Remove mgr_pipe for communicating from manage to monitor.

Data is being passed in shared memory, so the pipe is only being
use as a wakeup.  This can more easily be done with a thread-signal.

managemon.c

@@ -85,6 +85,7 @@
 #endif
 #include	"mdadm.h"
 #include	"mdmon.h"
+#include	<sys/syscall.h>
 #include	<sys/socket.h>
 #include	<signal.h>
 
@@ -143,15 +144,11 @@ static struct active_array *duplicate_aa(struct active_array *aa)
 	return newa;
 }
 
-static void write_wakeup(struct supertype *c)
+static void wakeup_monitor(void)
 {
-	static struct md_generic_cmd cmd = { .action = md_action_ping_monitor };
-	int err;
-
-	active_cmd = &cmd;
-
-	/* send the monitor thread a pointer to the ping action */
-	write(c->mgr_pipe[1], &err, 1);
+	/* tgkill(getpid(), mon_tid, SIGUSR1); */
+	int pid = getpid();
+	syscall(SYS_tgkill, pid, mon_tid, SIGUSR1);
 }
 
 static void remove_old(void)
@@ -177,7 +174,7 @@ static void replace_array(struct supertype *container,
 	 */
 	remove_old();
 	while (pending_discard) {
-		write_wakeup(container);
+		wakeup_monitor();
 		while (discard_this == NULL)
 			sleep(1);
 		remove_old();
@@ -186,7 +183,7 @@ static void replace_array(struct supertype *container,
 	new->replaces = old;
 	new->next = container->arrays;
 	container->arrays = new;
-	write_wakeup(container);
+	wakeup_monitor();
 }
 
 struct metadata_update *update_queue = NULL;
@@ -207,7 +204,7 @@ void check_update_queue(struct supertype *container)
 	    update_queue_pending) {
 		update_queue = update_queue_pending;
 		update_queue_pending = NULL;
-		write_wakeup(container);
+		wakeup_monitor();
 	}
 }
 
@@ -433,16 +430,7 @@ void manage(struct mdstat_ent *mdstat, struct supertype *container)
 
 static int handle_message(struct supertype *container, struct md_message *msg)
 {
-	struct md_generic_cmd *cmd = msg->buf;
-
-	if (!cmd)
-		return 0;
-
-	switch (cmd->action) {
-
-	default:
-		return -1;
-	}
+	return -1;
 }
 
 void read_sock(struct supertype *container)
@@ -485,26 +473,17 @@ void read_sock(struct supertype *container)
 	close(fd);
 }
 
-static int woke = 0;
-void wake_me(int sig)
-{
-	woke = 1;
-}
-
 int exit_now = 0;
 int manager_ready = 0;
 void do_manager(struct supertype *container)
 {
 	struct mdstat_ent *mdstat;
-	sigset_t block, orig;
+	sigset_t set;
 
-	sigemptyset(&block);
-	sigaddset(&block, SIGUSR1);
-
-	signal(SIGUSR1, wake_me);
+	sigprocmask(SIG_UNBLOCK, NULL, &set);
+	sigdelset(&set, SIGUSR1);
 
 	do {
-		woke = 0;
 
 		if (exit_now)
 			exit(0);
@@ -522,9 +501,7 @@ void do_manager(struct supertype *container)
 		check_update_queue(container);
 
 		manager_ready = 1;
-		sigprocmask(SIG_SETMASK, &block, &orig);
-		if (woke == 0)
-			mdstat_wait_fd(container->sock, &orig);
-		sigprocmask(SIG_SETMASK, &orig, NULL);
+
+		mdstat_wait_fd(container->sock, &set);
 	} while(1);
 }

mdadm.h

@@ -582,7 +582,6 @@ struct supertype {
 	/* extra stuff used by mdmon */
 	struct active_array *arrays;
 	int sock; /* listen to external programs */
-	int mgr_pipe[2]; /* communicate between threads */
 	int devnum;
 	char *devname; /* e.g. md0.  This appears in metadata_verison:
 			*  external:/md0/12

mdmon.c

@@ -26,10 +26,12 @@
 
 #include	<unistd.h>
 #include	<stdlib.h>
+#include	<sys/types.h>
 #include	<sys/stat.h>
 #include	<sys/socket.h>
 #include	<sys/un.h>
 #include	<sys/mman.h>
+#include	<sys/syscall.h>
 #include	<stdio.h>
 #include	<errno.h>
 #include	<string.h>
@@ -43,17 +45,14 @@
 
 struct active_array *discard_this;
 struct active_array *pending_discard;
-struct md_generic_cmd *active_cmd;
+
+int mon_tid, mgr_tid;
 
 int run_child(void *v)
 {
 	struct supertype *c = v;
-	sigset_t set;
-	/* SIGUSR is sent from child to parent,  So child must block it */
-	sigemptyset(&set);
-	sigaddset(&set, SIGUSR1);
-	sigprocmask(SIG_BLOCK, &set, NULL);
 
+	mon_tid = syscall(SYS_gettid);
 	do_monitor(c);
 	return 0;
 }
@@ -63,22 +62,13 @@ int clone_monitor(struct supertype *container)
 	static char stack[4096];
 	int rv;
 
-	rv = pipe(container->mgr_pipe);
-	if (rv < 0)
-		return rv;
 
 	rv = clone(run_child, stack+4096-64,
 		   CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD,
 		   container);
-	if (rv < 0)
-		goto err_clone;
-	else
-		return rv;
-
- err_clone:
-	close(container->mgr_pipe[0]);
-	close(container->mgr_pipe[1]);
 
