1 files changed, 373 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/os/freebsd/spl/callb.c b/sys/contrib/openzfs/module/os/freebsd/spl/callb.c
new file mode 100644
index 000000000000..fffa85b6b91b
--- /dev/null
+++ b/sys/contrib/openzfs/module/os/freebsd/spl/callb.c
@@ -0,0 +1,373 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/sysmacros.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/mutex.h>
+#include <sys/condvar.h>
+#include <sys/callb.h>
+#include <sys/kmem.h>
+#include <sys/cmn_err.h>
+#include <sys/debug.h>
+#include <sys/kobj.h>
+#include <sys/systm.h>	/* for delay() */
+#include <sys/taskq.h>  /* For TASKQ_NAMELEN */
+#include <sys/kernel.h>
+
+#define	CB_MAXNAME	TASKQ_NAMELEN
+
+/*
+ * The callb mechanism provides generic event scheduling/echoing.
+ * A callb function is registered and called on behalf of the event.
+ */
+typedef struct callb {
+	struct callb	*c_next; 	/* next in class or on freelist */
+	kthread_id_t	c_thread;	/* ptr to caller's thread struct */
+	char		c_flag;		/* info about the callb state */
+	uchar_t		c_class;	/* this callb's class */
+	kcondvar_t	c_done_cv;	/* signal callb completion */
+	boolean_t	(*c_func)(void *, int);
+					/* cb function: returns true if ok */
+	void		*c_arg;		/* arg to c_func */
+	char		c_name[CB_MAXNAME+1]; /* debug:max func name length */
+} callb_t;
+
+/*
+ * callb c_flag bitmap definitions
+ */
+#define	CALLB_FREE		0x0
+#define	CALLB_TAKEN		0x1
+#define	CALLB_EXECUTING		0x2
+
+/*
+ * Basic structure for a callb table.
+ * All callbs are organized into different class groups described
+ * by ct_class array.
+ * The callbs within a class are single-linked and normally run by a
+ * serial execution.
+ */
+typedef struct callb_table {
+	kmutex_t ct_lock;		/* protect all callb states */
+	callb_t	*ct_freelist; 		/* free callb structures */
+	int	ct_busy;		/* != 0 prevents additions */
+	kcondvar_t ct_busy_cv;		/* to wait for not busy    */
+	int	ct_ncallb; 		/* num of callbs allocated */
+	callb_t	*ct_first_cb[NCBCLASS];	/* ptr to 1st callb in a class */
+} callb_table_t;
+
+int callb_timeout_sec = CPR_KTHREAD_TIMEOUT_SEC;
+
+static callb_id_t callb_add_common(boolean_t (*)(void *, int),
+    void *, int, char *, kthread_id_t);
+
+static callb_table_t callb_table;	/* system level callback table */
+static callb_table_t *ct = &callb_table;
+static kmutex_t	callb_safe_mutex;
+callb_cpr_t	callb_cprinfo_safe = {
+	&callb_safe_mutex, CALLB_CPR_ALWAYS_SAFE, 0, {0, 0} };
+
+/*
+ * Init all callb tables in the system.
+ */
+static void
+callb_init(void *dummy __unused)
+{
+	callb_table.ct_busy = 0;	/* mark table open for additions */
+	mutex_init(&callb_safe_mutex, NULL, MUTEX_DEFAULT, NULL);
+	mutex_init(&callb_table.ct_lock, NULL, MUTEX_DEFAULT, NULL);
+}
+
+static void
+callb_fini(void *dummy __unused)
+{
+	callb_t *cp;
+	int i;
+
+	mutex_enter(&ct->ct_lock);
+	for (i = 0; i < 16; i++) {
+		while ((cp = ct->ct_freelist) != NULL) {
+			ct->ct_freelist = cp->c_next;
+			ct->ct_ncallb--;
+			kmem_free(cp, sizeof (callb_t));
+		}
+		if (ct->ct_ncallb == 0)
+			break;
+		/* Not all callbacks finished, waiting for the rest. */
+		mutex_exit(&ct->ct_lock);
+		tsleep(ct, 0, "callb", hz / 4);
+		mutex_enter(&ct->ct_lock);
+	}
+	if (ct->ct_ncallb > 0)
+		printf("%s: Leaked %d callbacks!\n", __func__, ct->ct_ncallb);
+	mutex_exit(&ct->ct_lock);
+	mutex_destroy(&callb_safe_mutex);
+	mutex_destroy(&callb_table.ct_lock);
+}
+
+/*
+ * callout_add() is called to register func() be called later.
