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@xxxxxxxx/ 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@xxxxxxxxxxxxxx/ 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@xxxxxxx/ https://lore.kernel.org/linux-pci/20200716110423.xtfyb3n6tn5ixedh@pali/ Krzysztof --- Changes in v3: Squashed first two patches from v2 into a single patch to resolve compile time issues. Carried over Dan Williams' review from v2 as there are no code or functional changes. Changes in v2: Added "Signed-off-by" and "Reviewed-by" from Dan Williams as per his feedback. Added third patch that renames struct bin_attribute member "mapping" to "f_mapping" to keep the naming consistent with struct file. N.B. this patch can definitely be dropped as the rename is not required for anything else to work. Krzysztof Wilczyński (2): sysfs: Invoke iomem_get_mapping() from the sysfs open callback sysfs: Rename struct bin_attribute member to f_mapping drivers/pci/pci-sysfs.c | 6 +++--- fs/sysfs/file.c | 4 ++-- include/linux/sysfs.h | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) -- 2.32.0
