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From: Arnd Bergmann <arnd@arndb.de>
To: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: linux-pci <linux-pci@vger.kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Will Deacon <Will.Deacon@arm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linaro-kernel <linaro-kernel@lists.linaro.org>,
	Tanmay Inamdar <tinamdar@apm.com>,
	Grant Likely <grant.likely@secretlab.ca>,
	Sinan Kaya <okaya@codeaurora.org>,
	Jingoo Han <jg1.han@samsung.com>,
	Kukjin Kim <kgene.kim@samsung.com>,
	Suravee Suthikulanit <suravee.suthikulpanit@amd.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Device Tree ML <devicetree@vger.kernel.org>,
	LAKML <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.
Date: Wed, 02 Jul 2014 14:38:04 +0200	[thread overview]
Message-ID: <4751391.BGkeOrZGt8@wuerfel> (raw)
In-Reply-To: <1404240214-9804-4-git-send-email-Liviu.Dudau@arm.com>

Some more detailed comments now

On Tuesday 01 July 2014 19:43:28 Liviu Dudau wrote:
> +/*
> + * Record the PCI IO range (expressed as CPU physical address + size).
> + * Return a negative value if an error has occured, zero otherwise
> + */
> +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> +{
> +#ifdef PCI_IOBASE
> +       struct io_range *res;

I was confused by the variable naming here: A variable named 'res' is
normally a 'struct resource'. Maybe better call this 'range'.

> +       resource_size_t allocated_size = 0;
> +
> +       /* check if the range hasn't been previously recorded */
> +       list_for_each_entry(res, &io_range_list, list) {
> +               if (addr >= res->start && addr + size <= res->start + size)
> +                       return 0;
> +               allocated_size += res->size;
> +       }

A spin_lock around the list lookup should be sufficient to get around
the race that Will mentioned.

> +       /* range not registed yet, check for available space */
> +       if (allocated_size + size - 1 > IO_SPACE_LIMIT)
> +               return -E2BIG;

It might be better to limit the size to 64K if it doesn't fit at first.


	Arnd

WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.
Date: Wed, 02 Jul 2014 14:38:04 +0200	[thread overview]
Message-ID: <4751391.BGkeOrZGt8@wuerfel> (raw)
In-Reply-To: <1404240214-9804-4-git-send-email-Liviu.Dudau@arm.com>

Some more detailed comments now

On Tuesday 01 July 2014 19:43:28 Liviu Dudau wrote:
> +/*
> + * Record the PCI IO range (expressed as CPU physical address + size).
> + * Return a negative value if an error has occured, zero otherwise
> + */
> +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> +{
> +#ifdef PCI_IOBASE
> +       struct io_range *res;

I was confused by the variable naming here: A variable named 'res' is
normally a 'struct resource'. Maybe better call this 'range'.

> +       resource_size_t allocated_size = 0;
> +
> +       /* check if the range hasn't been previously recorded */
> +       list_for_each_entry(res, &io_range_list, list) {
> +               if (addr >= res->start && addr + size <= res->start + size)
> +                       return 0;
> +               allocated_size += res->size;
> +       }

A spin_lock around the list lookup should be sufficient to get around
the race that Will mentioned.

> +       /* range not registed yet, check for available space */
> +       if (allocated_size + size - 1 > IO_SPACE_LIMIT)
> +               return -E2BIG;

It might be better to limit the size to 64K if it doesn't fit at first.


	Arnd

  parent reply	other threads:[~2014-07-02 12:39 UTC|newest]

