Author: mav
Date: Tue Dec 3 17:06:48 2019
New Revision: 355342
URL: https://svnweb.freebsd.org/changeset/base/355342
Log:
MFC r354986: Add variant of root_mount_hold() without allocation.
It allows to use this KPI in non-sleepable contexts.
Modified:
stable/12/sys/kern/vfs_mountroot.c
stable/12/sys/sys/systm.h
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/kern/vfs_mountroot.c
==============================================================================
--- stable/12/sys/kern/vfs_mountroot.c Tue Dec 3 16:52:39 2019
(r355341)
+++ stable/12/sys/kern/vfs_mountroot.c Tue Dec 3 17:06:48 2019
(r355342)
@@ -110,14 +110,9 @@ char *rootdevnames[2] = {NULL, NULL};
struct mtx root_holds_mtx;
MTX_SYSINIT(root_holds, &root_holds_mtx, "root_holds", MTX_DEF);
-struct root_hold_token {
- const char *who;
- LIST_ENTRY(root_hold_token) list;
-};
+static TAILQ_HEAD(, root_hold_token) root_holds =
+ TAILQ_HEAD_INITIALIZER(root_holds);
-static LIST_HEAD(, root_hold_token) root_holds =
- LIST_HEAD_INITIALIZER(root_holds);
-
enum action {
A_CONTINUE,
A_PANIC,
@@ -125,6 +120,12 @@ enum action {
A_RETRY
};
+enum rh_flags {
+ RH_FREE,
+ RH_ALLOC,
+ RH_ARG,
+};
+
static enum action root_mount_onfail = A_CONTINUE;
static int root_mount_mddev;
@@ -154,8 +155,8 @@ sysctl_vfs_root_mount_hold(SYSCTL_HANDLER_ARGS)
sbuf_new(&sb, NULL, 256, SBUF_AUTOEXTEND | SBUF_INCLUDENUL);
mtx_lock(&root_holds_mtx);
- LIST_FOREACH(h, &root_holds, list) {
- if (h != LIST_FIRST(&root_holds))
+ TAILQ_FOREACH(h, &root_holds, list) {
+ if (h != TAILQ_FIRST(&root_holds))
sbuf_putc(&sb, ' ');
sbuf_printf(&sb, "%s", h->who);
}
@@ -174,27 +175,54 @@ root_mount_hold(const char *identifier)
struct root_hold_token *h;
h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
+ h->flags = RH_ALLOC;
h->who = identifier;
mtx_lock(&root_holds_mtx);
TSHOLD("root mount");
- LIST_INSERT_HEAD(&root_holds, h, list);
+ TAILQ_INSERT_TAIL(&root_holds, h, list);
mtx_unlock(&root_holds_mtx);
return (h);
}
void
+root_mount_hold_token(const char *identifier, struct root_hold_token *h)
+{
+#ifdef INVARIANTS
+ struct root_hold_token *t;
+#endif
+
+ h->flags = RH_ARG;
+ h->who = identifier;
+ mtx_lock(&root_holds_mtx);
+#ifdef INVARIANTS
+ TAILQ_FOREACH(t, &root_holds, list) {
+ if (t == h) {
+ panic("Duplicate mount hold by '%s' on %p",
+ identifier, h);
+ }
+ }
+#endif
+ TSHOLD("root mount");
+ TAILQ_INSERT_TAIL(&root_holds, h, list);
+ mtx_unlock(&root_holds_mtx);
+}
+
+void
root_mount_rel(struct root_hold_token *h)
{
- if (h == NULL)
+ if (h == NULL || h->flags == RH_FREE)
return;
mtx_lock(&root_holds_mtx);
- LIST_REMOVE(h, list);
+ TAILQ_REMOVE(&root_holds, h, list);
TSRELEASE("root mount");
wakeup(&root_holds);
mtx_unlock(&root_holds_mtx);
- free(h, M_DEVBUF);
+ if (h->flags == RH_ALLOC) {
+ free(h, M_DEVBUF);
+ } else
+ h->flags = RH_FREE;
}
int
@@ -961,13 +989,13 @@ vfs_mountroot_wait(void)
while (1) {
g_waitidle();
mtx_lock(&root_holds_mtx);
- if (LIST_EMPTY(&root_holds)) {
+ if (TAILQ_EMPTY(&root_holds)) {
mtx_unlock(&root_holds_mtx);
break;
}
if (ppsratecheck(&lastfail, &curfail, 1)) {
printf("Root mount waiting for:");
- LIST_FOREACH(h, &root_holds, list)
+ TAILQ_FOREACH(h, &root_holds, list)
printf(" %s", h->who);
printf("\n");
}
Modified: stable/12/sys/sys/systm.h
==============================================================================
--- stable/12/sys/sys/systm.h Tue Dec 3 16:52:39 2019 (r355341)
+++ stable/12/sys/sys/systm.h Tue Dec 3 17:06:48 2019 (r355342)
@@ -503,9 +503,14 @@ int poll_no_poll(int events);
void DELAY(int usec);
/* Root mount holdback API */
-struct root_hold_token;
+struct root_hold_token {
+ int flags;
+ const char *who;
+ TAILQ_ENTRY(root_hold_token) list;
+};
struct root_hold_token *root_mount_hold(const char *identifier);
+void root_mount_hold_token(const char *identifier, struct root_hold_token *h);
void root_mount_rel(struct root_hold_token *h);
int root_mounted(void);
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