The switch to using hlist for managing software resend of interrupts
broke resend in at least two ways:

First, unconditionally adding interrupt descriptors to the resend list can
corrupt the list when the descriptor in question has already been
added. This causes the resend tasklet to loop indefinitely with interrupts
disabled as was recently reported with the Lenovo ThinkPad X13s after
threaded NAPI was disabled in the ath11k WiFi driver.

This bug is easily fixed by restoring the old semantics of irq_sw_resend()
so that it can be called also for descriptors that have already been marked
for resend.

Second, the offending commit also broke software resend of nested
interrupts by simply discarding the code that made sure that such
interrupts are retriggered using the parent interrupt.

Add back the corresponding code that adds the parent descriptor to the
resend list.

Fixes: bc06a9e08742 ("genirq: Use hlist for managing resend handlers")
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/lkml/20230809073432.4193-1-johan+linaro@kernel.org/
Link: https://lore.kernel.org/r/20230826154004.1417-1-johan+linaro@kernel.org

The current implementation utilizes a bitmap for managing interrupt resend
handlers, which is allocated based on the SPARSE_IRQ/NR_IRQS macros.
However, this method may not efficiently utilize memory during runtime,
particularly when IRQ_BITMAP_BITS is large.

Address this issue by using an hlist to manage interrupt resend handlers
instead of relying on a static bitmap memory allocation. Additionally, a
new function, clear_irq_resend(), is introduced and called from
irq_shutdown to ensure a graceful teardown of the interrupt.

Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230519134902.1495562-2-sdonthineni@nvidia.com

No functional change.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210316100205.23492-1-krzysztof.kozlowski@canonical.com

This converts the resend_tasklet to use the new API in
commit 12cc923f1ccc ("tasklet: Introduce new initialization API")

The new API changes the argument passed to the callback function, but
fortunately the argument isn't used so it is straight forward to use
DECLARE_TASKLET() rather than DECLARE_TASKLET_OLD().

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210123182456.6521-1-esmil@mailme.dk

On resending an interrupt, we only check the outermost irqchip for
a irq_retrigger callback. However, this callback could be implemented
at an inner level. Use irq_chip_retrigger_hierarchy() in this case.

Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

This converts all the existing DECLARE_TASKLET() (and ...DISABLED)
macros with DECLARE_TASKLET_OLD() in preparation for refactoring the
tasklet callback type. All existing DECLARE_TASKLET() users had a "0"
data argument, it has been removed here as well.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>

Error injection mechanisms need a half ways safe way to inject interrupts as
invoking generic_handle_irq() or the actual device interrupt handler
directly from e.g. a debugfs write is not guaranteed to be safe.

On x86 generic_handle_irq() is unsafe due to the hardware trainwreck which
is the base of x86 interrupt delivery and affinity management.

Move the irq debugfs injection code into a separate function which can be
used by error injection code as well.

The implementation prevents at least that state is corrupted, but it cannot
close a very tiny race window on x86 which might result in a stale and not
serviced device interrupt under very unlikely circumstances.

This is explicitly for debugging and testing and not for production use or
abuse in random driver code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lkml.kernel.org/r/20200306130623.990928309@linutronix.de

The code sets IRQS_REPLAY unconditionally whether the resend happens or
not. That doesn't have bad side effects right now, but inconsistent state
is always a latent source of problems.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lkml.kernel.org/r/20200306130623.882129117@linutronix.de

In preparation for an interrupt injection interface which can be used
safely by error injection mechanisms. e.g. PCI-E/ AER, add a return value
to check_irq_resend() so errors can be propagated to the caller.

Split out the software resend code so the ugly #ifdef in check_irq_resend()
goes away and the whole thing becomes readable.

Fix up the caller in debugfs. The caller in irq_startup() does not care
about the return value as this is unconditionally invoked for all
interrupts and the resend is best effort anyway.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lkml.kernel.org/r/20200306130623.775200917@linutronix.de

In general calling generic_handle_irq() with interrupts disabled from non
interrupt context is harmless. For some interrupt controllers like the x86
trainwrecks this is outright dangerous as it might corrupt state if an
interrupt affinity change is pending.

Add infrastructure which allows to mark interrupts as unsafe and catch such
usage in generic_handle_irq().

Reported-by: sathyanarayanan.kuppuswamy@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lkml.kernel.org/r/20200306130623.590923677@linutronix.de