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SubjectRe: [PATCH] IB/hfi1: Fix potential deadlock on &irq_src_lock and &dd->uctxt_lock
On Tue, Sep 26, 2023 at 10:11:16AM +0000, Chengfeng Ye wrote:
> handle_receive_interrupt_napi_sp() running inside interrupt handler
> could introduce inverse lock ordering between &dd->irq_src_lock
> and &dd->uctxt_lock, if read_mod_write() is preempted by the isr.
>
> [CPU0] | [CPU1]
> hfi1_ipoib_dev_open() |
> --> hfi1_netdev_enable_queues() |
> --> enable_queues(rx) |
> --> hfi1_rcvctrl() |
> --> set_intr_bits() |
> --> read_mod_write() |
> --> spin_lock(&dd->irq_src_lock) |
> | hfi1_poll()
> | --> poll_next()
> | --> spin_lock_irq(&dd->uctxt_lock)
> |
> | --> hfi1_rcvctrl()
> | --> set_intr_bits()
> | --> read_mod_write()
> | --> spin_lock(&dd->irq_src_lock)
> <interrupt> |
> --> handle_receive_interrupt_napi_sp() |
> --> set_all_fastpath() |
> --> hfi1_rcd_get_by_index() |
> --> spin_lock_irqsave(&dd->uctxt_lock) |
>
> This flaw was found by an experimental static analysis tool I am
> developing for irq-related deadlock.
>
> To prevent the potential deadlock, the patch use spin_lock_irqsave()
> on &dd->irq_src_lock inside read_mod_write() to prevent the possible
> deadlock scenario.
>
> Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
> ---
> drivers/infiniband/hw/hfi1/chip.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)

Dennis? This needs your ack/nack

Thanks,
Jason

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