From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: "Krzysztof Wilczyński" <kw@linux.com>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Kees Cook" <keescook@chromium.org>,
"Pali Rohár" <pali@kernel.org>,
"Oliver O'Halloran" <oohall@gmail.com>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH v3 0/2] Allow deferred execution of iomem_get_mapping()
Date: Fri, 30 Jul 2021 07:06:26 +0200 [thread overview]
Message-ID: <YQOI0qdVK0dudSbx@kroah.com> (raw)
In-Reply-To: <20210729233235.1508920-1-kw@linux.com>
On Thu, Jul 29, 2021 at 11:32:33PM +0000, Krzysztof Wilczyński wrote:
> Hello,
>
> At the moment, the dependency on iomem_get_mapping() that is currently
> used in the pci_create_resource_files() and pci_create_legacy_files()
> stops us from completely retiring the late_initcall() that is used to
> invoke pci_sysfs_init() when creating sysfs object for PCI devices.
>
> This dependency on iomem_get_mapping() stops us from retiring the
> late_initcall at the moment as when we convert dynamically added sysfs
> objects, that are primarily added in the pci_create_resource_files() and
> pci_create_legacy_files(), as these attributes are added before the VFS
> completes its initialisation, and since most of the PCI devices are
> typically enumerated in subsys_initcall this leads to a failure and an
> Oops related to iomem_get_mapping() access.
>
> See relevant conversations:
> https://lore.kernel.org/linux-pci/20210204165831.2703772-1-daniel.vetter@ffwll.ch/
> https://lore.kernel.org/linux-pci/20210313215747.GA2394467@bjorn-Precision-5520/
>
> After some deliberation about the problem at hand, Dan Williams
> suggested a solution to the problem, as per:
> https://lore.kernel.org/linux-pci/CAPcyv4i0y_4cMGEpNVShLUyUk3nyWH203Ry3S87BqnDJE0Rmxg@mail.gmail.com/
>
> The idea is to defer execution of the iomem_get_mapping() to only when
> the sysfs open callback is run, and thus removing the reliance of
> fs_initcalls to complete before any other sub-system that uses the
> iomem_get_mapping().
>
> Currently, the PCI sub-system will benefit the most from this change
> allowing for it to complete the transition from dynamically created to
> static sysfs objects.
>
> This series aims to take Dan Williams' idea through the finish line.
>
> Related to:
> https://lore.kernel.org/linux-pci/20210527205845.GA1421476@bjorn-Precision-5520/
> https://lore.kernel.org/linux-pci/20210507102706.7658-1-danijel.slivka@amd.com/
> https://lore.kernel.org/linux-pci/20200716110423.xtfyb3n6tn5ixedh@pali/
>
> Krzysztof
>
No objection from me on these, Bjorn, mind if I take them through my
driver core tree?
thanks,
greg k-h
next prev parent reply other threads:[~2021-07-30 5:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-29 23:32 [PATCH v3 0/2] Allow deferred execution of iomem_get_mapping() Krzysztof Wilczyński
2021-07-29 23:32 ` [PATCH v3 1/2] sysfs: Invoke iomem_get_mapping() from the sysfs open callback Krzysztof Wilczyński
2021-07-30 19:44 ` Bjorn Helgaas
2021-07-29 23:32 ` [PATCH v3 2/2] sysfs: Rename struct bin_attribute member to f_mapping Krzysztof Wilczyński
2021-07-30 19:45 ` Bjorn Helgaas
2021-07-30 5:06 ` Greg Kroah-Hartman [this message]
2021-07-30 19:50 ` [PATCH v3 0/2] Allow deferred execution of iomem_get_mapping() Bjorn Helgaas
2021-08-05 12:43 ` Greg Kroah-Hartman
2021-08-06 11:05 ` Greg Kroah-Hartman
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