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[PATCH] convert udevsend/udevd to DGRAM and single-threaded

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On Fri, Feb 06, 2004 at 01:08:24AM -0500, Chris Friesen wrote:
>
> Kay, you said "unless we can get rid of _all_ the threads or at least
> getting faster, I don't want to change it."
>
> Well how about we get rid of all the threads, *and* we get faster?

Yes, we are twice as fast now on my box :)


> This patch applies to current bk trees, and does the following:
>
> 1) Switch to DGRAM sockets rather than STREAM.  This simplifies things
> as mentioned in the previous message.
>
> 2) Invalid sequence numbers are mapped to -1 rather than zero, since
> zero is a valid sequence number (I think).  Also, this allows for real
> speed tests using scripts starting at a zero sequence number, since that
> is what the initial expected sequence number is.
>
> 3) Get rid of all threading.  This is the biggie.  Some highlights:
> 	a) timeout using setitimer() and SIGALRM
> 	b) async child death notification via SIGCHLD
> 	c) these two signal handlers do nothing but raise volatile flags,
> 	all the
> work is done in the main loop
> 	d) locking no longer required


I cleaned up the rest of the comments, the whitespace and a few names to match
the whole thing. Please recheck it. Test script is switched to work on subsystem
'test' to let udev ignore it.
This commit is contained in:
kay.sievers@vrfy.org 2004-02-06 22:21:15 -08:00 committed by Greg KH
parent d2cf99df7d
commit 2f6cbd1911
4 changed files with 192 additions and 258 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Makefile
View File

@ -262,7 +262,7 @@ $(HELPER): $(HEADERS) udevinfo.o $(OBJS)
$(STRIPCMD) $@
$(DAEMON): udevd.h $(GEN_HEADERS) udevd.o
$(LD) $(LDFLAGS) -lpthread -o $@ $(CRT0) udevd.o $(LIB_OBJS) $(ARCH_LIB_OBJS)
$(LD) $(LDFLAGS) -o $@ $(CRT0) udevd.o $(LIB_OBJS) $(ARCH_LIB_OBJS)
$(STRIPCMD) $@
$(SENDER): udevd.h $(GEN_HEADERS) udevsend.o

65
test/udevd_test.sh
View File

@ -3,81 +3,86 @@
# add/rem/add/rem/add sequence of sda/sdb/sdc
# a few days longer and the socket of my usb-flash-reader is gone :)
export SEQNUM=0
export ACTION=add
export DEVPATH=/test/init
./udevsend test
export SEQNUM=3
export ACTION=add
export DEVPATH=/block/sdc
./udevsend block
export DEVPATH=/test/sdc
./udevsend test
export SEQNUM=1
export ACTION=add
export DEVPATH=/block/sda
./udevsend block
export DEVPATH=/test/sda
./udevsend test
export SEQNUM=2
export ACTION=add
export DEVPATH=/block/sdb
./udevsend block
export DEVPATH=/test/sdb
./udevsend test
export SEQNUM=4
export ACTION=remove
export DEVPATH=/block/sdc
./udevsend block
export DEVPATH=/test/sdc
./udevsend test
export SEQNUM=5
export ACTION=remove
export DEVPATH=/block/sdb
./udevsend block
export DEVPATH=/test/sdb
./udevsend test
export SEQNUM=8
export ACTION=add
export DEVPATH=/block/sdb
./udevsend block
export DEVPATH=/test/sdb
./udevsend test
export SEQNUM=6
export ACTION=remove
export DEVPATH=/block/sda
./udevsend block
export DEVPATH=/test/sda
./udevsend test
export SEQNUM=7
export ACTION=add
export DEVPATH=/block/sda
#./udevsend block
export DEVPATH=/test/sda
#./udevsend test
sleep 2
export SEQNUM=9
export ACTION=add
export DEVPATH=/block/sdc
./udevsend block
export DEVPATH=/test/sdc
./udevsend test
export SEQNUM=11
export ACTION=remove
export DEVPATH=/block/sdb
./udevsend block
export DEVPATH=/test/sdb
./udevsend test
export SEQNUM=10
export ACTION=remove
export DEVPATH=/block/sdc
./udevsend block
export DEVPATH=/test/sdc
./udevsend test
export SEQNUM=13
export ACTION=add
export DEVPATH=/block/sda
./udevsend block
export DEVPATH=/test/sda
./udevsend test
export SEQNUM=14
export ACTION=add
export DEVPATH=/block/sdb
./udevsend block
export DEVPATH=/test/sdb
./udevsend test
export SEQNUM=15
export ACTION=add
export DEVPATH=/block/sdc
./udevsend block
export DEVPATH=/test/sdc
./udevsend test
sleep 2
export SEQNUM=12
export ACTION=remove
export DEVPATH=/block/sda
./udevsend block
export DEVPATH=/test/sda
./udevsend test

