[src/trunk]: src/sys/dev/acpi acpibat(4): Fix race in detach with AcpiOsExecu...

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

details:   https://anonhg.NetBSD.org/src/rev/a7b6becfec73
branches:  trunk
changeset: 359453:a7b6becfec73
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Jan 07 01:10:57 2022 +0000

description:
acpibat(4): Fix race in detach with AcpiOsExecute deferred call.

diffstat:

 sys/dev/acpi/acpi_bat.c |  28 +++++++++++++++++++++++++---
 1 files changed, 25 insertions(+), 3 deletions(-)

diffs (76 lines):

diff -r a661907c72f6 -r a7b6becfec73 sys/dev/acpi/acpi_bat.c
--- a/sys/dev/acpi/acpi_bat.c   Fri Jan 07 01:03:02 2022 +0000
+++ b/sys/dev/acpi/acpi_bat.c   Fri Jan 07 01:10:57 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: acpi_bat.c,v 1.120 2021/12/31 14:20:56 riastradh Exp $ */
+/*     $NetBSD: acpi_bat.c,v 1.121 2022/01/07 01:10:57 riastradh Exp $ */
 
 /*-
  * Copyright (c) 2003 The NetBSD Foundation, Inc.
@@ -75,7 +75,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi_bat.c,v 1.120 2021/12/31 14:20:56 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi_bat.c,v 1.121 2022/01/07 01:10:57 riastradh Exp $");
 
 #include <sys/param.h>
 #include <sys/condvar.h>
@@ -157,6 +157,7 @@
        int32_t                  sc_lcapacity;
        int32_t                  sc_wcapacity;
        int                      sc_present;
+       bool                     sc_dying;
 };
 
 static const struct device_compatible_entry compat_data[] = {
@@ -262,12 +263,29 @@
 {
        struct acpibat_softc *sc = device_private(self);
 
+       /* Prevent further use of sc->sc_sme in acpibat_update_info.  */
+       mutex_enter(&sc->sc_mutex);
+       sc->sc_dying = true;
+       mutex_exit(&sc->sc_mutex);
+
+       /* Prevent further calls to acpibat_resume.  */
        pmf_device_deregister(self);
+
+       /* Prevent further calls to acpibat_notify_handler.  */
        acpi_deregister_notify(sc->sc_node);
 
+       /* Detach sensors and prevent further calls to acpibat_refresh. */
        if (sc->sc_sme != NULL)
                sysmon_envsys_unregister(sc->sc_sme);
 
+       /*
+        * Wait for calls to acpibat_update_info/status in case sysmon
+        * envsys refreshed the sensors and queued them but they didn't
+        * run before sysmon_envsys_unregister.  After this point, no
+        * asynchronous access to the softc is possible.
+        */
+       AcpiOsWaitEventsComplete();
+
        if (sc->sc_sensor != NULL)
                kmem_free(sc->sc_sensor, ACPIBAT_COUNT *
                    sizeof(*sc->sc_sensor));
@@ -599,6 +617,10 @@
 
        mutex_enter(&sc->sc_mutex);
 
+       /* Don't touch sc_sme if we're detaching.  */
+       if (sc->sc_dying)
+               goto out;
+
        rv = acpibat_get_sta(dv);
        if (rv > 0) {
                acpibat_get_info(dv);
@@ -619,7 +641,7 @@
        }
 
        sc->sc_present = rv;
-
+out:
        mutex_exit(&sc->sc_mutex);
 }