diff options
| author | riastradh <riastradh@NetBSD.org> | 2021-09-07 10:43:51 +0000 |
|---|---|---|
| committer | riastradh <riastradh@NetBSD.org> | 2021-09-07 10:43:51 +0000 |
| commit | d4881043c9f48c669a072547cdccfbe0e667b6dc (patch) | |
| tree | d6597bb4efc50e640ba1b19e54444b0f417c8c24 /sys/dev | |
| parent | cdaa2b6287c7cd0aba59fe9650ce03ac9171c4b7 (diff) | |
ugen(4): Use cv_wait loop for draining reference count on detach.
- Should be no need to use cv_timedwait because all users have now
been given a wakeup (previously writers were not, so we relied on
the timeouts to work out).
- Need to run this in a loop or else a spurious wakeup could cause us
to free data structures before the users have actually drained.
Diffstat (limited to 'sys/dev')
| -rw-r--r-- | sys/dev/usb/ugen.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/sys/dev/usb/ugen.c b/sys/dev/usb/ugen.c index 894be8ec928..5f8bb44602b 100644 --- a/sys/dev/usb/ugen.c +++ b/sys/dev/usb/ugen.c @@ -1,4 +1,4 @@ -/* $NetBSD: ugen.c,v 1.165 2021/09/07 10:43:34 riastradh Exp $ */ +/* $NetBSD: ugen.c,v 1.166 2021/09/07 10:43:51 riastradh Exp $ */ /* * Copyright (c) 1998, 2004 The NetBSD Foundation, Inc. @@ -37,7 +37,7 @@ #include <sys/cdefs.h> -__KERNEL_RCSID(0, "$NetBSD: ugen.c,v 1.165 2021/09/07 10:43:34 riastradh Exp $"); +__KERNEL_RCSID(0, "$NetBSD: ugen.c,v 1.166 2021/09/07 10:43:51 riastradh Exp $"); #ifdef _KERNEL_OPT #include "opt_compat_netbsd.h" @@ -1215,6 +1215,12 @@ ugen_detach(device_t self, int flags) } } + /* + * Wait for users to drain. Before this point there can be no + * more I/O operations started because we set sc_dying; after + * this, there can be no more I/O operations in progress, so it + * will be safe to free things. + */ mutex_enter(&sc->sc_lock); if (--sc->sc_refcnt >= 0) { /* Wake everyone */ @@ -1223,8 +1229,9 @@ ugen_detach(device_t self, int flags) cv_broadcast(&sc->sc_endpoints[i][dir].cv); } /* Wait for processes to go away. */ - if (cv_timedwait(&sc->sc_detach_cv, &sc->sc_lock, hz * 60)) - aprint_error_dev(self, ": didn't detach\n"); + do { + cv_wait(&sc->sc_detach_cv, &sc->sc_lock); + } while (sc->sc_refcnt >= 0); } mutex_exit(&sc->sc_lock); |
