linux-kernel - Re: [PATCH V2] PCI/portdrv: do not disable device on reboot/shutdown

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Message-ID: <82656e20-e821-1944-3399-1667ceb27719@codeaurora.org>
Date:   Thu, 24 May 2018 07:43:05 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, timur@...eaurora.org, ryan@...nie.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, stable@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Frederick Lawler <fred@...dlawl.com>,
        Dongdong Liu <liudongdong3@...wei.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        open list <linux-kernel@...r.kernel.org>,
        Don Brace <don.brace@...rosemi.com>,
        esc.storagedev@...rosemi.com, linux-scsi@...r.kernel.org
Subject: Re: [PATCH V2] PCI/portdrv: do not disable device on reboot/shutdown

On 5/23/2018 6:57 PM, Sinan Kaya wrote:
>> The crash seems to indicate that the hpsa device attempted a DMA after
>> we cleared the Root Port's PCI_COMMAND_MASTER, which means
>> hpsa_shutdown() didn't stop DMA from the device (it looks like *most*
>> shutdown methods don't disable device DMA, so it's in good company).
> All drivers are expected to shutdown DMA and interrupts in their shutdown()
> routines. They can skip removing threads, data structures etc. but DMA and
> interrupt disabling are required. This is the difference between shutdown()
> and remove() callbacks.

I found this note yesterday to see why we are not disabling the devices in the
PCI core itself. 

pci_device_remove()

	/*
	 * We would love to complain here if pci_dev->is_enabled is set, that
	 * the driver should have called pci_disable_device(), but the
	 * unfortunate fact is there are too many odd BIOS and bridge setups
	 * that don't like drivers doing that all of the time.
	 * Oh well, we can dream of sane hardware when we sleep, no matter how
	 * horrible the crap we have to deal with is when we are awake...
	 */ 

Ryan, can you discard the previous patch and test this one instead? remove() path
in hpsa driver seems to call pci_disable_device() via 

hpsa_remove_one()
	hpsa_free_pci_init()

but nothing on the shutdown path.

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 4ed3d26..3823f04 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -8651,6 +8651,7 @@ static void hpsa_shutdown(struct pci_dev *pdev)
        h->access.set_intr_mask(h, HPSA_INTR_OFF);
        hpsa_free_irqs(h);                      /* init_one 4 */
        hpsa_disable_interrupt_mode(h);         /* pci_init 2 */
+       pci_disable_device(h->pdev);
 }



-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.