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Properly handle races between open/close and orphan.

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KASSERT the race between close and strategy, it is an error in the upper
echelons if this happens,

Add XXX: comment explaining why the ioctl/orphan race is not closed.
This commit is contained in:
Poul-Henning Kamp 2003-04-02 13:09:50 +00:00
parent b539f9d523
commit c7e1925c7c
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=112978
1 changed files with 34 additions and 10 deletions
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44
sys/geom/geom_dev.c
View file

@ -184,12 +184,11 @@ g_dev_open(dev_t dev, int flags, int fmt, struct thread *td)
gp = dev->si_drv1;
cp = dev->si_drv2;
if (gp == NULL || cp == NULL)
return(ENXIO);
if (gp == NULL || cp == NULL || gp->softc != dev)
return(ENXIO); /* g_dev_taste() not done yet */
g_trace(G_T_ACCESS, "g_dev_open(%s, %d, %d, %p)",
gp->name, flags, fmt, td);
DROP_GIANT();
g_topology_lock();
r = flags & FREAD ? 1 : 0;
w = flags & FWRITE ? 1 : 0;
#ifdef notyet
@ -197,11 +196,17 @@ g_dev_open(dev_t dev, int flags, int fmt, struct thread *td)
#else
e = 0;
#endif
error = g_access_rel(cp, r, w, e);
DROP_GIANT();
g_topology_lock();
if (dev->si_devsw == NULL)
error = ENXIO; /* We were orphaned */
else
error = g_access_rel(cp, r, w, e);
g_topology_unlock();
PICKUP_GIANT();
g_waitidle();
dev->si_bsize_phys = cp->provider->sectorsize;
if (!error)
dev->si_bsize_phys = cp->provider->sectorsize;
return(error);
}
@ -218,8 +223,6 @@ g_dev_close(dev_t dev, int flags, int fmt, struct thread *td)
return(ENXIO);
g_trace(G_T_ACCESS, "g_dev_close(%s, %d, %d, %p)",
gp->name, flags, fmt, td);
DROP_GIANT();
g_topology_lock();
r = flags & FREAD ? -1 : 0;
w = flags & FWRITE ? -1 : 0;
#ifdef notyet
@ -227,13 +230,26 @@ g_dev_close(dev_t dev, int flags, int fmt, struct thread *td)
#else
e = 0;
#endif
error = g_access_rel(cp, r, w, e);
DROP_GIANT();
g_topology_lock();
if (dev->si_devsw == NULL)
error = ENXIO; /* We were orphaned */
else
error = g_access_rel(cp, r, w, e);
KASSERT((cp->acr || cp->acw) || (cp->nstart == cp->nend),
("final g_dev_close() with outstanding bios"));
g_topology_unlock();
PICKUP_GIANT();
g_waitidle();
return (error);
}
/*
* XXX: Until we have unmessed the ioctl situation, there is a race against
* XXX: a concurrent orphanization. We cannot close it by holding topology
* XXX: since that would prevent us from doing our job, and stalling events
* XXX: will break (actually: stall) the BSD disklabel hacks.
*/
static int
g_dev_ioctl(dev_t dev, u_long cmd, caddr_t data, int fflag, struct thread *td)
{
@ -252,6 +268,8 @@ g_dev_ioctl(dev_t dev, u_long cmd, caddr_t data, int fflag, struct thread *td)
gio = NULL;
error = 0;
KASSERT(cp->acr || cp->acw,
("Consumer with zero access count in g_dev_ioctl"));
DROP_GIANT();
gio = NULL;
@ -377,6 +395,9 @@ g_dev_strategy(struct bio *bp)
dev = bp->bio_dev;
gp = dev->si_drv1;
cp = dev->si_drv2;
KASSERT(cp->acr || cp->acw,
("Consumer with zero access count in g_dev_strategy"));
bp2 = g_clone_bio(bp);
KASSERT(bp2 != NULL, ("XXX: ENOMEM in a bad place"));
bp2->bio_offset = (off_t)bp->bio_blkno << DEV_BSHIFT;
@ -390,6 +411,9 @@ g_dev_strategy(struct bio *bp)
bp, bp2, (intmax_t)bp->bio_offset, (intmax_t)bp2->bio_length,
bp2->bio_data, bp2->bio_cmd);
g_io_request(bp2, cp);
KASSERT(cp->acr || cp->acw,
("g_dev_strategy raced with g_dev_close and lost"));
}
/*
@ -425,7 +449,7 @@ g_dev_orphan(struct g_consumer *cp)
/* Wait for the cows to come home */
while (cp->nstart != cp->nend)
msleep(&dev, NULL, PRIBIO, "gdevorphan", 1);
msleep(&dev, NULL, PRIBIO, "gdevorphan", hz / 10);
if (cp->acr > 0 || cp->acw > 0 || cp->ace > 0)
g_access_rel(cp, -cp->acr, -cp->acw, -cp->ace);