+	mgr_tid = syscall(SYS_gettid);
+	
 	return rv;
 }
 
@@ -176,11 +166,18 @@ static int make_control_sock(char *devname)
 	return sfd;
 }
 
+static void wake_me(int sig)
+{
+
+}
+
 int main(int argc, char *argv[])
 {
 	int mdfd;
 	struct mdinfo *mdi, *di;
 	struct supertype *container;
+	sigset_t set;
+
 	if (argc != 2) {
 		fprintf(stderr, "Usage: md-manage /device/name/for/container\n");
 		exit(2);
@@ -277,6 +274,14 @@ int main(int argc, char *argv[])
 
 	mlockall(MCL_FUTURE);
 
+	/* SIGUSR is sent between parent and child.  So both block it
+	 * and enable it only with pselect.
+	 */
+	sigemptyset(&set);
+	sigaddset(&set, SIGUSR1);
+	sigprocmask(SIG_BLOCK, &set, NULL);
+	signal(SIGUSR1, wake_me);
+
 	if (clone_monitor(container) < 0) {
 		fprintf(stderr, "md-manage: failed to start monitor process: %s\n",
 			strerror(errno));

mdmon.h

@@ -66,3 +66,4 @@ int read_dev_state(int fd);
 struct mdstat_ent *mdstat_read(int hold, int start);
 
 extern int exit_now, manager_ready;
+extern int mon_tid, mgr_tid;

monitor.c

@@ -1,7 +1,7 @@
 
 #include "mdadm.h"
 #include "mdmon.h"
-
+#include <sys/syscall.h>
 #include <sys/select.h>
 #include <signal.h>
 
@@ -138,7 +138,9 @@ int read_dev_state(int fd)
 
 static void signal_manager(void)
 {
-	kill(getpid(), SIGUSR1);
+	/* tgkill(getpid(), mon_tid, SIGUSR1); */
+	int pid = getpid();
+	syscall(SYS_tgkill, pid, mgr_tid, SIGUSR1);
 }
 
 /* Monitor a set of active md arrays - all of which share the
@@ -367,16 +369,6 @@ static void reconcile_failed(struct active_array *aa, struct mdinfo *failed)
 	}
 }
 
-static int handle_pipe(struct md_generic_cmd *cmd, struct active_array *aa)
-{
-	switch (cmd->action) {
-	case md_action_ping_monitor:
-		return 0;
-	}
-
-	return -1;
-}
-
 #ifdef DEBUG
 static void dprint_wake_reasons(fd_set *fds)
 {
@@ -407,8 +399,7 @@ static void dprint_wake_reasons(fd_set *fds)
 }
 #endif
 
-static int wait_and_act(struct supertype *container, int pfd,
-			int nowait)
+static int wait_and_act(struct supertype *container, int nowait)
 {
 	fd_set rfds;
 	int maxfd = 0;
@@ -419,7 +410,6 @@ static int wait_and_act(struct supertype *container, int pfd,
 
 	FD_ZERO(&rfds);
 
-	add_fd(&rfds, &maxfd, pfd);
 	for (ap = aap ; *ap ;) {
 		a = *ap;
 		/* once an array has been deactivated we want to
@@ -463,21 +453,15 @@ static int wait_and_act(struct supertype *container, int pfd,
 	}
 
 	if (!nowait) {
-		rv = select(maxfd+1, &rfds, NULL, NULL, NULL);
+		sigset_t set;
+		sigprocmask(SIG_UNBLOCK, NULL, &set);
+		sigdelset(&set, SIGUSR1);
+		rv = pselect(maxfd+1, &rfds, NULL, NULL, NULL, &set);
 
 		#ifdef DEBUG
 		dprint_wake_reasons(&rfds);
 		#endif
 
-		if (rv <= 0)
-			return rv;
-
-		if (FD_ISSET(pfd, &rfds)) {
-			int err = -1;
-
-			if (read(pfd, &err, 1) > 0)
-				err = handle_pipe(active_cmd, *aap);
-		}
 	}
 
 	if (update_queue) {
@@ -526,8 +510,7 @@ void do_monitor(struct supertype *container)
 	int rv;
 	int first = 1;
 	do {
-		rv = wait_and_act(container, container->mgr_pipe[0],
-				  first);
+		rv = wait_and_act(container, first);
 		first = 0;
 	} while (rv >= 0);
 }

msg.c

@@ -88,7 +88,7 @@ tx_rx_message(int fd, struct md_message *msg, int recv_send, int tmo)
 				break;
 			case TX_RX_NUM_BYTES:
 				if (msg->num_bytes >
-				    sizeof(union md_message_commands))
+				    1024*1024)
 					state = TX_RX_ERR;
 				else if (recv_send && msg->num_bytes) {
 					msg->buf = malloc(msg->num_bytes);

msg.h

@@ -27,21 +27,6 @@ struct md_message {
 	void *buf;
 };
 
-enum md_message_action {
-	md_action_ping_monitor,
-};
-
-struct md_generic_cmd {
-	enum md_message_action action;
-};
-
-/* union of all known command types, used to sanity check ->num_bytes
- * on the receive path
- */
-union md_message_commands {
-	struct md_generic_cmd generic;
-};
-
 extern const int start_magic;
 extern const int end_magic;