[src/trunk]: src/sys/dev/acpi acpiec(4): Fix cv_wait loop around sc->sc_got_sci.

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/b91378fb2eb5
branches:  trunk
changeset: 377585:b91378fb2eb5
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Tue Jul 18 10:04:28 2023 +0000

description:
acpiec(4): Fix cv_wait loop around sc->sc_got_sci.

That is, make it actually loop as required, so it gracefully handles
spurious wakeups instead of barging into invalid states.

diffstat:

 sys/dev/acpi/acpi_ec.c |  9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diffs (39 lines):

diff -r 4eae614f639e -r b91378fb2eb5 sys/dev/acpi/acpi_ec.c
--- a/sys/dev/acpi/acpi_ec.c    Tue Jul 18 10:04:14 2023 +0000
+++ b/sys/dev/acpi/acpi_ec.c    Tue Jul 18 10:04:28 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: acpi_ec.c,v 1.92 2023/07/18 10:04:14 riastradh Exp $   */
+/*     $NetBSD: acpi_ec.c,v 1.93 2023/07/18 10:04:28 riastradh Exp $   */
 
 /*-
  * Copyright (c) 2007 Joerg Sonnenberger <joerg%NetBSD.org@localhost>.
@@ -57,7 +57,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi_ec.c,v 1.92 2023/07/18 10:04:14 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi_ec.c,v 1.93 2023/07/18 10:04:28 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_acpi_ec.h"
@@ -885,11 +885,9 @@ acpiec_gpe_query(void *arg)
 loop:
        /*
         * Wait until the EC sends an SCI requesting a query.
-        *
-        * XXX This needs to be `while', not `if'.
         */
        mutex_enter(&sc->sc_mtx);
-       if (sc->sc_got_sci == false)
+       while (!sc->sc_got_sci)
                cv_wait(&sc->sc_cv_sci, &sc->sc_mtx);
        DPRINTF(ACPIEC_DEBUG_QUERY, sc, "SCI query requested\n");
        mutex_exit(&sc->sc_mtx);
@@ -906,6 +904,7 @@ loop:
        KASSERT(sc->sc_state == EC_STATE_FREE);
 
        /* The Query command can always be issued, so be defensive here. */
+       KASSERT(sc->sc_got_sci);
        sc->sc_got_sci = false;
        sc->sc_state = EC_STATE_QUERY;