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Try to close the race between disk_destroy() and a subsequent disk_create().

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This commit is contained in:
Poul-Henning Kamp 2003-09-01 12:03:13 +00:00
parent 7c78880561
commit ce1ee7895e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=119652
1 changed files with 17 additions and 19 deletions
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36
sys/geom/geom_disk.c
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@ -332,7 +332,16 @@ g_disk_create(void *arg, int flag)
g_error_provider(pp, 0);
}
static void
g_disk_destroy(void *ptr, int flag)
{
struct g_geom *gp;
g_topology_assert();
gp = ptr;
gp->softc = NULL;
g_wither_geom(gp, ENXIO);
}
void
disk_create(int unit, struct disk *dp, int flags, void *unused __unused, void * unused2 __unused)
@ -344,6 +353,9 @@ disk_create(int unit, struct disk *dp, int flags, void *unused __unused, void *
KASSERT(dp->d_name != NULL, ("disk_create need d_name"));
KASSERT(*dp->d_name != 0, ("disk_create need d_name"));
KASSERT(strlen(dp->d_name) < SPECNAMELEN - 4, ("disk name too long"));
if (bootverbose || 1)
printf("GEOM: create disk %s%d dp=%p\n",
dp->d_name, dp->d_unit, dp);
dp->d_devstat = devstat_new_entry(dp->d_name, dp->d_unit,
dp->d_sectorsize, DEVSTAT_ALL_SUPPORTED,
DEVSTAT_TYPE_DIRECT, DEVSTAT_PRIORITY_MAX);
@ -351,36 +363,22 @@ disk_create(int unit, struct disk *dp, int flags, void *unused __unused, void *
g_post_event(g_disk_create, dp, M_WAITOK, dp, NULL);
}
/*
* XXX: There is a race if disk_destroy() is called while the g_disk_create()
* XXX: event is running. I belive the current result is that disk_destroy()
* XXX: actually doesn't do anything. Considering that the driver owns the
* XXX: struct disk and is likely to free it in a few moments, this can
* XXX: hardly be said to be optimal. To what extent we can sleep in
* XXX: disk_create() and disk_destroy() is currently undefined (but generally
* XXX: undesirable) so any solution seems to involve an intrusive decision.
*/
static void
disk_destroy_event(void *ptr, int flag)
{
g_topology_assert();
g_wither_geom(ptr, ENXIO);
}
void
disk_destroy(struct disk *dp)
{
struct g_geom *gp;
if (bootverbose || 1)
printf("GEOM: destroy disk %s%d dp=%p\n",
dp->d_name, dp->d_unit, dp);
g_cancel_event(dp);
gp = dp->d_geom;
if (gp == NULL)
return;
gp->softc = NULL;
devstat_remove_entry(dp->d_devstat);
g_post_event(disk_destroy_event, gp, M_WAITOK, NULL, NULL);
g_waitfor_event(g_disk_destroy, gp, M_WAITOK, NULL, NULL);
dp->d_geom = NULL;
}
static void