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Message-ID: <06144079-786f-d2b3-e07e-cdea5a55ba0a@cornelisnetworks.com>
Date: Tue, 24 Oct 2023 11:26:09 -0400
From: Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
To: Jason Gunthorpe <jgg@...dia.com>,
Chengfeng Ye <dg573847474@...il.com>
Cc: leon@...nel.org, dean.luick@...nelisnetworks.com,
linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] IB/hfi1: Fix potential deadlock on &irq_src_lock and
&dd->uctxt_lock
On 10/23/23 12:01 PM, Jason Gunthorpe wrote:
> 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@...il.com>
>> ---
>> drivers/infiniband/hw/hfi1/chip.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> Dennis? This needs your ack/nack
Looks like we need to disable the interrupt. Sorry for the delay.
Acked-by: Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
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