Re: Concurrency problem when triggering many mounts simultaneously

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>> Hello Ian,
>>
>> What about this patch, do you think it can be committed?
>
> Yep, I think this is the best thing to do. I can't find the original
> message which has the patch and this message has all sorts of wrap going
> on. Could you send the patch again please.

Here it goes.

Thanks,
Leonardo

Use numeric protocol ids instead of protoent structs

The function getprotobyname() is not reentrant, so we can't call
it simultaneously from multiple threads. Instead of switching to
the reentrant version which adds more complexity to the code,
lets use numeric protocol IDs instead of protoent structures.

Index: autofs/include/rpc_subs.h
===================================================================
--- autofs.orig/include/rpc_subs.h
+++ autofs/include/rpc_subs.h
@@ -54,7 +54,7 @@ struct conn_info {
 	unsigned short port;
 	unsigned long program;
 	unsigned long version;
-	struct protoent *proto;
+	int proto;
 	unsigned int send_sz;
 	unsigned int recv_sz;
 	struct timeval timeout;
@@ -66,7 +66,7 @@ int rpc_udp_getclient(struct conn_info *
 void rpc_destroy_udp_client(struct conn_info *);
 int rpc_tcp_getclient(struct conn_info *, unsigned int, unsigned int);
 void rpc_destroy_tcp_client(struct conn_info *);
-int rpc_portmap_getclient(struct conn_info *, const char *, struct
sockaddr *, size_t, const char *, unsigned int);
+int rpc_portmap_getclient(struct conn_info *, const char *, struct
sockaddr *, size_t, int, unsigned int);
 int rpc_portmap_getport(struct conn_info *, struct pmap *, unsigned short *);
 int rpc_ping_proto(struct conn_info *);
 int rpc_ping(const char *, long, long, unsigned int);
Index: autofs/modules/replicated.c
===================================================================
--- autofs.orig/modules/replicated.c
+++ autofs/modules/replicated.c
@@ -423,7 +423,7 @@ void free_host_list(struct host **list)

 static unsigned int get_nfs_info(unsigned logopt, struct host *host,
 			 struct conn_info *pm_info, struct conn_info *rpc_info,
-			 const char *proto, unsigned int version, int port)
+			 int proto, unsigned int version, int port)
 {
 	unsigned int random_selection = host->options & MOUNT_FLAG_RANDOM_SELECT;
 	unsigned int use_weight_only = host->options & MOUNT_FLAG_USE_WEIGHT_ONLY;
@@ -437,22 +437,18 @@ static unsigned int get_nfs_info(unsigne
 	int status, count = 0;

 	if (host->addr)
-		debug(logopt, "called with host %s(%s) proto %s version 0x%x",
+		debug(logopt, "called with host %s(%s) proto %d version 0x%x",
 		      host->name, get_addr_string(host->addr, buf, len),
 		      proto, version);
 	else
 		debug(logopt,
-		      "called for host %s proto %s version 0x%x",
+		      "called for host %s proto %d version 0x%x",
 		      host->name, proto, version);

-	rpc_info->proto = getprotobyname(proto);
-	if (!rpc_info->proto)
-		return 0;
-
+	rpc_info->proto = proto;
 	memset(&parms, 0, sizeof(struct pmap));
-
 	parms.pm_prog = NFS_PROGRAM;
-	parms.pm_prot = rpc_info->proto->p_proto;
+	parms.pm_prot = proto;

 	if (!(version & NFS4_REQUESTED))
 		goto v3_ver;
@@ -483,7 +479,7 @@ static unsigned int get_nfs_info(unsigne
 		}
 	}

-	if (rpc_info->proto->p_proto == IPPROTO_UDP)
+	if (rpc_info->proto == IPPROTO_UDP)
 		status = rpc_udp_getclient(rpc_info, NFS_PROGRAM, NFS4_VERSION);
 	else
 		status = rpc_tcp_getclient(rpc_info, NFS_PROGRAM, NFS4_VERSION);
@@ -544,7 +540,7 @@ v3_ver:
 			goto v2_ver;
 	}

-	if (rpc_info->proto->p_proto == IPPROTO_UDP)
+	if (rpc_info->proto == IPPROTO_UDP)
 		status = rpc_udp_getclient(rpc_info, NFS_PROGRAM, NFS3_VERSION);
 	else
 		status = rpc_tcp_getclient(rpc_info, NFS_PROGRAM, NFS3_VERSION);
@@ -591,7 +587,7 @@ v2_ver:
 			goto done_ver;
 	}

