| Message ID | 20220223154405.54912-2-maz@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | gpiolib: Handle immutable irq_chip structures | expand |
On Wed, Feb 23, 2022 at 10:40 AM Marc Zyngier <maz@kernel.org> wrote: > > In order to move away from gpiolib messing with the internals of > unsuspecting irqchips, add a flag by which irqchips advertise > that they are not to be messed with, and do solemnly swear that > they correctly call into the gpiolib helpers wueh required. "wueh"? Should that be "when"?
On 2022-02-23 17:48, Jeffrey Hugo wrote: > On Wed, Feb 23, 2022 at 10:40 AM Marc Zyngier <maz@kernel.org> wrote: >> >> In order to move away from gpiolib messing with the internals of >> unsuspecting irqchips, add a flag by which irqchips advertise >> that they are not to be messed with, and do solemnly swear that >> they correctly call into the gpiolib helpers wueh required. > > "wueh"? Should that be "when"? Absolutely. There are more typos in this cover letter, and probably even more in the individual patches! M.
On Wed, Feb 23, 2022 at 03:44:01PM +0000, Marc Zyngier wrote: > In order to move away from gpiolib messing with the internals of > unsuspecting irqchips, add a flag by which irqchips advertise > that they are not to be messed with, and do solemnly swear that > they correctly call into the gpiolib helpers wueh required. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > drivers/gpio/gpiolib.c | 7 ++++++- > include/linux/irq.h | 2 ++ > kernel/irq/debugfs.c | 1 + > 3 files changed, 9 insertions(+), 1 deletion(-) I kind of like this. The bit where the const cast is essentially guarded by an "immutable" flag is a bit funky, but it doesn't look like there is a good way to do it by making all references const without doing a huge all-at-once conversion. I've always found it a bit irritating that irq_chip was somewhere between a container for chip-specific data and an "ops" structure. I think it'd be even nicer if this was split into an extra struct irq_chip_ops, which could then always be const and a struct irq_chip that contained primarily chip-specific data as well as a pointer to struct irq_chip_ops. But again, this seems fairly tricky to pull off given all the interdependencies and we can iterate on this in the future, so this seems like a good enough compromise: Acked-by: Thierry Reding <treding@nvidia.com>
On Thu, 24 Feb 2022 16:51:41 +0000, Thierry Reding <thierry.reding@gmail.com> wrote: > > On Wed, Feb 23, 2022 at 03:44:01PM +0000, Marc Zyngier wrote: > > In order to move away from gpiolib messing with the internals of > > unsuspecting irqchips, add a flag by which irqchips advertise > > that they are not to be messed with, and do solemnly swear that > > they correctly call into the gpiolib helpers wueh required. > > > > Signed-off-by: Marc Zyngier <maz@kernel.org> > > --- > > drivers/gpio/gpiolib.c | 7 ++++++- > > include/linux/irq.h | 2 ++ > > kernel/irq/debugfs.c | 1 + > > 3 files changed, 9 insertions(+), 1 deletion(-) > > I kind of like this. The bit where the const cast is essentially guarded > by an "immutable" flag is a bit funky, but it doesn't look like there is > a good way to do it by making all references const without doing a huge > all-at-once conversion. Exactly. Somehow, we need to advertise it to the gpiolib code, and this does the job. I hope to be able to simply drop it once everthing is converted. One day. > I've always found it a bit irritating that irq_chip was somewhere > between a container for chip-specific data and an "ops" structure. I > think it'd be even nicer if this was split into an extra struct > irq_chip_ops, which could then always be const and a struct irq_chip > that contained primarily chip-specific data as well as a pointer to > struct irq_chip_ops. But that's the thing: it almost is a pure 'ops' structure. Only two things are getting in the way of it: - the 'parent_dev' field: this is now sorted, as I moved it to the irq_domain structure, and updated all the relevant drivers (see what is currently in -next). - the .name field: it really should never be something that changes from one instance of the chip to another. Which is why we have the .irq_print_chip() method to handle that (and ideally we'd stick to pure const names). I'm addressing this as I go, but everything in drivers/irqchip/ should be fixed in -next. The "context" part really lives in irq_domain. > But again, this seems fairly tricky to pull off given all the > interdependencies and we can iterate on this in the future, so this > seems like a good enough compromise: > > Acked-by: Thierry Reding <treding@nvidia.com> Thanks, M.
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 3859911b61e9..515838708b00 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1475,6 +1475,11 @@ static void gpiochip_set_irq_hooks(struct gpio_chip *gc) { struct irq_chip *irqchip = gc->irq.chip; + if (irqchip->flags & IRQCHIP_IMMUTABLE) { + chip_info(gc, "Immutable chip, not updating\n"); + return; + } + if (!irqchip->irq_request_resources && !irqchip->irq_release_resources) { irqchip->irq_request_resources = gpiochip_irq_reqres; @@ -1633,7 +1638,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gc) irq_domain_remove(gc->irq.domain); } - if (irqchip) { + if (irqchip && !(irqchip->flags & IRQCHIP_IMMUTABLE)) { if (irqchip->irq_request_resources == gpiochip_irq_reqres) { irqchip->irq_request_resources = NULL; irqchip->irq_release_resources = NULL; diff --git a/include/linux/irq.h b/include/linux/irq.h index f92788ccdba2..505308253d23 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -569,6 +569,7 @@ struct irq_chip { * IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND: Invokes __enable_irq()/__disable_irq() for wake irqs * in the suspend path if they are in disabled state * IRQCHIP_AFFINITY_PRE_STARTUP: Default affinity update before startup + * IRQCHIP_IMMUTABLE: Don't ever change anything in this chip */ enum { IRQCHIP_SET_TYPE_MASKED = (1 << 0), @@ -582,6 +583,7 @@ enum { IRQCHIP_SUPPORTS_NMI = (1 << 8), IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND = (1 << 9), IRQCHIP_AFFINITY_PRE_STARTUP = (1 << 10), + IRQCHIP_IMMUTABLE = (1 << 11), }; #include <linux/irqdesc.h> diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c index 2b43f5f5033d..bc8e40cf2b65 100644 --- a/kernel/irq/debugfs.c +++ b/kernel/irq/debugfs.c @@ -58,6 +58,7 @@ static const struct irq_bit_descr irqchip_flags[] = { BIT_MASK_DESCR(IRQCHIP_SUPPORTS_LEVEL_MSI), BIT_MASK_DESCR(IRQCHIP_SUPPORTS_NMI), BIT_MASK_DESCR(IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND), + BIT_MASK_DESCR(IRQCHIP_IMMUTABLE), }; static void
In order to move away from gpiolib messing with the internals of unsuspecting irqchips, add a flag by which irqchips advertise that they are not to be messed with, and do solemnly swear that they correctly call into the gpiolib helpers wueh required. Signed-off-by: Marc Zyngier <maz@kernel.org> --- drivers/gpio/gpiolib.c | 7 ++++++- include/linux/irq.h | 2 ++ kernel/irq/debugfs.c | 1 + 3 files changed, 9 insertions(+), 1 deletion(-)