+ */
+static callb_id_t
+callb_add_common(boolean_t (*func)(void *arg, int code),
+    void *arg, int class, char *name, kthread_id_t t)
+{
+	callb_t *cp;
+
+	ASSERT(class < NCBCLASS);
+
+	mutex_enter(&ct->ct_lock);
+	while (ct->ct_busy)
+		cv_wait(&ct->ct_busy_cv, &ct->ct_lock);
+	if ((cp = ct->ct_freelist) == NULL) {
+		ct->ct_ncallb++;
+		cp = (callb_t *)kmem_zalloc(sizeof (callb_t), KM_SLEEP);
+	}
+	ct->ct_freelist = cp->c_next;
+	cp->c_thread = t;
+	cp->c_func = func;
+	cp->c_arg = arg;
+	cp->c_class = (uchar_t)class;
+	cp->c_flag |= CALLB_TAKEN;
+#ifdef ZFS_DEBUG
+	if (strlen(name) > CB_MAXNAME)
+		cmn_err(CE_WARN, "callb_add: name of callback function '%s' "
+		    "too long -- truncated to %d chars",
+		    name, CB_MAXNAME);
+#endif
+	(void) strncpy(cp->c_name, name, CB_MAXNAME);
+	cp->c_name[CB_MAXNAME] = '\0';
+
+	/*
+	 * Insert the new callb at the head of its class list.
+	 */
+	cp->c_next = ct->ct_first_cb[class];
+	ct->ct_first_cb[class] = cp;
+
+	mutex_exit(&ct->ct_lock);
+	return ((callb_id_t)cp);
+}
+
+/*
+ * The default function to add an entry to the callback table.  Since
+ * it uses curthread as the thread identifier to store in the table,
+ * it should be used for the normal case of a thread which is calling
+ * to add ITSELF to the table.
+ */
+callb_id_t
+callb_add(boolean_t (*func)(void *arg, int code),
+    void *arg, int class, char *name)
+{
+	return (callb_add_common(func, arg, class, name, curthread));
+}
+
+/*
+ * A special version of callb_add() above for use by threads which
+ * might be adding an entry to the table on behalf of some other
+ * thread (for example, one which is constructed but not yet running).
+ * In this version the thread id is an argument.
+ */
+callb_id_t
+callb_add_thread(boolean_t (*func)(void *arg, int code),
+    void *arg, int class, char *name, kthread_id_t t)
+{
+	return (callb_add_common(func, arg, class, name, t));
+}
+
+/*
+ * callout_delete() is called to remove an entry identified by id
+ * that was originally placed there by a call to callout_add().
+ * return -1 if fail to delete a callb entry otherwise return 0.
+ */
+int
+callb_delete(callb_id_t id)
+{
+	callb_t **pp;
+	callb_t *me = (callb_t *)id;
+
+	mutex_enter(&ct->ct_lock);
+
+	for (;;) {
+		pp = &ct->ct_first_cb[me->c_class];
+		while (*pp != NULL && *pp != me)
+			pp = &(*pp)->c_next;
+
+#ifdef ZFS_DEBUG
+		if (*pp != me) {
+			cmn_err(CE_WARN, "callb delete bogus entry 0x%p",
+			    (void *)me);
+			mutex_exit(&ct->ct_lock);
+			return (-1);
+		}
+#endif /* DEBUG */
+
+		/*
+		 * It is not allowed to delete a callb in the middle of
+		 * executing otherwise, the callb_execute() will be confused.
+		 */
+		if (!(me->c_flag & CALLB_EXECUTING))
+			break;
+
+		cv_wait(&me->c_done_cv, &ct->ct_lock);
+	}
+	/* relink the class list */
+	*pp = me->c_next;
+
+	/* clean up myself and return the free callb to the head of freelist */
+	me->c_flag = CALLB_FREE;
+	me->c_next = ct->ct_freelist;
+	ct->ct_freelist = me;
+
+	mutex_exit(&ct->ct_lock);
+	return (0);
+}
+
+/*
+ * class:	indicates to execute all callbs in the same class;
+ * code:	optional argument for the callb functions.