-	if (rpc_info->proto->p_proto == IPPROTO_UDP)
+	if (rpc_info->proto == IPPROTO_UDP)
 		status = rpc_udp_getclient(rpc_info, NFS_PROGRAM, NFS2_VERSION);
 	else
 		status = rpc_tcp_getclient(rpc_info, NFS_PROGRAM, NFS2_VERSION);
@@ -622,7 +618,7 @@ v2_ver:
 	}

 done_ver:
-	if (rpc_info->proto->p_proto == IPPROTO_UDP) {
+	if (rpc_info->proto == IPPROTO_UDP) {
 		rpc_destroy_udp_client(rpc_info);
 		rpc_destroy_udp_client(pm_info);
 	} else {
@@ -679,7 +675,7 @@ static int get_vers_and_cost(unsigned lo

 	if (version & TCP_REQUESTED) {
 		supported = get_nfs_info(logopt, host,
-				   &pm_info, &rpc_info, "tcp", vers, port);
+				   &pm_info, &rpc_info, IPPROTO_TCP, vers, port);
 		if (IS_ERR(supported)) {
 			if (ERR(supported) == EHOSTUNREACH ||
 			    ERR(supported) == ETIMEDOUT)
@@ -692,7 +688,7 @@ static int get_vers_and_cost(unsigned lo

 	if (version & UDP_REQUESTED) {
 		supported = get_nfs_info(logopt, host,
-				   &pm_info, &rpc_info, "udp", vers, port);
+				   &pm_info, &rpc_info, IPPROTO_UDP, vers, port);
 		if (IS_ERR(supported)) {
 			if (!ret && ERR(supported) == ETIMEDOUT)
 				return ret;
@@ -713,7 +709,7 @@ static int get_supported_ver_and_cost(un
 	socklen_t len = INET6_ADDRSTRLEN;
 	char buf[len + 1];
 	struct conn_info pm_info, rpc_info;
-	const char *proto;
+	int proto;
 	unsigned int vers;
 	struct timeval start, end;
 	struct timezone tz;
@@ -752,10 +748,10 @@ static int get_supported_ver_and_cost(un
 	 *  So, we do the conversion here.
 	 */
 	if (version & UDP_SELECTED_MASK) {
-		proto = "udp";
+		proto = IPPROTO_UDP;
 		version >>= 8;
 	} else
-		proto = "tcp";
+		proto = IPPROTO_TCP;

 	switch (version) {
 	case NFS2_SUPPORTED:
@@ -772,9 +768,7 @@ static int get_supported_ver_and_cost(un
 		return 0;
 	}

-	rpc_info.proto = getprotobyname(proto);
-	if (!rpc_info.proto)
-		return 0;
+	rpc_info.proto = proto;

 	if (port > 0)
 		rpc_info.port = port;
@@ -790,14 +784,14 @@ static int get_supported_ver_and_cost(un

 		memset(&parms, 0, sizeof(struct pmap));
 		parms.pm_prog = NFS_PROGRAM;
-		parms.pm_prot = rpc_info.proto->p_proto;
+		parms.pm_prot = rpc_info.proto;
 		parms.pm_vers = vers;
 		ret = rpc_portmap_getport(&pm_info, &parms, &rpc_info.port);
 		if (ret < 0)
 			goto done;
 	}

-	if (rpc_info.proto->p_proto == IPPROTO_UDP)
+	if (rpc_info.proto == IPPROTO_UDP)
 		status = rpc_udp_getclient(&rpc_info, NFS_PROGRAM, vers);
 	else
 		status = rpc_tcp_getclient(&rpc_info, NFS_PROGRAM, vers);
@@ -819,7 +813,7 @@ static int get_supported_ver_and_cost(un
 		}
 	}
 done:
-	if (rpc_info.proto->p_proto == IPPROTO_UDP) {
+	if (rpc_info.proto == IPPROTO_UDP) {
 		rpc_destroy_udp_client(&rpc_info);
 		rpc_destroy_udp_client(&pm_info);
 	} else {
Index: autofs/lib/rpc_subs.c
===================================================================
--- autofs.orig/lib/rpc_subs.c
+++ autofs/lib/rpc_subs.c
@@ -170,7 +170,7 @@ static int rpc_do_create_client(struct s

 	*client = NULL;

-	proto = info->proto->p_proto;
+	proto = info->proto;
 	if (proto == IPPROTO_UDP)
 		type = SOCK_DGRAM;
 	else
@@ -201,7 +201,7 @@ static int rpc_do_create_client(struct s
 	in4_raddr = (struct sockaddr_in *) addr;
 	in4_raddr->sin_port = htons(info->port);

-	switch (info->proto->p_proto) {
+	switch (info->proto) {
 	case IPPROTO_UDP:
 		clnt = clntudp_bufcreate(in4_raddr,
 					 info->program, info->version,
@@ -241,7 +241,7 @@ static int rpc_do_create_client(struct s

 	*client = NULL;

