1 files changed, 213 insertions, 24 deletions

diff --git a/usr/src/lib/libidmap/common/utils.c b/usr/src/lib/libidmap/common/utils.c
index 1c073b75d6..1068e0aa2c 100644
--- a/usr/src/lib/libidmap/common/utils.c
+++ b/usr/src/lib/libidmap/common/utils.c
@@ -19,12 +19,9 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
-#pragma ident	"%Z%%M%	%I%	%E% SMI"
-
 /*
  * Utility routines
  */
@@ -33,6 +30,9 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <libintl.h>
+#include <assert.h>
+#include <ucontext.h>
+#include <pthread.h>
 #include "idmap_impl.h"
 
 #define	_UDT_SIZE_INCR	1
@@ -41,6 +41,21 @@
 
 static struct timeval TIMEOUT = { 25, 0 };
 
+struct idmap_handle {
+	CLIENT		*client;
+	boolean_t	failed;
+	rwlock_t	lock;
+};
+
+static struct idmap_handle idmap_handle = {
+	NULL,		/* client */
+	B_TRUE,		/* failed */
+	DEFAULTRWLOCK,	/* lock */
+};
+
+static idmap_stat _idmap_clnt_connect(void);
+static void _idmap_clnt_disconnect(void);
+
 idmap_retcode
 _udt_extend_batch(idmap_udt_handle_t *udthandle)
 {
@@ -103,13 +118,10 @@ _iter_get_next_list(int type, idmap_iter_t *iter,
 		void *arg, uchar_t **list, size_t valsize,
 		xdrproc_t xdr_arg_proc, xdrproc_t xdr_res_proc)
 {
-
-	CLIENT		*clnt;
-	enum clnt_stat	clntstat;
+	idmap_stat rc;
 
 	iter->next = 0;
 	iter->retlist = NULL;
-	_IDMAP_GET_CLIENT_HANDLE(iter->ih, clnt);
 
 	/* init the result */
 	if (*list) {
@@ -122,20 +134,25 @@ _iter_get_next_list(int type, idmap_iter_t *iter,
 	}
 	(void) memset(*list, 0, valsize);
 
-	clntstat = clnt_call(clnt, type,
+	rc = _idmap_clnt_call(type,
 	    xdr_arg_proc, (caddr_t)arg,
 	    xdr_res_proc, (caddr_t)*list,
 	    TIMEOUT);
-	if (clntstat != RPC_SUCCESS) {
+	if (rc != IDMAP_SUCCESS) {
 		free(*list);
-		return (_idmap_rpc2stat(clnt));
+		return (rc);
 	}
 	iter->retlist = *list;
 	return (IDMAP_SUCCESS);
 }
 