+ * return:	 = 0: success
+ *		!= 0: ptr to string supplied when callback was registered
+ */
+void *
+callb_execute_class(int class, int code)
+{
+	callb_t *cp;
+	void *ret = NULL;
+
+	ASSERT(class < NCBCLASS);
+
+	mutex_enter(&ct->ct_lock);
+
+	for (cp = ct->ct_first_cb[class];
+	    cp != NULL && ret == 0; cp = cp->c_next) {
+		while (cp->c_flag & CALLB_EXECUTING)
+			cv_wait(&cp->c_done_cv, &ct->ct_lock);
+		/*
+		 * cont if the callb is deleted while we're sleeping
+		 */
+		if (cp->c_flag == CALLB_FREE)
+			continue;
+		cp->c_flag |= CALLB_EXECUTING;
+
+#ifdef CALLB_DEBUG
+		printf("callb_execute: name=%s func=%p arg=%p\n",
+		    cp->c_name, (void *)cp->c_func, (void *)cp->c_arg);
+#endif /* CALLB_DEBUG */
+
+		mutex_exit(&ct->ct_lock);
+		/* If callback function fails, pass back client's name */
+		if (!(*cp->c_func)(cp->c_arg, code))
+			ret = cp->c_name;
+		mutex_enter(&ct->ct_lock);
+
+		cp->c_flag &= ~CALLB_EXECUTING;
+		cv_broadcast(&cp->c_done_cv);
+	}
+	mutex_exit(&ct->ct_lock);
+	return (ret);
+}
+
+/*
+ * callers make sure no recursive entries to this func.
+ * dp->cc_lockp is registered by callb_add to protect callb_cpr_t structure.
+ *
+ * When calling to stop a kernel thread (code == CB_CODE_CPR_CHKPT) we
+ * use a cv_timedwait() in case the kernel thread is blocked.
+ *
+ * Note that this is a generic callback handler for daemon CPR and
+ * should NOT be changed to accommodate any specific requirement in a daemon.
+ * Individual daemons that require changes to the handler shall write
+ * callback routines in their own daemon modules.
+ */
+boolean_t
+callb_generic_cpr(void *arg, int code)
+{
+	callb_cpr_t *cp = (callb_cpr_t *)arg;
+	clock_t ret = 0;			/* assume success */
+
+	mutex_enter(cp->cc_lockp);
+
+	switch (code) {
+	case CB_CODE_CPR_CHKPT:
+		cp->cc_events |= CALLB_CPR_START;
+#ifdef CPR_NOT_THREAD_SAFE
+		while (!(cp->cc_events & CALLB_CPR_SAFE))
+			/* cv_timedwait() returns -1 if it times out. */
+			if ((ret = cv_reltimedwait(&cp->cc_callb_cv,
+			    cp->cc_lockp, (callb_timeout_sec * hz),
+			    TR_CLOCK_TICK)) == -1)
+				break;
+#endif
+		break;
+
+	case CB_CODE_CPR_RESUME:
+		cp->cc_events &= ~CALLB_CPR_START;
+		cv_signal(&cp->cc_stop_cv);
+		break;
+	}
+	mutex_exit(cp->cc_lockp);
+	return (ret != -1);
+}
+
+/*
+ * The generic callback function associated with kernel threads which
+ * are always considered safe.
+ */
+/* ARGSUSED */
+boolean_t
+callb_generic_cpr_safe(void *arg, int code)
+{
+	return (B_TRUE);
+}
+/*
+ * Prevent additions to callback table.
+ */
+void
+callb_lock_table(void)
+{
+	mutex_enter(&ct->ct_lock);
+	ASSERT(ct->ct_busy == 0);
+	ct->ct_busy = 1;
+	mutex_exit(&ct->ct_lock);
+}
+
+/*
+ * Allow additions to callback table.
+ */
+void
+callb_unlock_table(void)
+{
+	mutex_enter(&ct->ct_lock);
+	ASSERT(ct->ct_busy != 0);
+	ct->ct_busy = 0;
+	cv_broadcast(&ct->ct_busy_cv);
+	mutex_exit(&ct->ct_lock);
+}
+
+SYSINIT(sol_callb, SI_SUB_DRIVERS, SI_ORDER_FIRST, callb_init, NULL);
+SYSUNINIT(sol_callb, SI_SUB_DRIVERS, SI_ORDER_FIRST, callb_fini, NULL);