[RFC PATCH 0/3] chelsio: cxgb: Use threaded irqs

Ahmed S. Darwish
2020-12-24T13:12:51Z

Folks,

The t1_interrupt() irq handler calls del_timer_sync() down the chain:

sge.c: t1_interrupt()
-> subr.c: t1_slow_intr_handler()
-> asic_slow_intr() || fpga_slow_intr()
-> t1_pci_intr_handler()
-> cxgb2.c: t1_fatal_err() # Cont. at [*]
-> fpga_slow_intr()
-> sge.c: t1_sge_intr_error_handler()
-> cxgb2.c: t1_fatal_err() # Cont. at [*]

[*] cxgb2.c: t1_fatal_err()
-> sge.c: t1_sge_stop()
-> timer.c: del_timer_sync()

This is invalid: if an irq handler calls del_timer_sync() on a timer
it has already interrupted, it will just loop forever. That's why
del_timer_sync() also has a WARN_ON(in_irq()).

Included is an RFC patch series that runs the interrupt handler slow
path, t1_slow_intr_handler(), in a threaded-irq context.

This also leads to nice code savings across the driver, as some
workqueues and spinlocks are no longer needed.

Note: Only compile-tested. I do not have the hardware in question.

Thanks,

8<--------------

Ahmed S. Darwish (3):
chelsio: cxgb: Remove ndo_poll_controller()
chelsio: cxgb: Move slow interrupt handling to threaded irqs
chelsio: cxgb: Do not schedule a workqueue for external interrupts

drivers/net/ethernet/chelsio/cxgb/common.h | 2 -
drivers/net/ethernet/chelsio/cxgb/cxgb2.c | 58 ++--------------------
drivers/net/ethernet/chelsio/cxgb/sge.c | 25 +++++++---
drivers/net/ethernet/chelsio/cxgb/sge.h | 3 +-
drivers/net/ethernet/chelsio/cxgb/subr.c | 2 +-
5 files changed, 25 insertions(+), 65 deletions(-)

base-commit: 2c85ebc57b3e1817b6ce1a6b703928e113a90442
--
2.29.2