+/*
+ * Convert the return values from an RPC request into an idmap return code.
+ * Set errno on error.
+ */
+static
 idmap_stat
-_idmap_rpc2stat(CLIENT *clnt)
+_idmap_rpc2stat(enum clnt_stat clntstat, CLIENT *clnt)
 {
 	/*
 	 * We only deal with door_call(3C) errors here. We look at
@@ -144,19 +161,191 @@ _idmap_rpc2stat(CLIENT *clnt)
 	 * and others.
 	 */
 	struct rpc_err r_err;
-	if (clnt) {
-		clnt_geterr(clnt, &r_err);
-		errno = r_err.re_errno;
-		switch (r_err.re_errno) {
-		case ENOMEM:
-			return (IDMAP_ERR_MEMORY);
-		case EBADF:
-			return (IDMAP_ERR_RPC_HANDLE);
-		default:
-			return (IDMAP_ERR_RPC);
+
+	if (clntstat == RPC_SUCCESS)
+		return (IDMAP_SUCCESS);
+
+	clnt_geterr(clnt, &r_err);
+	errno = r_err.re_errno;
+	switch (r_err.re_errno) {
+	case ENOMEM:
+		return (IDMAP_ERR_MEMORY);
+	case EBADF:
+		return (IDMAP_ERR_RPC_HANDLE);
+	default:
+		return (IDMAP_ERR_RPC);
+	}
+}
+
+/*
+ * Management of the connection to idmapd.
+ *
+ * The intent is that connections to idmapd are automatically maintained,
+ * reconnecting if necessary.  No attempt is made to retry connnection
+ * attempts; a failure to connect yields an immediate error return.
+ *
+ * State of the connection is maintained through the "client" and "failed"
+ * elements of the handle structure:
+ *
+ * client   failed
+ * NULL     true     Failed on a previous request and was not recovered.
+ * NULL     false    Should never happen.
+ * nonNULL  true     Structure exists, but an error has occurred.  Waiting
+ *                   for a chance to attempt to reconnect.
+ * nonNULL  false    Connection is good.
+ *
+ * Note that the initial state is NULL/true, so that the first request
+ * will establish the initial connection.
+ *
+ * Concurrency is managed through the rw lock "lock".  Only the writer is
+ * allowed to connect or disconnect, and thus only the writer can set
+ * "failed" to "false".  Readers are allowed to use the "client" pointer,
+ * and to set "failed" to "true", indicating that they have encountered a
+ * failure.  The "client" pointer is only valid while one holds a reader
+ * lock.  Once "failed" has been set to "true", all requests (including
+ * the retry of the failing request) will attempt to gain the writer lock.
+ * When they succeed, indicating that there are no requests in flight and
+ * thus no outstanding references to the CLIENT structure, they check
+ * again to see if the connection is still failed (since another thread
+ * might have fixed it), and then if it is still failed they disconnect
+ * and reconnect.
+ */
+
+/*
+ * Make an RPC call.  Automatically reconnect if the connection to idmapd
+ * fails.  Convert RPC results to idmap return codes.
+ */
+idmap_stat
+_idmap_clnt_call(
+    const rpcproc_t procnum,
+    const xdrproc_t inproc,
+    const caddr_t in,
+    const xdrproc_t outproc,
+    caddr_t out,
+    const struct timeval tout)
+{
+	enum clnt_stat	clntstat;
+	idmap_stat rc;
+
+	(void) rw_rdlock(&idmap_handle.lock);
+	for (;;) {
+		if (idmap_handle.failed) {
+			/* No connection.  Bid to see if we should fix it. */
+			(void) rw_unlock(&idmap_handle.lock);
+			/* Somebody else might fix it here. */
+			(void) rw_wrlock(&idmap_handle.lock);
+			/*
+			 * At this point, everybody else is asleep waiting
+			 * for us.  Check to see if somebody else has already
+			 * fixed the problem.
+			 */
+			if (idmap_handle.failed) {
+				/* It's our job to fix. */
+				_idmap_clnt_disconnect();
+				rc = _idmap_clnt_connect();
+				if (rc != IDMAP_SUCCESS) {
+					/* We couldn't fix it. */
+					assert(idmap_handle.failed);
+					assert(idmap_handle.client == NULL);
+					break;
+				}
+				/* We fixed it. */
+				idmap_handle.failed = B_FALSE;
+			}
+
+			/* It's fixed now. */
+			(void) rw_unlock(&idmap_handle.lock);
+			/*
+			 * Starting here, somebody might declare it failed
+			 * again.
+			 */
+			(void) rw_rdlock(&idmap_handle.lock);
+			continue;
+		}
+
+		clntstat = clnt_call(idmap_handle.client, procnum, inproc, in,
+		    outproc, out, tout);
+		rc = _idmap_rpc2stat(clntstat, idmap_handle.client);
+		if (rc == IDMAP_ERR_RPC_HANDLE) {
+			/* Failed.  Needs to be reconnected. */
+			idmap_handle.failed = B_TRUE;
+			continue;
+		}
+
+		/* Success or unrecoverable failure. */
+		break;
+	}
+	(void) rw_unlock(&idmap_handle.lock);
+	return (rc);
+}
+
+#define	MIN_STACK_NEEDS	65536
+
+/*
+ * Connect to idmapd.
+ * Must be single-threaded through rw_wrlock(&idmap_handle.lock).
+ */
+static
+idmap_stat
+_idmap_clnt_connect(void)
+{
+	uint_t			sendsz = 0;
+	stack_t			st;
+
+	/*
+	 * clnt_door_call() alloca()s sendsz bytes (twice too, once for
+	 * the call args buffer and once for the call result buffer), so
+	 * we want to pick a sendsz that will be large enough, but not
+	 * too large.
+	 */
+	if (stack_getbounds(&st) == 0) {
+		/*
+		 * Estimate how much stack space is left;
+		 * st.ss_sp is the top of stack.
+		 */
+		if ((char *)&sendsz < (char *)st.ss_sp)
+			/* stack grows up */
+			sendsz = ((char *)st.ss_sp - (char *)&sendsz);
+		else
+			/* stack grows down */
+			sendsz = ((char *)&sendsz - (char *)st.ss_sp);
+
+		if (sendsz <= MIN_STACK_NEEDS) {
+			sendsz = 0;	/* RPC call may fail */
+		} else {
+			/* Leave 64Kb (just a guess) for our needs */
+			sendsz -= MIN_STACK_NEEDS;
+
+			/* Divide the stack space left by two */
+			sendsz = RNDUP(sendsz / 2);
+
+			/* Limit sendsz to 256KB */
+			if (sendsz > IDMAP_MAX_DOOR_RPC)
+				sendsz = IDMAP_MAX_DOOR_RPC;
 		}
 	}
 
-	/* null handle */
-	return (IDMAP_ERR_RPC_HANDLE);
+	idmap_handle.client = clnt_door_create(IDMAP_PROG, IDMAP_V1, sendsz);
+	if (idmap_handle.client == NULL)
+		return (IDMAP_ERR_RPC);
+
+	return (IDMAP_SUCCESS);
+}
+
+/*
+ * Disconnect from idmapd, if we're connected.
+ */
+static
+void
+_idmap_clnt_disconnect(void)
+{
+	CLIENT *clnt;
+
+	clnt = idmap_handle.client;
+	if (clnt != NULL) {
+		if (clnt->cl_auth)
+			auth_destroy(clnt->cl_auth);
+		clnt_destroy(clnt);
+		idmap_handle.client = NULL;
+	}
 }