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.
This commit is contained in:
riastradh
parent
47e570fcd6
commit
fffd8cfe29
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@ -1,4 +1,4 @@
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/* $NetBSD: subr_autoconf.c,v 1.282 2021/06/12 12:12:11 riastradh Exp $ */
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/* $NetBSD: subr_autoconf.c,v 1.283 2021/06/12 12:13:51 riastradh Exp $ */
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/*
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* Copyright (c) 1996, 2000 Christopher G. Demetriou
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@ -79,7 +79,7 @@
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#define __SUBR_AUTOCONF_PRIVATE /* see <sys/device.h> */
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.282 2021/06/12 12:12:11 riastradh Exp $");
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__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.283 2021/06/12 12:13:51 riastradh Exp $");
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#ifdef _KERNEL_OPT
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#include "opt_ddb.h"
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@ -471,7 +471,6 @@ config_interrupts_thread(void *cookie)
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kmem_free(dc, sizeof(*dc));
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mutex_enter(&config_misc_lock);
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dev->dv_flags &= ~DVF_ATTACH_INPROGRESS;
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}
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mutex_exit(&config_misc_lock);
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@ -1721,6 +1720,7 @@ config_vattach(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
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device_t dev;
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struct cftable *ct;
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const char *drvname;
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bool deferred;
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KASSERT(KERNEL_LOCKED_P());
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@ -1776,10 +1776,15 @@ config_vattach(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
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/* Let userland know */
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devmon_report_device(dev, true);
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config_pending_incr(dev);
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(*dev->dv_cfattach->ca_attach)(parent, dev, aux);
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config_pending_decr(dev);
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if (((dev->dv_flags & DVF_ATTACH_INPROGRESS) == 0)
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&& !device_pmf_is_registered(dev))
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mutex_enter(&config_misc_lock);
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deferred = (dev->dv_pending != 0);
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mutex_exit(&config_misc_lock);
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if (!deferred && !device_pmf_is_registered(dev))
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aprint_debug_dev(dev,
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"WARNING: power management not supported\n");
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@ -1841,7 +1846,9 @@ config_attach_pseudo(cfdata_t cf)
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/* Let userland know */
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devmon_report_device(dev, true);
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config_pending_incr(dev);
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(*dev->dv_cfattach->ca_attach)(ROOT, dev, NULL);
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config_pending_decr(dev);
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config_process_deferred(&deferred_config_queue, dev);
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return dev;
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@ -1884,6 +1891,41 @@ config_dump_garbage(struct devicelist *garbage)
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}
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}
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static int
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config_detach_enter(device_t dev)
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{
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int error;
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mutex_enter(&config_misc_lock);
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for (;;) {
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if (dev->dv_pending == 0 && dev->dv_detaching == NULL) {
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dev->dv_detaching = curlwp;
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error = 0;
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break;
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}
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KASSERTMSG(dev->dv_detaching != curlwp,
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"recursively detaching %s", device_xname(dev));
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error = cv_wait_sig(&config_misc_cv, &config_misc_lock);
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if (error)
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break;
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}
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KASSERT(error || dev->dv_detaching == curlwp);
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mutex_exit(&config_misc_lock);
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return error;
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}
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static void
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config_detach_exit(device_t dev)
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{
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mutex_enter(&config_misc_lock);
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KASSERT(dev->dv_detaching == curlwp);
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dev->dv_detaching = NULL;
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cv_broadcast(&config_misc_cv);
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mutex_exit(&config_misc_lock);
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}
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/*
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* Detach a device. Optionally forced (e.g. because of hardware
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* removal) and quiet. Returns zero if successful, non-zero
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@ -1918,6 +1960,14 @@ config_detach(device_t dev, int flags)
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ca = dev->dv_cfattach;
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KASSERT(ca != NULL);
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/*
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* Only one detach at a time, please -- and not until fully
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* attached.
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*/
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rv = config_detach_enter(dev);
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if (rv)
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return rv;
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mutex_enter(&alldevs_lock);
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if (dev->dv_del_gen != 0) {
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mutex_exit(&alldevs_lock);
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@ -1925,6 +1975,7 @@ config_detach(device_t dev, int flags)
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printf("%s: %s is already detached\n", __func__,
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device_xname(dev));
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#endif /* DIAGNOSTIC */
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config_detach_exit(dev);
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return ENOENT;
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}
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alldevs_nwrite++;
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@ -2004,6 +2055,8 @@ config_detach(device_t dev, int flags)
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aprint_normal_dev(dev, "detached\n");
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out:
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config_detach_exit(dev);
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config_alldevs_enter(&af);
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KASSERT(alldevs_nwrite != 0);
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--alldevs_nwrite;
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@ -2204,7 +2257,6 @@ config_interrupts(device_t dev, void (*func)(device_t))
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dc->dc_dev = dev;
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dc->dc_func = func;
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TAILQ_INSERT_TAIL(&interrupt_config_queue, dc, dc_queue);
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dev->dv_flags |= DVF_ATTACH_INPROGRESS;
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mutex_exit(&config_misc_lock);
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}
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@ -2298,13 +2350,13 @@ config_pending_decr(device_t dev)
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mutex_enter(&config_misc_lock);
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KASSERTMSG(dev->dv_pending > 0,
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"%s: excess config_pending_decr", device_xname(dev));
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if (--dev->dv_pending == 0)
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if (--dev->dv_pending == 0) {
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TAILQ_REMOVE(&config_pending, dev, dv_pending_list);
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cv_broadcast(&config_misc_cv);
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}
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#ifdef DEBUG_AUTOCONF
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printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
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#endif
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if (TAILQ_EMPTY(&config_pending))
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cv_broadcast(&config_misc_cv);
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mutex_exit(&config_misc_lock);
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}
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@ -1,4 +1,4 @@
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/* $NetBSD: device.h,v 1.170 2021/05/10 13:59:30 thorpej Exp $ */
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/* $NetBSD: device.h,v 1.171 2021/06/12 12:13:51 riastradh Exp $ */
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/*
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* Copyright (c) 2021 The NetBSD Foundation, Inc.
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@ -274,6 +274,8 @@ struct device {
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int dv_pending; /* config_pending count */
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TAILQ_ENTRY(device) dv_pending_list;
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struct lwp *dv_detaching; /* detach lock (config_misc_lock/cv) */
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size_t dv_activity_count;
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void (**dv_activity_handlers)(device_t, devactive_t);
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