[PATCH] riscv: ftrace: no need to acquire text_mutex when executed in stop_machine

[Steven Rostedt]

On Thu, 10 Mar 2022 12:54:54 +0800
Changbin Du <changbin.du at gmail.com> wrote:

> It's safe to patch text segment in stop_machine. No race is possible here.
> Besides, there is a false positive for the lock assertion in
> patch_insn_write() since the lock is not held by cpu migration thread.
> 
> So we actually don't need our ftrace_arch_code_modify_prepare/post(). And
> the lock assertion in patch_insn_write() should be removed to avoid
> producing lots of false positive warnings.
> 
> Signed-off-by: Changbin Du <changbin.du at gmail.com>

Ideally, RISC-V should try to get off of the stop_machine approach, and
move to the breakpoint modification.

-- Steve