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Message-ID: <7bb6e2c9-835c-c8d9-f8a5-baa3d3b03b12@gmail.com> Date: Thu, 11 May 2023 22:17:18 +0200 From: Heiner Kallweit <hkallweit1@...il.com> To: Lukas Wunner <lukas@...ner.de> Cc: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>, Rob Herring <robh@...nel.org>, Lorenzo Pieralisi <lorenzo.pieralisi@....com>, Krzysztof Wilczy??ski <kw@...ux.com>, nic_swsd@...ltek.com, "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 14/17] r8169: Use pcie_lnkctl_clear_and_set() for changing LNKCTL On 11.05.2023 22:02, Lukas Wunner wrote: > On Thu, May 11, 2023 at 09:49:52PM +0200, Heiner Kallweit wrote: >> On 11.05.2023 15:14, Ilpo Järvinen wrote: >>> Don't assume that only the driver would be accessing LNKCTL. ASPM >>> policy changes can trigger write to LNKCTL outside of driver's control. >>> >>> Use pcie_lnkctl_clear_and_set() which does proper locking to avoid >>> losing concurrent updates to the register value. >> >> Wouldn't it be more appropriate to add proper locking to the >> underlying pcie_capability_clear_and_set_word()? > > PCI config space accessors such as this one are also used in hot paths > (e.g. interrupt handlers). They should be kept lean (and lockless) I *think* in case the system uses threaded interrupts you may need locking also in interrupt handlers. > by default. We only need locking for specific PCIe Extended Capabilities > which are concurrently accessed by PCI core code and drivers. > > Thanks, > > Lukas
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