Commit 8608f14b authored by Rohan McLure's avatar Rohan McLure Committed by Michael Ellerman
Browse files

powerpc: Annotate accesses to ipi message flags 



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. Mark write for message source in
smp_muxed_ipi_set_message().

Signed-off-by: default avatarRohan McLure <rmclure@linux.ibm.com>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230510033117.1395895-8-rmclure@linux.ibm.com
parent b0c5b4f1

arch/powerpc/kernel/smp.c

+2 −2
Original line number Diff line number Diff line
@@ -291,7 +291,7 @@ void smp_muxed_ipi_set_message(int cpu, int msg) 
	 * Order previous accesses before accesses in the IPI handler.

	 */

	smp_mb();

	message[msg] = 1;

	WRITE_ONCE(message[msg], 1);

}



void smp_muxed_ipi_message_pass(int cpu, int msg)
@@ -350,7 +350,7 @@ 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;

}