Now in kernel below code pattern is used by many drivers:
static irqreturn_t driver_xx_hw_irq_handler(int irq, void *arg)
{
<read IRQ status register>
<perform HW specific operations>
for (<each set bit in IRQ status register>) {
<get Linux IRQ number>
generic_handle_irq(<Linux IRQ number>);
|- handle_simple_irq()
|-or- handle_level_irq()
|-or- handle_edge_irq()
|-handle_irq_event()
|-handle_irq_event_percpu()
===
"WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150
handle_irq_event_percpu+0x14c/0x174()
irq 460 handler irq_default_primary_handler+0x0/0x14 enabled interrupts"
===
}
}
On -RT above code will generate warnings, because driver_xx_hw_irq_handler()
will be forced threaded (by default) and, as result, generic_handle_irq()
will be called with IRQs enabled. To W/A this issue generic_handle_irq() can
be surrounded by raw_spin_lock_irqsave/irqrestore(wa_lock).
Instead of spreading this W/A directly in many drivers this series
introduces -RT specific version of generic_handle_irq() API -
generic_handle_irq_rt_wa(). This new generic_handle_irq_rt_wa() just calls
generic_handle_irq() surrounded by raw_spin_lock_irqsave/irqrestore().
If -RT is disabled It will fallback to generic_handle_irq().
And generic_handle_irq_rt_wa() is used then to W/A similar issues
in pcie-designware.c and pcie-dra7xx.c.
Grygorii Strashko (2):
genirq: introduce new generic_handle_irq_rt_wa() api
PCI: dra7xx: fix "WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150
handle_irq_event_percpu"
drivers/pci/host/pci-dra7xx.c | 3 ++-
drivers/pci/host/pcie-designware.c | 2 +-
include/linux/irqdesc.h | 5 +++++
kernel/irq/irqdesc.c | 19 +++++++++++++++++++
4 files changed, 27 insertions(+), 2 deletions(-)
--
2.6.2
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