From: Vincent Jardin <[email protected]>
Unbinding and re-binding the root DPRC fails with:
sysfs: cannot create duplicate filename '/dev/char/10:256'
misc_register / fsl_mc_uapi_create_device_file /
dprc_setup / dprc_probe
It happens when the fsl-mc bus probe is not deferred, without SMMU:
- the dprc driver is registered at postcore_initcall,
- the DT node is populated at arch_initcall_sync,
- the root DPRC probes right there, before misc_init() has
registered misc_class at subsys_initcall.
misc_register() still succeeds but the device gets
no class, so misc_deregister() at unbind cannot find it:
the minor is freed while the device and its /sys/dev/char/ link leak,
and then the next bind collides on the same minor.
Let's move the dprc and allocator drivers registration, and
platform_driver_register(), to subsys_initcall_sync, after misc_init()
at subsys_initcall.
bus_register() and the platform-bus notifier stay at postcore_initcall
so that fsl_mc_bus_notifier() still pauses the MC before the SMMU is probed.
Cc: [email protected] # niche: root DPRC unbind/rebind only
Fixes: 2cf1e703f066 ("bus: fsl-mc: add fsl-mc userspace support")
Signed-off-by: Vincent Jardin <[email protected]>
---
Issue found when unbinding/rebinding the root DPRC on an LX2160A.
The failure is silent at bind time and only shows up as a
duplicate /dev/char entry on the second bind.
---
Changes in v2:
- Commit message: the bug needs a non-deferred fsl-mc bus
probe (no SMMU) - Ioana Ciornei
- No code change
- Link to v1:
https://lore.kernel.org/r/20260901-for-upstream-fsl-mc-initcall-order-v1-1-36ffe48f7...@free.fr
---
drivers/bus/fsl-mc/fsl-mc-bus.c | 40 ++++++++++++++++++++++++----------------
1 file changed, 24 insertions(+), 16 deletions(-)
diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index 66a4fa73c5b86..7f283844e4500 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -1264,35 +1264,43 @@ static int __init fsl_mc_bus_driver_init(void)
error = bus_register(&fsl_mc_bus_type);
if (error < 0) {
pr_err("bus type registration failed: %d\n", error);
- goto error_cleanup_cache;
+ return error;
}
- error = platform_driver_register(&fsl_mc_bus_driver);
- if (error < 0) {
- pr_err("platform_driver_register() failed: %d\n", error);
+ error = bus_register_notifier(&platform_bus_type, &fsl_mc_nb);
+ if (error < 0)
goto error_cleanup_bus;
- }
+
+ return 0;
+
+error_cleanup_bus:
+ bus_unregister(&fsl_mc_bus_type);
+ return error;
+}
+postcore_initcall(fsl_mc_bus_driver_init);
+
+static int __init fsl_mc_bus_drivers_init(void)
+{
+ int error;
error = dprc_driver_init();
if (error < 0)
- goto error_cleanup_driver;
+ return error;
error = fsl_mc_allocator_driver_init();
if (error < 0)
goto error_cleanup_dprc_driver;
- return bus_register_notifier(&platform_bus_type, &fsl_mc_nb);
+ error = platform_driver_register(&fsl_mc_bus_driver);
+ if (error < 0) {
+ pr_err("platform_driver_register() failed: %d\n", error);
+ goto error_cleanup_dprc_driver;
+ }
+
+ return 0;
error_cleanup_dprc_driver:
dprc_driver_exit();
-
-error_cleanup_driver:
- platform_driver_unregister(&fsl_mc_bus_driver);
-
-error_cleanup_bus:
- bus_unregister(&fsl_mc_bus_type);
-
-error_cleanup_cache:
return error;
}
-postcore_initcall(fsl_mc_bus_driver_init);
+subsys_initcall_sync(fsl_mc_bus_drivers_init);
---
base-commit: 786262be6048deab760f68c8acc2c85607165894
change-id: 20260922-for-upstream-fsl-mc-initcall-order-e3316390712b
Best regards,
--
Vincent Jardin <[email protected]>