Thread overview: 218+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-01 18:43 [PATCH v8 0/9] Support for creating generic PCI host bridges from DT Liviu Dudau
2014-07-01 18:43 ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 1/9] Fix ioport_map() for !CONFIG_GENERIC_IOMAP cases Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 2/9] pci: Export find_pci_host_bridge() function Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-02 18:06   ` Tanmay Inamdar
2014-07-02 18:06     ` Tanmay Inamdar
2014-07-02 19:12     ` Arnd Bergmann
2014-07-02 19:12       ` Arnd Bergmann
2014-07-02 20:43       ` Tanmay Inamdar
2014-07-02 20:43         ` Tanmay Inamdar
2014-07-03  9:53         ` Liviu Dudau
2014-07-03  9:53           ` Liviu Dudau
2014-07-03 10:26         ` Arnd Bergmann
2014-07-03 10:26           ` Arnd Bergmann
2014-07-07 23:27   ` Bjorn Helgaas
2014-07-07 23:27     ` Bjorn Helgaas
2014-07-07 23:27     ` Bjorn Helgaas
2014-07-08 10:42     ` Liviu Dudau
2014-07-08 10:42       ` Liviu Dudau
2014-07-08 10:42       ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 19:36   ` Arnd Bergmann
2014-07-01 19:36     ` Arnd Bergmann
2014-07-01 20:45     ` Liviu Dudau
2014-07-01 20:45       ` Liviu Dudau
2014-07-02 12:30       ` Arnd Bergmann
2014-07-02 12:30         ` Arnd Bergmann
2014-07-02 14:23         ` Liviu Dudau
2014-07-02 14:23           ` Liviu Dudau
2014-07-02 14:23           ` Liviu Dudau
2014-07-02 14:23           ` Liviu Dudau
2014-07-02 14:58           ` Arnd Bergmann
2014-07-02 14:58             ` Arnd Bergmann
2014-07-02 14:58             ` Arnd Bergmann
2014-07-02 11:22   ` Will Deacon
2014-07-02 11:22     ` Will Deacon
2014-07-02 16:00     ` Liviu Dudau
2014-07-02 16:00       ` Liviu Dudau
2014-07-02 12:38   ` Arnd Bergmann [this message]
2014-07-02 12:38     ` Arnd Bergmann
2014-07-02 13:20     ` Liviu Dudau
2014-07-02 13:20       ` Liviu Dudau
2014-07-08  0:14   ` Bjorn Helgaas
2014-07-08  0:14     ` Bjorn Helgaas
2014-07-08  7:00     ` Arnd Bergmann
2014-07-08  7:00       ` Arnd Bergmann
2014-07-08 21:29       ` Bjorn Helgaas
2014-07-08 21:29         ` Bjorn Helgaas
2014-07-08 22:45         ` Liviu Dudau
2014-07-08 22:45           ` Liviu Dudau
2014-07-09  6:32           ` Arnd Bergmann
2014-07-09  6:32             ` Arnd Bergmann
2014-07-09  6:32             ` Arnd Bergmann
2014-07-09  9:13             ` Liviu Dudau
2014-07-09  9:13               ` Liviu Dudau
2014-07-09  6:20         ` Arnd Bergmann
2014-07-09  6:20           ` Arnd Bergmann
2014-07-09  9:14           ` Liviu Dudau
2014-07-09  9:14             ` Liviu Dudau
2014-07-09 15:21           ` Bjorn Helgaas
2014-07-09 15:21             ` Bjorn Helgaas
2014-07-08 10:40     ` Liviu Dudau
2014-07-08 10:40       ` Liviu Dudau
2014-07-08 14:14       ` Arnd Bergmann
2014-07-08 14:14         ` Arnd Bergmann
2014-07-09  8:59         ` Liviu Dudau
2014-07-09  8:59           ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 4/9] pci: OF: Fix the conversion of IO ranges into IO resources Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-05 19:25   ` Rob Herring
2014-07-05 19:25     ` Rob Herring
2014-07-05 19:25     ` Rob Herring
2014-07-05 20:46     ` Arnd Bergmann
2014-07-05 20:46       ` Arnd Bergmann
2014-07-07 11:11       ` Liviu Dudau
2014-07-07 11:11         ` Liviu Dudau
2014-07-07 11:11         ` Liviu Dudau
2014-07-07 21:22         ` Arnd Bergmann
2014-07-07 21:22           ` Arnd Bergmann
2014-07-07 21:22           ` Arnd Bergmann
2014-07-08 10:03           ` Liviu Dudau
2014-07-08 10:03             ` Liviu Dudau
2014-07-08 10:03             ` Liviu Dudau
2014-07-09  8:31             ` Arnd Bergmann
2014-07-09  8:31               ` Arnd Bergmann
2014-07-09  8:31               ` Arnd Bergmann
2014-07-09  9:27               ` Liviu Dudau
2014-07-09  9:27                 ` Liviu Dudau
2014-07-09  9:27                 ` Liviu Dudau
2014-07-16 14:35               ` Rob Herring
2014-07-16 14:35                 ` Rob Herring
2014-07-16 14:35                 ` Rob Herring
2014-07-16 14:47                 ` Liviu Dudau
2014-07-16 14:47                   ` Liviu Dudau
2014-07-16 14:47                   ` Liviu Dudau
2014-07-16 14:47                 ` Arnd Bergmann
2014-07-16 14:47                   ` Arnd Bergmann
2014-07-16 14:47                   ` Arnd Bergmann
2014-07-01 18:43 ` [PATCH v8 5/9] pci: Create pci_host_bridge before its associated bus in pci_create_root_bus Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 6/9] pci: Introduce a domain number for pci_host_bridge Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-08  0:59   ` Bjorn Helgaas