301
udevd.c
View File

@ -2,6 +2,7 @@
* udevd.c - hotplug event serializer
*
* Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca>
*
*
* This program is free software; you can redistribute it and/or modify it
@ -19,7 +20,6 @@
*
*/
#include <pthread.h>
#include <stddef.h>
#include <sys/wait.h>
#include <signal.h>
@ -32,6 +32,7 @@
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>
#include "list.h"
#include "udev.h"
@ -39,22 +40,17 @@
#include "udevd.h"
#include "logging.h"
unsigned char logname[42];
static pthread_mutex_t msg_lock;
static pthread_mutex_t msg_active_lock;
static pthread_cond_t msg_active;
static pthread_mutex_t exec_lock;
static pthread_mutex_t exec_active_lock;
static pthread_cond_t exec_active;
static pthread_mutex_t running_lock;
static pthread_attr_t thr_attr;
static int expected_seqnum = 0;
volatile static int children_waiting;
volatile static int msg_q_timeout;
LIST_HEAD(msg_list);
LIST_HEAD(exec_list);
LIST_HEAD(running_list);
static void exec_queue_manager(void);
static void msg_queue_manager(void);
static void msg_dump_queue(void)
{
@ -75,17 +71,16 @@ static struct hotplug_msg *msg_create(void)
struct hotplug_msg *new_msg;
new_msg = malloc(sizeof(struct hotplug_msg));
if (new_msg == NULL) {
if (new_msg == NULL)
dbg("error malloc");
return NULL;
}
return new_msg;
}
static void msg_delete(struct hotplug_msg *msg)
static void run_queue_delete(struct hotplug_msg *msg)
{
if (msg != NULL)
free(msg);
list_del(&msg->list);
free(msg);
exec_queue_manager();
}
/* orders the message in the queue by sequence number */
@ -103,21 +98,16 @@ static void msg_queue_insert(struct hotplug_msg *msg)
/* store timestamp of queuing */
msg->queue_time = time(NULL);
/* signal queue activity to manager */
pthread_mutex_lock(&msg_active_lock);
pthread_cond_signal(&msg_active);
pthread_mutex_unlock(&msg_active_lock);
/* run msg queue manager */
msg_queue_manager();
return ;
}
/* forks event and removes event from run queue when finished */
static void *run_threads(void * parm)
static void udev_run(struct hotplug_msg *msg)
{
pid_t pid;
struct hotplug_msg *msg;
msg = parm;
setenv("ACTION", msg->action, 1);
setenv("DEVPATH", msg->devpath, 1);
@ -131,190 +121,124 @@ static void *run_threads(void * parm)
break;
case -1:
dbg("fork of child failed");
goto exit;
run_queue_delete(msg);
break;
default:
/* wait for exit of child */
dbg("==> exec seq %d [%d] working at '%s'",
msg->seqnum, pid, msg->devpath);
wait(NULL);
dbg("<== exec seq %d came back", msg->seqnum);
/* get SIGCHLD in main loop */
dbg("==> exec seq %d [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
msg->pid = pid;
}
exit:
/* remove event from run list */
pthread_mutex_lock(&running_lock);
list_del_init(&msg->list);
pthread_mutex_unlock(&running_lock);
msg_delete(msg);
/* signal queue activity to exec manager */
pthread_mutex_lock(&exec_active_lock);
pthread_cond_signal(&exec_active);
pthread_mutex_unlock(&exec_active_lock);
pthread_exit(0);
}
/* returns already running task with devpath */
static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
{
struct hotplug_msg *loop_msg;
struct hotplug_msg *tmp_msg;
list_for_each_entry_safe(loop_msg, tmp_msg, &running_list, list)
list_for_each_entry(loop_msg, &running_list, list)
if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
return loop_msg;
return NULL;
}
/* queue management executes the events and delays events for the same devpath */
static void *exec_queue_manager(void * parm)
/* exec queue management routine executes the events and delays events for the same devpath */
static void exec_queue_manager()
{
struct hotplug_msg *loop_msg;
struct hotplug_msg *tmp_msg;
struct hotplug_msg *msg;
pthread_t run_tid;
while (1) {
pthread_mutex_lock(&exec_lock);
list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
msg = running_with_devpath(loop_msg);
if (msg == NULL) {
/* move event to run list */
pthread_mutex_lock(&running_lock);
list_move_tail(&loop_msg->list, &running_list);
pthread_mutex_unlock(&running_lock);
