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Code Issues Releases Activity

Add a named reference-count KPI to hold off mounting of the root filesystem.

Browse Source 
While we wait for holds to be released, print a list of who holds us
back once per second.

Use the new KPI from GEOM instead of vfs_mount.c calling g_waitidle().

Use the new KPI also from ata.

With ATAmkIII's newbusification, ata could narrowly miss the window
and ad0 would not exist when we tried to mount root.
This commit is contained in:
Poul-Henning Kamp 2005-04-18 21:21:26 +00:00
parent bdb3564638
commit 73fbaa74e5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=145250
4 changed files with 65 additions and 6 deletions
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3
sys/dev/ata/ata-all.c
View File

@ -81,6 +81,7 @@ int ata_wc = 1;
/* local vars */
static struct intr_config_hook *ata_delayed_attach = NULL;
static struct root_hold_token *ata_root_hold_token;
static int ata_dma = 1;
static int atapi_dma = 1;
@ -559,6 +560,7 @@ ata_boot_attach(void)
ata_identify(ch->dev);
}
}
root_mount_rel(ata_root_hold_token);
}
/*
@ -814,6 +816,7 @@ ata_module_event_handler(module_t mod, int what, void *arg)
return EIO;
}
ata_delayed_attach->ich_func = (void*)ata_boot_attach;
ata_root_hold_token = root_mount_hold("ATA");
if (config_intrhook_establish(ata_delayed_attach) != 0) {
printf("ata: config_intrhook_establish failed\n");
free(ata_delayed_attach, M_TEMP);

6
sys/geom/geom_kern.c
View File

@ -132,13 +132,19 @@ g_event_procbody(void)
{
struct proc *p = g_event_proc;
struct thread *tp = FIRST_THREAD_IN_PROC(p);
struct root_hold_token *t;
mtx_assert(&Giant, MA_NOTOWNED);
mtx_lock_spin(&sched_lock);
sched_prio(tp, PRIBIO);
mtx_unlock_spin(&sched_lock);
t = root_mount_hold("GEOM");
for(;;) {
g_run_events();
if (t != 0) {
root_mount_rel(t);
t = NULL;
}
tsleep(&g_wait_event, PRIBIO, "-", hz/10);
}
}

55
sys/kern/vfs_mount.c
View File

@ -1004,6 +1004,54 @@ dounmount(mp, flags, td)
*
*/
struct root_hold_token {
const char *who;
LIST_ENTRY(root_hold_token) list;
};
static LIST_HEAD(, root_hold_token) root_holds =
LIST_HEAD_INITIALIZER(&root_holds);
struct root_hold_token *
root_mount_hold(const char *identifier)
{
struct root_hold_token *h;
h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
h->who = identifier;
mtx_lock(&mountlist_mtx);
LIST_INSERT_HEAD(&root_holds, h, list);
mtx_unlock(&mountlist_mtx);
return (h);
}
void
root_mount_rel(struct root_hold_token *h)
{
mtx_lock(&mountlist_mtx);
LIST_REMOVE(h, list);
wakeup(&root_holds);
mtx_unlock(&mountlist_mtx);
free(h, M_DEVBUF);
}
static void
root_mount_wait(void)
{
struct root_hold_token *h;
mtx_lock(&mountlist_mtx);
while (!LIST_EMPTY(&root_holds)) {
printf("Root mount waiting for:");
LIST_FOREACH(h, &root_holds, list)
printf(" %s", h->who);
printf("\n");
msleep(&root_holds, &mountlist_mtx, PZERO, "roothold", hz);
}
mtx_unlock(&mountlist_mtx);
}
static void
set_rootvnode(struct thread *td)
{
@ -1140,12 +1188,7 @@ vfs_mountroot(void)
int error, i, asked = 0;
struct mount *mp;
/*
* Wait for GEOM to settle down
*/
DROP_GIANT();
g_waitidle();
PICKUP_GIANT();
root_mount_wait();
mp = devfs_first();

7
sys/sys/systm.h
View File

@ -315,6 +315,13 @@ const char *devtoname(struct cdev *cdev);
/* XXX: Should be void nanodelay(u_int nsec); */
void DELAY(int usec);
/* Root mount holdback API */
struct root_hold_token;
struct root_hold_token *root_mount_hold(const char *identifier);
void root_mount_rel(struct root_hold_token *h);
/*
* Unit number allocation API. (kern/subr_unit.c)
*/