-	proto = info->proto->p_proto;
+	proto = info->proto;
 	if (proto == IPPROTO_UDP)
 		type = SOCK_DGRAM;
 	else
@@ -292,11 +292,11 @@ static int rpc_do_create_client(struct s
 	nb_addr.maxlen = nb_addr.len = slen;
 	nb_addr.buf = addr;

-	if (info->proto->p_proto == IPPROTO_UDP)
+	if (info->proto == IPPROTO_UDP)
 		clnt = clnt_dg_create(*fd, &nb_addr,
 				      info->program, info->version,
 				      info->send_sz, info->recv_sz);
-	else if (info->proto->p_proto == IPPROTO_TCP) {
+	else if (info->proto == IPPROTO_TCP) {
 		ret = connect_nb(*fd, addr, slen, &info->timeout);
 		if (ret < 0)
 			return ret;
@@ -355,7 +355,7 @@ static int create_client(struct conn_inf
 	memset(&hints, 0, sizeof(hints));
 	hints.ai_flags = AI_ADDRCONFIG;
 	hints.ai_family = AF_UNSPEC;
-	if (info->proto->p_proto == IPPROTO_UDP)
+	if (info->proto == IPPROTO_UDP)
 		hints.ai_socktype = SOCK_DGRAM;
 	else
 		hints.ai_socktype = SOCK_STREAM;
@@ -370,7 +370,7 @@ static int create_client(struct conn_inf

 	haddr = ai;
 	while (haddr) {
-		if (haddr->ai_protocol != info->proto->p_proto) {
+		if (haddr->ai_protocol != info->proto) {
 			haddr = haddr->ai_next;
 			continue;
 		}
@@ -417,16 +417,11 @@ out_close:
 int rpc_udp_getclient(struct conn_info *info,
 		      unsigned int program, unsigned int version)
 {
-	struct protoent *pe_proto;
 	CLIENT *client;
 	int ret;

 	if (!info->client) {
-		pe_proto = getprotobyname("udp");
-		if (!pe_proto)
-			return -ENOENT;
-
-		info->proto = pe_proto;
+		info->proto = IPPROTO_UDP;
 		info->timeout.tv_sec = RPC_TOUT_UDP;
 		info->timeout.tv_usec = 0;
 		info->send_sz = UDPMSGSIZE;
@@ -458,16 +453,11 @@ void rpc_destroy_udp_client(struct conn_
 int rpc_tcp_getclient(struct conn_info *info,
 		      unsigned int program, unsigned int version)
 {
-	struct protoent *pe_proto;
 	CLIENT *client;
 	int ret;

 	if (!info->client) {
-		pe_proto = getprotobyname("tcp");
-		if (!pe_proto)
-			return -ENOENT;
-
-		info->proto = pe_proto;
+		info->proto = IPPROTO_TCP;
 		info->timeout.tv_sec = RPC_TOUT_TCP;
 		info->timeout.tv_usec = 0;
 		info->send_sz = 0;
@@ -513,23 +503,18 @@ void rpc_destroy_tcp_client(struct conn_

 int rpc_portmap_getclient(struct conn_info *info,
 			  const char *host, struct sockaddr *addr, size_t addr_len,
-			  const char *proto, unsigned int option)
+			  int proto, unsigned int option)
 {
-	struct protoent *pe_proto;
 	CLIENT *client;
 	int ret;

-	pe_proto = getprotobyname(proto);
-	if (!pe_proto)
-		return -ENOENT;
-
 	info->host = host;
 	info->addr = addr;
 	info->addr_len = addr_len;
 	info->program = PMAPPROG;
 	info->port = PMAPPORT;
 	info->version = PMAPVERS;
-	info->proto = pe_proto;
+	info->proto = proto;
 	info->send_sz = RPCSMALLMSGSIZE;
 	info->recv_sz = RPCSMALLMSGSIZE;
 	info->timeout.tv_sec = PMAP_TOUT_UDP;
@@ -537,7 +522,7 @@ int rpc_portmap_getclient(struct conn_in
 	info->close_option = option;
 	info->client = NULL;

