Module Name: src
Committed By: riastradh
Date: Sat Jun 12 12:14:03 UTC 2021
Modified Files:
src/sys/kern: kern_drvctl.c
Log Message:
drvctl(4): Hold a deviter while issuing config_detach.
Otherwise another concurrent detach -- e.g., from concurrent drvctl
or from USB port disconnection -- can pull the device_t out from
under us.
XXX Need to do this for _every_ operation config_* operation on a
device_t; device_find_by_xname is just fundamentally broken because a
concurrent detach can pull the device_t rug out from under you.
We really need another mechanism for holding a weak reference to a
device, and temporarily getting a strong reference to it; abusing
deviter is a bit of a kludge, and doesn't work very well because it
doesn't properly trigger garbage collection of devices detached while
other concurrent deviters are pending.
To generate a diff of this commit:
cvs rdiff -u -r1.47 -r1.48 src/sys/kern/kern_drvctl.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_drvctl.c
diff -u src/sys/kern/kern_drvctl.c:1.47 src/sys/kern/kern_drvctl.c:1.48
--- src/sys/kern/kern_drvctl.c:1.47 Sat Jun 12 12:12:11 2021
+++ src/sys/kern/kern_drvctl.c Sat Jun 12 12:14:03 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_drvctl.c,v 1.47 2021/06/12 12:12:11 riastradh Exp $ */
+/* $NetBSD: kern_drvctl.c,v 1.48 2021/06/12 12:14:03 riastradh Exp $ */
/*
* Copyright (c) 2004
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_drvctl.c,v 1.47 2021/06/12 12:12:11 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_drvctl.c,v 1.48 2021/06/12 12:14:03 riastradh Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -254,11 +254,21 @@ static int
detachdevbyname(const char *devname)
{
device_t d;
+ deviter_t di;
+ int error;
KASSERT(KERNEL_LOCKED_P());
- if ((d = device_find_by_xname(devname)) == NULL)
- return ENXIO;
+ for (d = deviter_first(&di, DEVITER_F_RW);
+ d != NULL;
+ d = deviter_next(&di)) {
+ if (strcmp(device_xname(d), devname) == 0)
+ break;
+ }
+ if (d == NULL) {
+ error = ENXIO;
+ goto out;
+ }
#ifndef XXXFULLRISK
/*
@@ -267,10 +277,15 @@ detachdevbyname(const char *devname)
* There might be a private notification mechanism,
* but better play it safe here.
*/
- if (d->dv_parent && !d->dv_parent->dv_cfattach->ca_childdetached)
- return ENOTSUP;
+ if (d->dv_parent && !d->dv_parent->dv_cfattach->ca_childdetached) {
+ error = ENOTSUP;
+ goto out;
+ }
#endif
- return config_detach(d, 0);
+
+ error = config_detach(d, 0);
+out: deviter_release(&di);
+ return error;
}
static int
