genirq/kexec: Do not take the bus lock of an interrupt chip on the crash path

machine_kexec_mask_interrupts() calls irq_set_irqchip_state() for every
started interrupt. That function takes the bus lock of the chip and
desc->lock, and syncs the chip when it drops them. On the crash path
interrupts are off and the other CPUs are stopped, so a chip whose bus
transfer is completed by an interrupt never returns from the sync.

On RK3399 boards with an RK808 PMIC the RTC alarm interrupt belongs to
the regmap-irq chip of the RK808, which sits on I2C. rk808_irq_chip sets
init_ack_masked, so regmap_irq_sync_unlock() writes the ack register on
every unlock, and the I2C controller needs its own interrupt to finish
the transfer. A panic with a crash kernel loaded prints

  SMP: stopping secondary CPUs

and then nothing until the watchdog resets the board.

machine_kexec_mask_interrupts() takes neither lock for the other
operations on the descriptor. Move the search for the chip that
implements irq_set_irqchip_state() into __irq_set_irqchip_state(), which
takes no locks, and call it from machine_kexec_mask_interrupts().

Fixes: 78fd584cdec0 ("arm64: kdump: implement machine_crash_shutdown()")
Suggested-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Igor Velkov <iav@iav.lv>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261015-kexec-irq-bus-lock-v2-1-2af15f0757b6@iav.lv

0 files changed, 0 insertions, 0 deletions