linux.git/kernel/irq/Kconfig, branch vsnprintf

genirq: Provide a snapshot mechanism for interrupt statistics

2024-04-12T15:08:05+00:00

The soft lockup detector lacks a mechanism to identify interrupt storms as
root cause of a lockup. To enable this the detector needs a mechanism to
snapshot the interrupt count statistics on a CPU when the detector observes
a potential lockup scenario and compare that against the interrupt count
when it warns about the lockup later on. The number of interrupts in that
period give a hint whether the lockup might have been caused by an interrupt
storm.

Instead of having extra storage in the lockup detector and accessing the
internals of the interrupt descriptor directly, add a snapshot member to
the per CPU irq_desc::kstat_irq structure and provide interfaces to take a
snapshot of all interrupts on the current CPU and to retrieve the delta of
a specific interrupt later on.

Originally-by: Thomas Gleixner 
Signed-off-by: Bitao Hu 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240411074134.30922-3-yaoma@linux.alibaba.com

genirq: Add mechanism to multiplex a single HW IPI

2023-02-05T10:57:55+00:00

All RISC-V platforms have a single HW IPI provided by the INTC local
interrupt controller. The HW method to trigger INTC IPI can be through
external irqchip (e.g. RISC-V AIA), through platform specific device
(e.g. SiFive CLINT timer), or through firmware (e.g. SBI IPI call).

To support multiple IPIs on RISC-V, add a generic IPI multiplexing
mechanism which help us create multiple virtual IPIs using a single
HW IPI. This generic IPI multiplexing is inspired by the Apple AIC
irqchip driver and it is shared by various RISC-V irqchip drivers.

Signed-off-by: Anup Patel 
Reviewed-by: Hector Martin 
Tested-by: Hector Martin 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20230103141221.772261-4-apatel@ventanamicro.com

genirq: Get rid of GENERIC_MSI_IRQ_DOMAIN

2022-11-17T14:15:20+00:00

Adjust to reality and remove another layer of pointless Kconfig
indirection. CONFIG_GENERIC_MSI_IRQ is good enough to serve
all purposes.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Jason Gunthorpe 
Link: https://lore.kernel.org/r/20221111122014.524842979@linutronix.de

genirq: GENERIC_IRQ_EFFECTIVE_AFF_MASK depends on SMP

2022-07-07T08:38:04+00:00

An IRQ's effective affinity can only be different from its configured
affinity if there are multiple CPUs. Make it clear that this option is
only meaningful when SMP is enabled. Most of the relevant code in
irqdesc.c is already hidden behind CONFIG_SMP anyway.

Signed-off-by: Samuel Holland 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220701200056.46555-4-samuel@sholland.org

genirq: GENERIC_IRQ_IPI depends on SMP

2022-07-07T08:38:03+00:00

The generic IPI code depends on the IRQ affinity mask being allocated
and initialized. This will not be the case if SMP is disabled. Fix up
the remaining driver that selected GENERIC_IRQ_IPI in a non-SMP config.

Reported-by: kernel test robot 
Signed-off-by: Samuel Holland 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220701200056.46555-3-samuel@sholland.org

Merge branch irq/irq_cpu_offline into irq/irqchip-next

2021-10-28T12:34:57+00:00

* irq/irq_cpu_offline:
  : .
  : Make irq_cpu_{on,off}line() deprecated kernel API, and only
  : enable it for some obscure Cavium platform after having
  : moved all the other users away from it.
  :
  : Next step, drop the platform itself.
  : .
  genirq: Hide irq_cpu_{on,off}line() behind a deprecated option
  irqchip/mips-gic: Get rid of the reliance on irq_cpu_online()
  MIPS: loongson64: Drop call to irq_cpu_offline()

Signed-off-by: Marc Zyngier

genirq: Hide irq_cpu_{on,off}line() behind a deprecated option

2021-10-26T10:19:55+00:00

irq_cpu_{on,off}line() are now only used by the Octeon platform.
Make their use conditional on this plaform being enabled, and
otherwise hidden away.

