linux-kernel - Re: [Update][PATCH 8/9] powerpc / eeh_driver: Use global PCI rescan-remove locking

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Message-ID: <20140115173823.GA24030@google.com>
Date:	Wed, 15 Jan 2014 10:38:23 -0700
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Yinghai Lu <yinghai@...nel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Gu Zheng <guz.fnst@...fujitsu.com>,
	Guo Chao <yan@...ux.vnet.ibm.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Myron Stowe <myron.stowe@...il.com>,
	Benjamin Herrenschmidt <benh@....ibm.com>,
	linux-scsi@...r.kernel.org, Matthew Garrett <mjg59@...f.ucam.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Subject: Re: [Update][PATCH 8/9] powerpc / eeh_driver: Use global PCI
 rescan-remove locking

On Wed, Jan 15, 2014 at 02:36:36PM +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Subject: powerpc / eeh_driver: Use global PCI rescan-remove locking
> 
> Race conditions are theoretically possible between the PCI device
> addition and removal in the PPC64 PCI error recovery driver and
> the generic PCI bus rescan and device removal that can be triggered
> via sysfs.
> 
> To avoid those race conditions make PPC64 PCI error recovery driver
> use global PCI rescan-remove locking around PCI device addition and
> removal.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> 
> The previous version had wrong function names in the last hunk, sorry about
> that.

I replaced the previous version and re-pushed the pci/locking branch,
thanks!

> 
> Rafael
> 
> ---
>  arch/powerpc/kernel/eeh_driver.c |   19 ++++++++++++++++---
>  1 file changed, 16 insertions(+), 3 deletions(-)
> 
> Index: linux-pm/arch/powerpc/kernel/eeh_driver.c
> ===================================================================
> --- linux-pm.orig/arch/powerpc/kernel/eeh_driver.c
> +++ linux-pm/arch/powerpc/kernel/eeh_driver.c
> @@ -369,7 +369,9 @@ static void *eeh_rmv_device(void *data,
>  	edev->mode |= EEH_DEV_DISCONNECTED;
>  	(*removed)++;
>  
> +	pci_lock_rescan_remove();
>  	pci_stop_and_remove_bus_device(dev);
> +	pci_unlock_rescan_remove();
>  
>  	return NULL;
>  }
> @@ -416,10 +418,13 @@ static int eeh_reset_device(struct eeh_p
>  	 * into pcibios_add_pci_devices().
>  	 */
>  	eeh_pe_state_mark(pe, EEH_PE_KEEP);
> -	if (bus)
> +	if (bus) {
> +		pci_lock_rescan_remove();
>  		pcibios_remove_pci_devices(bus);
> -	else if (frozen_bus)
> +		pci_unlock_rescan_remove();
> +	} else if (frozen_bus) {
>  		eeh_pe_dev_traverse(pe, eeh_rmv_device, &removed);
> +	}
>  
>  	/* Reset the pci controller. (Asserts RST#; resets config space).
>  	 * Reconfigure bridges and devices. Don't try to bring the system
> @@ -429,6 +434,8 @@ static int eeh_reset_device(struct eeh_p
>  	if (rc)
>  		return rc;
>  
> +	pci_lock_rescan_remove();
> +
>  	/* Restore PE */
>  	eeh_ops->configure_bridge(pe);
>  	eeh_pe_restore_bars(pe);
> @@ -462,6 +469,7 @@ static int eeh_reset_device(struct eeh_p
>  	pe->tstamp = tstamp;
>  	pe->freeze_count = cnt;
>  
> +	pci_unlock_rescan_remove();
>  	return 0;
>  }
>  
> @@ -618,8 +626,11 @@ perm_error:
>  	eeh_pe_dev_traverse(pe, eeh_report_failure, NULL);
>  
>  	/* Shut down the device drivers for good. */
> -	if (frozen_bus)
> +	if (frozen_bus) {
> +		pci_lock_rescan_remove();
>  		pcibios_remove_pci_devices(frozen_bus);
> +		pci_unlock_rescan_remove();
> +	}
>  }
>  
>  static void eeh_handle_special_event(void)
> @@ -692,6 +703,7 @@ static void eeh_handle_special_event(voi
>  	if (rc == 2 || rc == 1)
>  		eeh_handle_normal_event(pe);
>  	else {
> +		pci_lock_rescan_remove();
>  		list_for_each_entry_safe(hose, tmp,
>  			&hose_list, list_node) {
>  			phb_pe = eeh_phb_pe_get(hose);
> @@ -703,6 +715,7 @@ static void eeh_handle_special_event(voi
>  			eeh_pe_dev_traverse(pe, eeh_report_failure, NULL);
>  			pcibios_remove_pci_devices(bus);
>  		}
> +		pci_unlock_rescan_remove();
>  	}
>  }
>  
> 
> --
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