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thinkpad(4): Don't detach on shutdown. 

There's no important state that needs to be recorded, or resources
that need to be relinquished, so detach-on-shutdown isn't necessary.

At the moment, detach-on-shutdown is actually harmful here: if
shutdown is triggered by a sysmon power switch event, then
config_detach will be called from the sysmon taskqueue, but
thinkpad_detach has to wait for ACPI notifiers to finish running
which means waiting for the sysmon taskqueue -> deadlock or crash.

We should maybe arrange to do config_detach from a thread other than
the sysmon taskqueue thread to avoid this class of problems -- but
for now, thinkpad(4) has no reason to detach on shutdown anyway, so
let's take the easy path.

Note: There are many drivers that set DVF_DETACH_SHUTDOWN which
probably shouldn't; the flag means the kernel _will_ detach on
shutdown, not that it _may_.  Even those that do need to record state
or relinquish resources might be better served by pmf shutdown hooks
which can skip freeing software resources for faster shutdown.
This commit is contained in:
riastradh 2022-08-12 16:21:41 +00:00
parent 1536c4bfa3
commit 8769a2203d
1 changed files with 3 additions and 3 deletions
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6
sys/dev/acpi/thinkpad_acpi.c
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@ -1,4 +1,4 @@
/* $NetBSD: thinkpad_acpi.c,v 1.54 2021/12/31 17:22:35 riastradh Exp $ */
/* $NetBSD: thinkpad_acpi.c,v 1.55 2022/08/12 16:21:41 riastradh Exp $ */
/*-
* Copyright (c) 2007 Jared D. McNeill <jmcneill@invisible.ca>
@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: thinkpad_acpi.c,v 1.54 2021/12/31 17:22:35 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: thinkpad_acpi.c,v 1.55 2022/08/12 16:21:41 riastradh Exp $");
#include <sys/param.h>
#include <sys/device.h>
@ -170,7 +170,7 @@ static void thinkpad_cmos(thinkpad_softc_t *, uint8_t);
CFATTACH_DECL3_NEW(thinkpad, sizeof(thinkpad_softc_t),
thinkpad_match, thinkpad_attach, thinkpad_detach, NULL, NULL, NULL,
DVF_DETACH_SHUTDOWN);
0);
static const struct device_compatible_entry compat_data[] = {
{ .compat = "IBM0068" },