Signed-off-by: Marc Zyngier 
Reviewed-by: Florian Fainelli 
Tested-by: Serge Semin 
Link: https://lore.kernel.org/r/20211021170414.3341522-4-maz@kernel.org

irq: remove handle_domain_{irq,nmi}()

2021-10-26T09:13:31+00:00

Now that entry code handles IRQ entry (including setting the IRQ regs)
before calling irqchip code, irqchip code can safely call
generic_handle_domain_irq(), and there's no functional reason for it to
call handle_domain_irq().

Let's cement this split of responsibility and remove handle_domain_irq()
entirely, updating irqchip drivers to call generic_handle_domain_irq().

For consistency, handle_domain_nmi() is similarly removed and replaced
with a generic_handle_domain_nmi() function which also does not perform
any entry logic.

Previously handle_domain_{irq,nmi}() had a WARN_ON() which would fire
when they were called in an inappropriate context. So that we can
identify similar issues going forward, similar WARN_ON_ONCE() logic is
added to the generic_handle_*() functions, and comments are updated for
clarity and consistency.

Signed-off-by: Mark Rutland 
Reviewed-by: Marc Zyngier 
Cc: Thomas Gleixner

irq: add a (temporary) CONFIG_HANDLE_DOMAIN_IRQ_IRQENTRY

2021-10-25T09:05:30+00:00

Going forward we want architecture/entry code to perform all the
necessary work to enter/exit IRQ context, with irqchip code merely
handling the mapping of the interrupt to any handler(s). Among other
reasons, this is necessary to consistently fix some longstanding issues
with the ordering of lockdep/RCU/tracing instrumentation which many
architectures get wrong today in their entry code.

Importantly, rcu_irq_{enter,exit}() must be called precisely once per
IRQ exception, so that rcu_is_cpu_rrupt_from_idle() can correctly
identify when an interrupt was taken from an idle context which must be
explicitly preempted. Currently handle_domain_irq() calls
rcu_irq_{enter,exit}() via irq_{enter,exit}(), but entry code needs to
be able to call rcu_irq_{enter,exit}() earlier for correct ordering
across lockdep/RCU/tracing updates for sequences such as:

  lockdep_hardirqs_off(CALLER_ADDR0);
  rcu_irq_enter();
  trace_hardirqs_off_finish();

To permit each architecture to be converted to the new style in turn,
this patch adds a new CONFIG_HANDLE_DOMAIN_IRQ_IRQENTRY selected by all
current users of HANDLE_DOMAIN_IRQ, which gates the existing behaviour.
When CONFIG_HANDLE_DOMAIN_IRQ_IRQENTRY is not selected,
handle_domain_irq() requires entry code to perform the
irq_{enter,exit}() work, with an explicit check for this matching the
style of handle_domain_nmi().

Subsequent patches will:

1) Add the necessary IRQ entry accounting to each architecture in turn,
   dropping CONFIG_HANDLE_DOMAIN_IRQ_IRQENTRY from that architecture's
   Kconfig.

2) Remove CONFIG_HANDLE_DOMAIN_IRQ_IRQENTRY once it is no longer
   selected.

3) Convert irqchip drivers to consistently use
   generic_handle_domain_irq() rather than handle_domain_irq().

4) Remove handle_domain_irq() and CONFIG_HANDLE_DOMAIN_IRQ.

... which should leave us with a clear split of responsiblity across the
entry and irqchip code, making it possible to perform additional
cleanups and fixes for the aforementioned longstanding issues with entry
code.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland 
Reviewed-by: Marc Zyngier 
Cc: Thomas Gleixner

powerpc: Move the use of irq_domain_add_nomap() behind a config option

2021-06-10T12:09:17+00:00

Only a handful of old PPC systems are still using the old 'nomap'
variant of the irqdomain library. Move the associated definitions
behind a configuration option, which will allow us to make some
more radical changes.

Signed-off-by: Marc Zyngier