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g_mirror_taste: avoid deadlock, always clear tasting flag

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If g_mirror_taste encountered an error at g_mirror_add_disk, it might
try to g_mirror_destroy the device with the G_MIRROR_DEVICE_FLAG_TASTING
flag still set.  This would wait on a worker to complete the destruction
with g_mirror_try_destroy, but that function bails out if the tasting
flag is set, resulting in a deadlock.  Clear the tasting flag before
trying to destroy the device.

Test Plan:
sysctl debug.fail_point.mnowait="1%return"
kyua test -k /usr/tests/sys/geom/class/mirror/Kyuafile

Reviewed by:	markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D20744
This commit is contained in:
Ryan Libby 2019-07-01 22:06:36 +00:00
parent 3bb6e0f0c7
commit 9167705c8c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=349587
1 changed files with 1 additions and 1 deletions
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2
sys/geom/mirror/g_mirror.c
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@ -3291,6 +3291,7 @@ g_mirror_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
sx_xlock(&sc->sc_lock);
sc->sc_flags |= G_MIRROR_DEVICE_FLAG_TASTING;
error = g_mirror_add_disk(sc, pp, &md);
sc->sc_flags &= ~G_MIRROR_DEVICE_FLAG_TASTING;
if (error != 0) {
G_MIRROR_DEBUG(0, "Cannot add disk %s to %s (error=%d).",
pp->name, gp->name, error);
@ -3302,7 +3303,6 @@ g_mirror_taste(struct g_class *mp, struct g_provider *pp, int flags __unused)
}
gp = NULL;
}
sc->sc_flags &= ~G_MIRROR_DEVICE_FLAG_TASTING;
if ((sc->sc_flags & G_MIRROR_DEVICE_FLAG_DESTROY) != 0) {
g_mirror_destroy(sc, G_MIRROR_DESTROY_HARD);
g_topology_lock();