Michael Ellerman <m...@ellerman.id.au> writes: > Nathan Lynch via B4 Relay <devnull+nathanl.linux.ibm....@kernel.org> > writes: >> From: Nathan Lynch <nath...@linux.ibm.com> >> >> On RTAS platforms there is a general restriction that the OS must not >> enter RTAS on more than one CPU at a time. This low-level >> serialization requirement is satisfied by holding a spin >> lock (rtas_lock) across most RTAS function invocations. > ... >> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c >> index 1fc0b3fffdd1..52f2242d0c28 100644 >> --- a/arch/powerpc/kernel/rtas.c >> +++ b/arch/powerpc/kernel/rtas.c >> @@ -581,6 +652,28 @@ static const struct rtas_function >> *rtas_token_to_function(s32 token) >> return NULL; >> } >> >> +static void __rtas_function_lock(struct rtas_function *func) >> +{ >> + if (func && func->lock) >> + mutex_lock(func->lock); >> +} > > This is obviously going to defeat most static analysis tools.
I guess it's not that obvious to me :-) Is it because the mutex_lock() is conditional? I'll improve this if it's possible. > I assume lockdep is OK with it though? Seems to be, yes.