[PATCH 11/12] powerpc: powernv: Annotate asynchronous access to opal tokens

[Rohan McLure]

The opal-async.c unit contains code for polling event sources, which
implies intentional data races. Ensure that the compiler will atomically
access such variables by means of {READ,WRITE}_ONCE calls, which in turn
inform KCSAN that polling behaviour is intended.

Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/opal-async.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal-async.c 
b/arch/powerpc/platforms/powernv/opal-async.c
index c094fdf5825c..282d2ac6fbb0 100644
--- a/arch/powerpc/platforms/powernv/opal-async.c
+++ b/arch/powerpc/platforms/powernv/opal-async.c
@@ -146,7 +146,7 @@ int opal_async_wait_response(uint64_t token, struct 
opal_msg *msg)
         * functional.
         */
        opal_wake_poller();
-       wait_event(opal_async_wait, opal_async_tokens[token].state
+       wait_event(opal_async_wait, READ_ONCE(opal_async_tokens[token].state)
                        == ASYNC_TOKEN_COMPLETED);
        memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
 
@@ -185,7 +185,7 @@ int opal_async_wait_response_interruptible(uint64_t token, 
struct opal_msg *msg)
         * interruptible version before doing anything else with the
         * token.
         */
-       if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED) {
+       if (READ_ONCE(opal_async_tokens[token].state) == ASYNC_TOKEN_ALLOCATED) 
{
                spin_lock_irqsave(&opal_async_comp_lock, flags);
                if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED)
                        opal_async_tokens[token].state = ASYNC_TOKEN_DISPATCHED;
@@ -199,7 +199,7 @@ int opal_async_wait_response_interruptible(uint64_t token, 
struct opal_msg *msg)
         */
        opal_wake_poller();
        ret = wait_event_interruptible(opal_async_wait,
-                       opal_async_tokens[token].state ==
+                       READ_ONCE(opal_async_tokens[token].state) ==
                        ASYNC_TOKEN_COMPLETED);
        if (!ret)
                memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
-- 
2.37.2