Nathan Lynch via B4 Relay <devnull+nathanl.linux.ibm....@kernel.org>
writes:
> From: Nathan Lynch <nath...@linux.ibm.com>
>
> Use the function lock API to prevent interleaving call sequences of
> the ibm,activate-firmware RTAS function, which typically requires
> multiple calls to complete the update. While the spec does not
> specifically prohibit interleaved sequences, there's almost certainly
> no advantage to allowing them.
>
Can we document what is the equivalent thing the userspace does?
Reviewed-by: Aneesh Kumar K.V (IBM) <aneesh.ku...@kernel.org>
> Signed-off-by: Nathan Lynch <nath...@linux.ibm.com>
> ---
> arch/powerpc/kernel/rtas.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
> index 52f2242d0c28..e38ba05ad613 100644
> --- a/arch/powerpc/kernel/rtas.c
> +++ b/arch/powerpc/kernel/rtas.c
> @@ -1753,10 +1753,14 @@ void rtas_activate_firmware(void)
> return;
> }
>
> + rtas_function_lock(RTAS_FN_IBM_ACTIVATE_FIRMWARE);
> +
> do {
> fwrc = rtas_call(token, 0, 1, NULL);
> } while (rtas_busy_delay(fwrc));
>
> + rtas_function_unlock(RTAS_FN_IBM_ACTIVATE_FIRMWARE);
> +
> if (fwrc)
> pr_err("ibm,activate-firmware failed (%i)\n", fwrc);
> }
>
> --
> 2.41.0
