[PATCH v3 03/10] powerpc/rtas: Serialize firmware activation sequences

[Nathan Lynch via B4 Relay]

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.

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 579a2c475bb6..864d140e7247 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1738,10 +1738,14 @@ 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