-	if (pe_proto->p_proto == IPPROTO_TCP)
+	if (info->proto == IPPROTO_TCP)
 		info->timeout.tv_sec = PMAP_TOUT_TCP;

 	ret = create_client(info, &client);
@@ -555,7 +540,7 @@ int rpc_portmap_getport(struct conn_info
 	struct conn_info pmap_info;
 	CLIENT *client;
 	enum clnt_stat status;
-	int proto = info->proto->p_proto;
+	int proto = info->proto;
 	int ret;

 	memset(&pmap_info, 0, sizeof(struct conn_info));
@@ -633,13 +618,13 @@ int rpc_ping_proto(struct conn_info *inf
 {
 	CLIENT *client;
 	enum clnt_stat status;
-	int proto = info->proto->p_proto;
+	int proto = info->proto;
 	int ret;

 	if (info->client)
 		client = info->client;
 	else {
-		if (info->proto->p_proto == IPPROTO_UDP) {
+		if (info->proto == IPPROTO_UDP) {
 			info->send_sz = UDPMSGSIZE;
 			info->recv_sz = UDPMSGSIZE;
 		}
@@ -688,7 +673,7 @@ int rpc_ping_proto(struct conn_info *inf

 static unsigned int __rpc_ping(const char *host,
 				unsigned long version,
-				char *proto,
+				int proto,
 				long seconds, long micros,
 				unsigned int option)
 {
@@ -696,6 +681,7 @@ static unsigned int __rpc_ping(const cha
 	struct conn_info info;
 	struct pmap parms;

+	info.proto = proto;
 	info.host = host;
 	info.addr = NULL;
 	info.addr_len = 0;
@@ -710,13 +696,9 @@ static unsigned int __rpc_ping(const cha

 	status = RPC_PING_FAIL;

-	info.proto = getprotobyname(proto);
-	if (!info.proto)
-		return status;
-
 	parms.pm_prog = NFS_PROGRAM;
 	parms.pm_vers = version;
-	parms.pm_prot = info.proto->p_proto;
+	parms.pm_prot = info.proto;
 	parms.pm_port = 0;

 	status = rpc_portmap_getport(&info, &parms, &info.port);
@@ -734,19 +716,19 @@ int rpc_ping(const char *host, long seco
 	unsigned long vers2 = NFS2_VERSION;
 	unsigned int status;

-	status = __rpc_ping(host, vers2, "udp", seconds, micros, option);
+	status = __rpc_ping(host, vers2, IPPROTO_UDP, seconds, micros, option);
 	if (status > 0)
 		return RPC_PING_V2 | RPC_PING_UDP;

-	status = __rpc_ping(host, vers3, "udp", seconds, micros, option);
+	status = __rpc_ping(host, vers3, IPPROTO_UDP, seconds, micros, option);
 	if (status > 0)
 		return RPC_PING_V3 | RPC_PING_UDP;

-	status = __rpc_ping(host, vers2, "tcp", seconds, micros, option);
+	status = __rpc_ping(host, vers2, IPPROTO_TCP, seconds, micros, option);
 	if (status > 0)
 		return RPC_PING_V2 | RPC_PING_TCP;

-	status = __rpc_ping(host, vers3, "tcp", seconds, micros, option);
+	status = __rpc_ping(host, vers3, IPPROTO_TCP, seconds, micros, option);
 	if (status > 0)
 		return RPC_PING_V3 | RPC_PING_TCP;

@@ -769,7 +751,7 @@ int rpc_time(const char *host,
 	double taken;
 	struct timeval start, end;
 	struct timezone tz;
-	char *proto = (ping_proto & RPC_PING_UDP) ? "udp" : "tcp";
+	int proto = (ping_proto & RPC_PING_UDP) ? IPPROTO_UDP : IPPROTO_TCP;
 	unsigned long vers = ping_vers;

 	gettimeofday(&start, &tz);
@@ -791,12 +773,12 @@ static int rpc_get_exports_proto(struct
 {
 	CLIENT *client;
 	enum clnt_stat status;
-	int proto = info->proto->p_proto;
+	int proto = info->proto;
 	unsigned int option = info->close_option;
 	int vers_entry;
 	int ret;

-	if (info->proto->p_proto == IPPROTO_UDP) {
+	if (info->proto == IPPROTO_UDP) {
 		info->send_sz = UDPMSGSIZE;
 		info->recv_sz = UDPMSGSIZE;
 	}
@@ -903,11 +885,9 @@ exports rpc_get_exports(const char *host
 	parms.pm_port = 0;

 	/* Try UDP first */
-	info.proto = getprotobyname("udp");
-	if (!info.proto)
-		goto try_tcp;
+	info.proto = IPPROTO_UDP;

-	parms.pm_prot = info.proto->p_proto;
+	parms.pm_prot = info.proto;

 	status = rpc_portmap_getport(&info, &parms, &info.port);
 	if (status < 0)
@@ -920,11 +900,9 @@ exports rpc_get_exports(const char *host
 		return exportlist;

 try_tcp:
-	info.proto = getprotobyname("tcp");
-	if (!info.proto)
-		return NULL;
+	info.proto = IPPROTO_TCP;

-	parms.pm_prot = info.proto->p_proto;
+	parms.pm_prot = info.proto;

 	status = rpc_portmap_getport(&info, &parms, &info.port);
 	if (status < 0)
--
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