linux-kernel - [PATCH 2/6] powerpc/secvar: WARN_ON_ONCE() if multiple secvar ops are set

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Message-Id: <20221228072943.429266-3-ruscur@russell.cc>
Date:   Wed, 28 Dec 2022 18:29:39 +1100
From:   Russell Currey <ruscur@...sell.cc>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     gregkh@...uxfoundation.org, gcwilson@...ux.ibm.com,
        linux-kernel@...r.kernel.org, nayna@...ux.ibm.com,
        ajd@...ux.ibm.com, zohar@...ux.ibm.com, mpe@...erman.id.au,
        Russell Currey <ruscur@...sell.cc>
Subject: [PATCH 2/6] powerpc/secvar: WARN_ON_ONCE() if multiple secvar ops are set

The secvar code only supports one consumer at a time.

Multiple consumers aren't possible at this point in time, but we'd want
it to be obvious if it ever could happen.

Signed-off-by: Russell Currey <ruscur@...sell.cc>
---
 arch/powerpc/kernel/secvar-ops.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/secvar-ops.c b/arch/powerpc/kernel/secvar-ops.c
index 6a29777d6a2d..aa1b2adc2710 100644
--- a/arch/powerpc/kernel/secvar-ops.c
+++ b/arch/powerpc/kernel/secvar-ops.c
@@ -8,10 +8,12 @@
 
 #include <linux/cache.h>
 #include <asm/secvar.h>
+#include <asm/bug.h>
 
-const struct secvar_operations *secvar_ops __ro_after_init;
+const struct secvar_operations *secvar_ops __ro_after_init = NULL;
 
 void set_secvar_ops(const struct secvar_operations *ops)
 {
+	WARN_ON_ONCE(secvar_ops);
 	secvar_ops = ops;
 }
-- 
2.38.1