b71b55248a
Currently ffa_drv->remove() is called unconditionally from ffa_device_remove(). Since the driver registration doesn't check for it and allows it to be registered without .remove callback, we need to check for the presence of it before executing it from ffa_device_remove() to above a NULL pointer dereference like the one below: | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 | Mem abort info: | ESR = 0x0000000086000004 | EC = 0x21: IABT (current EL), IL = 32 bits | SET = 0, FnV = 0 | EA = 0, S1PTW = 0 | FSC = 0x04: level 0 translation fault | user pgtable: 4k pages, 48-bit VAs, pgdp=0000000881cc8000 | [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 | Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP | CPU: 3 PID: 130 Comm: rmmod Not tainted 6.3.0-rc7 #6 | Hardware name: FVP Base RevC (DT) | pstate: 63402809 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=-c) | pc : 0x0 | lr : ffa_device_remove+0x20/0x2c | Call trace: | 0x0 | device_release_driver_internal+0x16c/0x260 | driver_detach+0x90/0xd0 | bus_remove_driver+0xdc/0x11c | driver_unregister+0x30/0x54 | ffa_driver_unregister+0x14/0x20 | cleanup_module+0x18/0xeec | __arm64_sys_delete_module+0x234/0x378 | invoke_syscall+0x40/0x108 | el0_svc_common+0xb4/0xf0 | do_el0_svc+0x30/0xa4 | el0_svc+0x2c/0x7c | el0t_64_sync_handler+0x84/0xf0 | el0t_64_sync+0x190/0x194 Fixes: 244f5d597e1e ("firmware: arm_ffa: Add missing remove callback to ffa_bus_type") Link: https://lore.kernel.org/r/20230419-ffa_fixes_6-4-v2-1-d9108e43a176@arm.com Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.