pthread_create(&run_tid, &thr_attr, run_threads, (void *) loop_msg);
dbg("moved seq %d to running list", loop_msg->seqnum);
} else {
dbg("delay seq %d, cause seq %d already working on '%s'",
loop_msg->seqnum, msg->seqnum, msg->devpath);
}
list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
msg = running_with_devpath(loop_msg);
if (!msg) {
/* move event to run list */
list_move_tail(&loop_msg->list, &running_list);
udev_run(loop_msg);
dbg("moved seq %d to running list", loop_msg->seqnum);
} else {
dbg("delay seq %d, cause seq %d already working on '%s'",
loop_msg->seqnum, msg->seqnum, msg->devpath);
}
pthread_mutex_unlock(&exec_lock);
/* wait for activation, new events or childs coming back */
pthread_mutex_lock(&exec_active_lock);
pthread_cond_wait(&exec_active, &exec_active_lock);
pthread_mutex_unlock(&exec_active_lock);
}
}
static void exec_queue_activate(void)
static void msg_move_exec(struct hotplug_msg *msg)
{
pthread_mutex_lock(&exec_active_lock);
pthread_cond_signal(&exec_active);
pthread_mutex_unlock(&exec_active_lock);
list_move_tail(&msg->list, &exec_list);
exec_queue_manager();
expected_seqnum = msg->seqnum+1;
dbg("moved seq %d to exec, next expected is %d",
msg->seqnum, expected_seqnum);
}
/* move message from incoming to exec queue */
static void msg_move_exec(struct list_head *head)
{
list_move_tail(head, &exec_list);
exec_queue_activate();
}
/* queue management thread handles the timeouts and dispatches the events */
static void *msg_queue_manager(void * parm)
/* msg queue management routine handles the timeouts and dispatches the events */
static void msg_queue_manager()
{
struct hotplug_msg *loop_msg;
struct hotplug_msg *tmp_msg;
time_t msg_age = 0;
struct timespec tv;
while (1) {
dbg("msg queue manager, next expected is %d", expected_seqnum);
pthread_mutex_lock(&msg_lock);
pthread_mutex_lock(&exec_lock);
dbg("msg queue manager, next expected is %d", expected_seqnum);
recheck:
list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
/* move event with expected sequence to the exec list */
if (loop_msg->seqnum == expected_seqnum) {
msg_move_exec(&loop_msg->list);
expected_seqnum++;
dbg("moved seq %d to exec, next expected is %d",
loop_msg->seqnum, expected_seqnum);
continue;
}
/* move event with expired timeout to the exec list */
msg_age = time(NULL) - loop_msg->queue_time;
if (msg_age > EVENT_TIMEOUT_SEC-1) {
msg_move_exec(&loop_msg->list);
expected_seqnum = loop_msg->seqnum+1;
dbg("moved seq %d to exec, reset next expected to %d",
loop_msg->seqnum, expected_seqnum);
goto recheck;
} else {
break;
}
list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
/* move event with expected sequence to the exec list */
if (loop_msg->seqnum == expected_seqnum) {
msg_move_exec(loop_msg);
continue;
}
msg_dump_queue();
pthread_mutex_unlock(&exec_lock);
pthread_mutex_unlock(&msg_lock);
/* wait until queue gets active or next message timeout expires */
pthread_mutex_lock(&msg_active_lock);
if (list_empty(&msg_list) == 0) {
tv.tv_sec = time(NULL) + EVENT_TIMEOUT_SEC - msg_age;
tv.tv_nsec = 0;
dbg("next event expires in %li seconds",
EVENT_TIMEOUT_SEC - msg_age);
pthread_cond_timedwait(&msg_active, &msg_active_lock, &tv);
/* move event with expired timeout to the exec list */
msg_age = time(NULL) - loop_msg->queue_time;
if (msg_age > EVENT_TIMEOUT_SEC-1) {
msg_move_exec(loop_msg);
goto recheck;
} else {
pthread_cond_wait(&msg_active, &msg_active_lock);
break;
}
pthread_mutex_unlock(&msg_active_lock);
}
msg_dump_queue();
if (list_empty(&msg_list) == 0) {
/* set timeout for remaining queued events */
struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
dbg("next event expires in %li seconds",
EVENT_TIMEOUT_SEC - msg_age);
setitimer(ITIMER_REAL, &itv, 0);
}
}
/* every connect creates a thread which gets the msg, queues it and exits */
static void *client_threads(void * parm)
/* receive the msg, do some basic sanity checks, and queue it */
static void handle_msg(int sock)
{
int sock;
struct hotplug_msg *msg;
int retval;
sock = (int) parm;
msg = msg_create();
