Subject: [PATCH 08/12] powerpc: Annotate accesses to ipi message flags

From: Rohan McLure <[email-masked]>
Date: Mon, 8 May 2023 12:01:16 +1000

IPI message flags are observed and consequently consumed in the
smp_ipi_demux_relaxed function, which handles these message sources
until it observes none more arriving. Mark the checked loop guard with
READ_ONCE, to signal to KCSAN that the read is known to be volatile, and
that non-determinism is expected.

Signed-off-by: Rohan McLure <[email-masked]>
---
 arch/powerpc/kernel/smp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 6b90f10a6c81..00b74d66b771 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -348,7 +348,7 @@ irqreturn_t smp_ipi_demux_relaxed(void)
 		if (all & IPI_MESSAGE(PPC_MSG_NMI_IPI))
 			nmi_ipi_action(0, NULL);
 #endif
-	} while (info->messages);
+	} while (READ_ONCE(info->messages));
 
 	return IRQ_HANDLED;
 }
-- 
2.37.2