Module Name: src
Committed By: riastradh
Date: Sat Jun 12 12:13:51 UTC 2021
Modified Files:
src/sys/kern: subr_autoconf.c
src/sys/sys: device.h
Log Message:
autoconf(9): Prevent concurrent attach/detach and detach/detach.
- Use config_pending_incr/decr around attach. No need for separate
flag indicating device is still attaching. (dv_flags locking is also
incoherent.)
- Any config_pending now blocks config_detach.
- New dv_detaching exclusive lock for config_detach.
To generate a diff of this commit:
cvs rdiff -u -r1.282 -r1.283 src/sys/kern/subr_autoconf.c
cvs rdiff -u -r1.170 -r1.171 src/sys/sys/device.h
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/subr_autoconf.c
diff -u src/sys/kern/subr_autoconf.c:1.282 src/sys/kern/subr_autoconf.c:1.283
--- src/sys/kern/subr_autoconf.c:1.282 Sat Jun 12 12:12:11 2021
+++ src/sys/kern/subr_autoconf.c Sat Jun 12 12:13:51 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_autoconf.c,v 1.282 2021/06/12 12:12:11 riastradh Exp $ */
+/* $NetBSD: subr_autoconf.c,v 1.283 2021/06/12 12:13:51 riastradh Exp $ */
/*
* Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -79,7 +79,7 @@
#define __SUBR_AUTOCONF_PRIVATE /* see <sys/device.h> */
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.282 2021/06/12 12:12:11 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.283 2021/06/12 12:13:51 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -471,7 +471,6 @@ config_interrupts_thread(void *cookie)
kmem_free(dc, sizeof(*dc));
mutex_enter(&config_misc_lock);
- dev->dv_flags &= ~DVF_ATTACH_INPROGRESS;
}
mutex_exit(&config_misc_lock);
@@ -1721,6 +1720,7 @@ config_vattach(device_t parent, cfdata_t
device_t dev;
struct cftable *ct;
const char *drvname;
+ bool deferred;
KASSERT(KERNEL_LOCKED_P());
@@ -1776,10 +1776,15 @@ config_vattach(device_t parent, cfdata_t
/* Let userland know */
devmon_report_device(dev, true);
+ config_pending_incr(dev);
(*dev->dv_cfattach->ca_attach)(parent, dev, aux);
+ config_pending_decr(dev);
- if (((dev->dv_flags & DVF_ATTACH_INPROGRESS) == 0)
- && !device_pmf_is_registered(dev))
+ mutex_enter(&config_misc_lock);
+ deferred = (dev->dv_pending != 0);
+ mutex_exit(&config_misc_lock);
+
+ if (!deferred && !device_pmf_is_registered(dev))
aprint_debug_dev(dev,
"WARNING: power management not supported\n");
@@ -1841,7 +1846,9 @@ config_attach_pseudo(cfdata_t cf)
/* Let userland know */
devmon_report_device(dev, true);
+ config_pending_incr(dev);
(*dev->dv_cfattach->ca_attach)(ROOT, dev, NULL);
+ config_pending_decr(dev);
config_process_deferred(&deferred_config_queue, dev);
return dev;
@@ -1884,6 +1891,41 @@ config_dump_garbage(struct devicelist *g
}
}
+static int
+config_detach_enter(device_t dev)
+{
+ int error;
+
+ mutex_enter(&config_misc_lock);
+ for (;;) {
+ if (dev->dv_pending == 0 && dev->dv_detaching == NULL) {
+ dev->dv_detaching = curlwp;
+ error = 0;
+ break;
+ }
+ KASSERTMSG(dev->dv_detaching != curlwp,
+ "recursively detaching %s", device_xname(dev));
+ error = cv_wait_sig(&config_misc_cv, &config_misc_lock);
+ if (error)
+ break;
+ }
+ KASSERT(error || dev->dv_detaching == curlwp);
+ mutex_exit(&config_misc_lock);
+
+ return error;
+}
+
+static void
+config_detach_exit(device_t dev)
+{
+
+ mutex_enter(&config_misc_lock);
+ KASSERT(dev->dv_detaching == curlwp);
+ dev->dv_detaching = NULL;
+ cv_broadcast(&config_misc_cv);
+ mutex_exit(&config_misc_lock);
+}
+
/*
* Detach a device. Optionally forced (e.g. because of hardware
* removal) and quiet. Returns zero if successful, non-zero
@@ -1918,6 +1960,14 @@ config_detach(device_t dev, int flags)
ca = dev->dv_cfattach;
KASSERT(ca != NULL);
+ /*
+ * Only one detach at a time, please -- and not until fully
+ * attached.
+ */
+ rv = config_detach_enter(dev);
+ if (rv)
+ return rv;
+
mutex_enter(&alldevs_lock);
if (dev->dv_del_gen != 0) {
mutex_exit(&alldevs_lock);
@@ -1925,6 +1975,7 @@ config_detach(device_t dev, int flags)
printf("%s: %s is already detached\n", __func__,
device_xname(dev));
#endif /* DIAGNOSTIC */
+ config_detach_exit(dev);
return ENOENT;
}
alldevs_nwrite++;
@@ -2004,6 +2055,8 @@ config_detach(device_t dev, int flags)
aprint_normal_dev(dev, "detached\n");
out:
+ config_detach_exit(dev);
+
config_alldevs_enter(&af);
KASSERT(alldevs_nwrite != 0);
--alldevs_nwrite;
@@ -2204,7 +2257,6 @@ config_interrupts(device_t dev, void (*f
dc->dc_dev = dev;
dc->dc_func = func;
TAILQ_INSERT_TAIL(&interrupt_config_queue, dc, dc_queue);
- dev->dv_flags |= DVF_ATTACH_INPROGRESS;
mutex_exit(&config_misc_lock);
}
@@ -2298,13 +2350,13 @@ config_pending_decr(device_t dev)
mutex_enter(&config_misc_lock);
KASSERTMSG(dev->dv_pending > 0,
"%s: excess config_pending_decr", device_xname(dev));
- if (--dev->dv_pending == 0)
+ if (--dev->dv_pending == 0) {
TAILQ_REMOVE(&config_pending, dev, dv_pending_list);
+ cv_broadcast(&config_misc_cv);
+ }
#ifdef DEBUG_AUTOCONF
printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
#endif
- if (TAILQ_EMPTY(&config_pending))
- cv_broadcast(&config_misc_cv);
mutex_exit(&config_misc_lock);
}
Index: src/sys/sys/device.h
diff -u src/sys/sys/device.h:1.170 src/sys/sys/device.h:1.171
--- src/sys/sys/device.h:1.170 Mon May 10 13:59:30 2021
+++ src/sys/sys/device.h Sat Jun 12 12:13:51 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: device.h,v 1.170 2021/05/10 13:59:30 thorpej Exp $ */
+/* $NetBSD: device.h,v 1.171 2021/06/12 12:13:51 riastradh Exp $ */
/*
* Copyright (c) 2021 The NetBSD Foundation, Inc.
@@ -274,6 +274,8 @@ struct device {
int dv_pending; /* config_pending count */
TAILQ_ENTRY(device) dv_pending_list;
+ struct lwp *dv_detaching; /* detach lock (config_misc_lock/cv) */
+
size_t dv_activity_count;
void (**dv_activity_handlers)(device_t, devactive_t);
