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From: "Ahmed S. Darwish" <>
To: Rahul Lakkireddy <>,
	Rohit Maheshwari <>,
	Vinay Kumar Yadav <>,
	Vishal Kulkarni <>,
Cc: "David S. Miller" <>,
	Jakub Kicinski <>,
	LKML <>,
	Thomas Gleixner <>,
	"Sebastian A. Siewior" <>,
	"Ahmed S. Darwish" <>
Subject: [RFC PATCH 0/3] chelsio: cxgb: Use threaded irqs
Date: Thu, 24 Dec 2020 14:11:45 +0100
Message-ID: <> (raw)


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.



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

             reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-24 13:11 Ahmed S. Darwish [this message]
2020-12-24 13:11 ` [RFC PATCH 1/3] chelsio: cxgb: Remove ndo_poll_controller() Ahmed S. Darwish
2020-12-24 13:31   ` Ahmed S. Darwish
2020-12-24 13:11 ` [RFC PATCH 2/3] chelsio: cxgb: Move slow interrupt handling to threaded irqs Ahmed S. Darwish
2021-01-11 10:38   ` Sebastian A. Siewior
2020-12-24 13:11 ` [RFC PATCH 3/3] chelsio: cxgb: Do not schedule a workqueue for external interrupts Ahmed S. Darwish

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