When arm_ffa firmware driver module is unloaded or removed we call
__ffa_devices_unregister on all the devices on the ffa bus. It must
unregister all the devices instead it is currently just releasing the
devices without unregistering. That is pure wrong as when we try to
load the module back again, it will result in the kernel crash something
like below.
-->8
CPU: 2 PID: 232 Comm: modprobe Not tainted 5.15.0-rc2+ #169
Hardware name: FVP Base RevC (DT)
Call trace:
dump_backtrace+0x0/0x1cc
show_stack+0x18/0x64
dump_stack_lvl+0x64/0x7c
dump_stack+0x18/0x38
sysfs_create_dir_ns+0xe4/0x140
kobject_add_internal+0x170/0x358
kobject_add+0x94/0x100
device_add+0x178/0x5f0
device_register+0x20/0x30
ffa_device_register+0x80/0xcc [ffa_module]
ffa_setup_partitions+0x7c/0x108 [ffa_module]
init_module+0x290/0x2dc [ffa_module]
do_one_initcall+0xbc/0x230
do_init_module+0x58/0x304
load_module+0x15e0/0x1f68
__arm64_sys_finit_module+0xb8/0xf4
invoke_syscall+0x44/0x140
el0_svc_common+0xb4/0xf0
do_el0_svc+0x24/0x80
el0_svc+0x20/0x50
el0t_64_sync_handler+0x84/0xe4
el0t_64_sync+0x1a0/0x1a4
kobject_add_internal failed for arm-ffa-8001 with -EEXIST, don't try to
register things with the same name in the same directory.
----
Fix the issue by calling device_unregister in __ffa_devices_unregister
which will also take care of calling device_release(which is mapped to
ffa_release_device)
Link: https://lore.kernel.org/r/20210924092859.3057562-2-sudeep.holla@arm.com
Fixes: e781858488 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Currently the arm_ffa firmware driver can be built as module and hence
all the users of FFA driver. If any driver on the ffa bus is removed or
unregistered, the remove callback on all the device bound to the driver
being removed should be callback. For that to happen, we must register
a remove callback on the ffa_bus which is currently missing. This results
in the probe getting called again without the previous remove callback
on a device which may result in kernel crash.
Fix the issue by registering the remove callback on the FFA bus.
Link: https://lore.kernel.org/r/20210924092859.3057562-1-sudeep.holla@arm.com
Fixes: e781858488 ("firmware: arm_ffa: Add initial FFA bus support for device enumeration")
Reported-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
The Arm FF for Armv8-A specification has concept of endpoints or
partitions. In the Normal world, a partition could be a VM when
the Virtualization extension is enabled or the kernel itself.
In order to handle multiple partitions, we can create a FFA device for
each such partition on a dedicated FFA bus. Similarly, different drivers
requiring FFA transport can be registered on the same bus. We can match
the device and drivers using UUID. This is mostly for the in-kernel
users with FFA drivers.
Link: https://lore.kernel.org/r/20210521151033.181846-2-sudeep.holla@arm.com
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
