On Wed, Feb 10, 2021 at 10:40 PM Bjorn Helgaas helgaas@kernel.org wrote:
On Fri, Feb 05, 2021 at 02:36:32PM +0100, Daniel Vetter wrote:
We are already doing this for all the regular sysfs files on PCI devices, but not yet on the legacy io files on the PCI buses. Thus far no problem, but in the next patch I want to wire up iomem revoke support. That needs the vfs up and running already to make sure that iomem_get_mapping() works.
Wire it up exactly like the existing code in pci_create_sysfs_dev_files(). Note that pci_remove_legacy_files() doesn't need a check since the one for pci_bus->legacy_io is sufficient.
An alternative solution would be to implement a callback in sysfs to set up the address space from iomem_get_mapping() when userspace calls mmap(). This also works, but Greg didn't really like that just to work around an ordering issue when the kernel loads initially.
v2: Improve commit message (Bjorn)
Signed-off-by: Daniel Vetter daniel.vetter@intel.com
Acked-by: Bjorn Helgaas bhelgaas@google.com
I wish we weren't extending a known-racy mechanism to do this, but at least we're not *adding* a brand new race.
Yeah it's not great. Thanks for looking at both again, I'll fix up the typos on the 2nd one and merge them both.
Cheers, Daniel
Cc: Stephen Rothwell sfr@canb.auug.org.au Cc: Jason Gunthorpe jgg@ziepe.ca Cc: Kees Cook keescook@chromium.org Cc: Dan Williams dan.j.williams@intel.com Cc: Andrew Morton akpm@linux-foundation.org Cc: John Hubbard jhubbard@nvidia.com Cc: Jérôme Glisse jglisse@redhat.com Cc: Jan Kara jack@suse.cz Cc: Dan Williams dan.j.williams@intel.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Bjorn Helgaas bhelgaas@google.com Cc: linux-pci@vger.kernel.org
drivers/pci/pci-sysfs.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index fb072f4b3176..0c45b4f7b214 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -927,6 +927,9 @@ void pci_create_legacy_files(struct pci_bus *b) { int error;
if (!sysfs_initialized)return;b->legacy_io = kcalloc(2, sizeof(struct bin_attribute), GFP_ATOMIC); if (!b->legacy_io)@@ -1448,6 +1451,7 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev) static int __init pci_sysfs_init(void) { struct pci_dev *pdev = NULL;
struct pci_bus *pbus = NULL; int retval; sysfs_initialized = 1;@@ -1459,6 +1463,9 @@ static int __init pci_sysfs_init(void) } }
while ((pbus = pci_find_next_bus(pbus)))pci_create_legacy_files(pbus);return 0;} late_initcall(pci_sysfs_init); -- 2.30.0
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