Re: [PATCH v4 05/13] powerpc/rtas: Facilitate high-level call sequences
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2023-11-28 22:31:39
Nathan Lynch via B4 Relay [off-list ref] writes:
From: Nathan Lynch <redacted> 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.
...
quoted hunk ↗ jump to hunk
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 assume lockdep is OK with it though? cheers