dispatch_irq(unsigned int irq) > +{ > + unsigned long flags; > + int ret; > + > + local_irq_save(&flags); > + ret = generic_handle_irq(irq); > + local_irq_restore(&flags); FWIW, for me &flags explodes build on v5.10-rc6. I had to change it to local_irq_save/restore(flags) (without taking an address via &). > + return ret; > +} > + > #ifdef CONFIG_HANDLE_DOMAIN_IRQ > /** > * __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain -- Oleksandr Natalenko (post-factum)