2014-07-08  0:59     ` Bjorn Helgaas
2014-07-08 10:46     ` Liviu Dudau
2014-07-08 10:46       ` Liviu Dudau
2014-07-08 18:41       ` Bjorn Helgaas
2014-07-08 18:41         ` Bjorn Helgaas
2014-07-08 22:48         ` Liviu Dudau
2014-07-08 22:48           ` Liviu Dudau
2014-07-09 15:10           ` Bjorn Helgaas
2014-07-09 15:10             ` Bjorn Helgaas
2014-07-10  9:47             ` Liviu Dudau
2014-07-10  9:47               ` Liviu Dudau
2014-07-10 22:36               ` Bjorn Helgaas
2014-07-10 22:36                 ` Bjorn Helgaas
2014-07-11  9:30                 ` Liviu Dudau
2014-07-11  9:30                   ` Liviu Dudau
2014-07-11  9:30                   ` Liviu Dudau
2014-07-11 14:11                 ` Catalin Marinas
2014-07-11 14:11                   ` Catalin Marinas
2014-07-11 15:08                   ` Liviu Dudau
2014-07-11 15:08                     ` Liviu Dudau
2014-07-11 16:09                     ` Catalin Marinas
2014-07-11 16:09                       ` Catalin Marinas
2014-07-11 17:02                   ` Bjorn Helgaas
2014-07-11 17:02                     ` Bjorn Helgaas
2014-07-11 18:02                     ` Catalin Marinas
2014-07-11 18:02                       ` Catalin Marinas
2014-07-14 16:39                       ` Catalin Marinas
2014-07-14 16:39                         ` Catalin Marinas
2014-07-14 16:39                         ` Catalin Marinas
2014-07-22  3:15                         ` Bjorn Helgaas
2014-07-22  3:15                           ` Bjorn Helgaas
2014-07-25 15:42                           ` Catalin Marinas
2014-07-25 15:42                             ` Catalin Marinas
2014-07-01 18:43 ` [PATCH v8 7/9] pci: of: Parse and map the IRQ when adding the PCI device Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-02 11:17   ` Will Deacon
2014-07-02 11:17     ` Will Deacon
2014-07-05 19:04     ` Rob Herring
2014-07-05 19:04       ` Rob Herring
2014-07-05 19:04       ` Rob Herring
2014-07-01 18:43 ` [PATCH v8 8/9] pci: Add support for creating a generic host_bridge from device tree Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-01 20:50   ` [RESEND] " Liviu Dudau
2014-07-01 20:50     ` Liviu Dudau
2014-07-01 20:50     ` Liviu Dudau
2014-07-01 21:04     ` Liviu Dudau
2014-07-01 21:04       ` Liviu Dudau
2014-07-01 21:04       ` Liviu Dudau
2014-07-02 11:22   ` Will Deacon
2014-07-02 11:22     ` Will Deacon
2014-07-02 17:23     ` Liviu Dudau
2014-07-02 17:23       ` Liviu Dudau
2014-07-02 17:23       ` Liviu Dudau
2014-07-02 17:31       ` Will Deacon
2014-07-02 17:31         ` Will Deacon
2014-07-02 19:09         ` Arnd Bergmann
2014-07-02 19:09           ` Arnd Bergmann
2014-07-08  1:01   ` Bjorn Helgaas
2014-07-08  1:01     ` Bjorn Helgaas
2014-07-08 10:29     ` Liviu Dudau
2014-07-08 10:29       ` Liviu Dudau
2014-07-08 21:33       ` Bjorn Helgaas
2014-07-08 21:33         ` Bjorn Helgaas
2014-07-08 22:27         ` Liviu Dudau
2014-07-08 22:27           ` Liviu Dudau
2014-07-08 22:37           ` Bjorn Helgaas
2014-07-08 22:37             ` Bjorn Helgaas
2014-07-08 22:37             ` Bjorn Helgaas
2014-07-08 22:57             ` Liviu Dudau
2014-07-08 22:57               ` Liviu Dudau
2014-07-09  6:47               ` Arnd Bergmann
2014-07-09  6:47                 ` Arnd Bergmann
2014-07-11  7:43   ` Jingoo Han
2014-07-11  7:43     ` Jingoo Han
2014-07-11  9:08     ` Liviu Dudau
2014-07-11  9:08       ` Liviu Dudau
2014-07-01 18:43 ` [PATCH v8 9/9] pci: Remap I/O bus resources into CPU space with pci_remap_iospace() Liviu Dudau
2014-07-01 18:43   ` Liviu Dudau
2014-07-14 16:54   ` Catalin Marinas
2014-07-14 16:54     ` Catalin Marinas
2014-07-14 16:56     ` Liviu Dudau
2014-07-14 16:56       ` Liviu Dudau
2014-07-14 18:15     ` Arnd Bergmann
2014-07-14 18:15       ` Arnd Bergmann
2014-07-14 18:15       ` Arnd Bergmann
2014-07-15  0:14       ` Liviu Dudau
2014-07-15  0:14         ` Liviu Dudau
2014-07-15  0:14         ` Liviu Dudau
2014-07-15  9:09       ` Catalin Marinas
2014-07-15  9:09         ` Catalin Marinas
2014-07-15  9:09         ` Catalin Marinas
2014-07-06 15:23 ` [PATCH v8 0/9] Support for creating generic PCI host bridges from DT Rob Herring
2014-07-06 15:23   ` Rob Herring
2014-07-06 15:23   ` Rob Herring
2014-07-07 11:12   ` Liviu Dudau
2014-07-07 11:12     ` Liviu Dudau
2014-07-08 17:18   ` Liviu Dudau
2014-07-08 17:18     ` Liviu Dudau
2014-07-11  0:44     ` Tanmay Inamdar
2014-07-11  0:44       ` Tanmay Inamdar
2014-07-11  7:33       ` Jingoo Han
2014-07-11  7:33         ` Jingoo Han
2014-07-11  9:11         ` Liviu Dudau
2014-07-11  9:11           ` Liviu Dudau

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