[PATCH] p2sb: Don't init until unassigned resources have been assigned.

bcfradella
2024-05-09T16:49:54Z

From: Ben Fradella <bfradell@netapp.com>

The P2SB could get an invalid BAR from the BIOS, and that won't be fixed
up until pcibios_assign_resources(), which is an fs_initcall().

- Move p2sb_fs_init() to an fs_initcall_sync(). This is still early
enough to avoid a race with any dependent drivers.

- Add a check for IORESOURCE_UNSET in p2sb_valid_resource() to catch
unset BARs going forward.

- Return error values from p2sb_fs_init() so that the 'initcall_debug'
cmdline arg provides useful data.

Signed-off-by: Ben Fradella <bfradell@netapp.com>
---
drivers/platform/x86/p2sb.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/platform/x86/p2sb.c b/drivers/platform/x86/p2sb.c
index 3d66e1d4eb1f..1938a3ef9480 100644
--- a/drivers/platform/x86/p2sb.c
+++ b/drivers/platform/x86/p2sb.c
@@ -56,12 +56,9 @@ static int p2sb_get_devfn(unsigned int *devfn)
return 0;
}

-static bool p2sb_valid_resource(struct resource *res)
+static bool p2sb_valid_resource(const struct resource *res)
{
- if (res->flags)
- return true;
-
- return false;
+ return res->flags & ~IORESOURCE_UNSET;
}

/* Copy resource from the first BAR of the device in question */
@@ -220,16 +217,20 @@ EXPORT_SYMBOL_GPL(p2sb_bar);

static int __init p2sb_fs_init(void)
{
- p2sb_cache_resources();
- return 0;
+ return p2sb_cache_resources();
}

/*
- * pci_rescan_remove_lock to avoid access to unhidden P2SB devices can
- * not be locked in sysfs pci bus rescan path because of deadlock. To
- * avoid the deadlock, access to P2SB devices with the lock at an early
- * step in kernel initialization and cache required resources. This
- * should happen after subsys_initcall which initializes PCI subsystem
- * and before device_initcall which requires P2SB resources.
+ * pci_rescan_remove_lock() can not be locked in sysfs pci bus rescan path
+ * because of deadlock. To avoid the deadlock, access P2SB devices with the lock
+ * at an early step in kernel initialization and cache required resources.
+ *
+ * We want to run as early as possible. If the P2SB was assigned a bad BAR,
+ * we'll need to wait on pcibios_assign_resources() to fix it. So, our list of
+ * initcall dependencies looks something like this:
+ *
+ * ...
+ * subsys_initcall (pci_subsys_init)
+ * fs_initcall (pcibios_assign_resources)
*/
-fs_initcall(p2sb_fs_init);
+fs_initcall_sync(p2sb_fs_init);
--
2.43.0