if (msg == NULL) {
dbg("unable to store message");
goto exit;
return;
}
retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
if (retval < 0) {
dbg("unable to receive message");
goto exit;
if (errno != EINTR)
dbg("unable to receive message");
return;
}
if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
dbg("message magic '%s' doesn't match, ignore it", msg->magic);
msg_delete(msg);
goto exit;
free(msg);
return;
}
/* if no seqnum is given, we move straight to exec queue */
if (msg->seqnum == 0) {
pthread_mutex_lock(&exec_lock);
if (msg->seqnum == -1) {
list_add(&msg->list, &exec_list);
exec_queue_activate();
pthread_mutex_unlock(&exec_lock);
exec_queue_manager();
} else {
pthread_mutex_lock(&msg_lock);
msg_queue_insert(msg);
pthread_mutex_unlock(&msg_lock);
}
exit:
close(sock);
pthread_exit(0);
}
static void sig_handler(int signum)
@ -324,28 +248,48 @@ static void sig_handler(int signum)
case SIGTERM:
exit(20 + signum);
break;
case SIGALRM:
msg_q_timeout = 1;
break;
case SIGCHLD:
children_waiting = 1;
break;
default:
dbg("unhandled signal");
}
}
static void udev_done(int pid)
{
/* find msg associated with pid and delete it */
struct hotplug_msg *msg;
list_for_each_entry(msg, &running_list, list) {
if (msg->pid == pid) {
dbg("<== exec seq %d came back", msg->seqnum);
run_queue_delete(msg);
return;
}
}
}
int main(int argc, char *argv[])
{
int ssock;
int csock;
struct sockaddr_un saddr;
struct sockaddr_un caddr;
socklen_t addrlen;
socklen_t clen;
pthread_t cli_tid;
pthread_t mgr_msg_tid;
pthread_t mgr_exec_tid;
int retval;
init_logging("udevd");
signal(SIGINT, sig_handler);
signal(SIGTERM, sig_handler);
signal(SIGALRM, sig_handler);
signal(SIGCHLD, sig_handler);
/* we want these two to interrupt system calls */
siginterrupt(SIGALRM, 1);
siginterrupt(SIGCHLD, 1);
memset(&saddr, 0x00, sizeof(saddr));
saddr.sun_family = AF_LOCAL;
@ -353,48 +297,37 @@ int main(int argc, char *argv[])
strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
ssock = socket(AF_LOCAL, SOCK_STREAM, 0);
ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
if (ssock == -1) {
dbg("error getting socket");
exit(1);
}
/* the bind takes care of ensuring only one copy running */
retval = bind(ssock, &saddr, addrlen);
if (retval < 0) {
dbg("bind failed\n");
goto exit;
}
retval = listen(ssock, SOMAXCONN);
if (retval < 0) {
dbg("listen failed\n");
goto exit;
}
pthread_mutex_init(&msg_lock, NULL);
pthread_mutex_init(&msg_active_lock, NULL);
pthread_mutex_init(&exec_lock, NULL);
pthread_mutex_init(&exec_active_lock, NULL);
pthread_mutex_init(&running_lock, NULL);
/* set default attributes for created threads */
pthread_attr_init(&thr_attr);
pthread_attr_setdetachstate(&thr_attr, PTHREAD_CREATE_DETACHED);
pthread_attr_setstacksize(&thr_attr, 16 * 1024);
/* init queue management */
pthread_create(&mgr_msg_tid, &thr_attr, msg_queue_manager, NULL);
pthread_create(&mgr_exec_tid, &thr_attr, exec_queue_manager, NULL);
clen = sizeof(caddr);
/* main loop */
while (1) {
csock = accept(ssock, &caddr, &clen);
if (csock < 0) {
dbg("client accept failed\n");
continue;
handle_msg(ssock);
while(msg_q_timeout) {
msg_q_timeout = 0;
msg_queue_manager();
}
while(children_waiting) {
children_waiting = 0;
/* reap all dead children */
while(1) {
int pid = waitpid(-1, 0, WNOHANG);
if ((pid == -1) || (pid == 0))
break;
udev_done(pid);
}
}
pthread_create(&cli_tid, &thr_attr, client_threads, (void *) csock);
}
exit:
close(ssock);

82
udevsend.c
View File

@ -33,6 +33,7 @@
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <linux/stddef.h>
#include "udev.h"
#include "udev_version.h"
@ -119,13 +120,14 @@ int main(int argc, char* argv[])
char *subsystem;
char *seqnum;
int seq;
int retval = -EINVAL;
int retval = 1;
int size;
int loop;
struct timespec tspec;
int sock;
struct sockaddr_un saddr;
socklen_t addrlen;
int started_daemon = 0;
#ifdef DEBUG
init_logging("udevsend");
@ -151,11 +153,11 @@ int main(int argc, char* argv[])
seqnum = get_seqnum();
if (seqnum == NULL)
seq = 0;
seq = -1;
else
seq = atoi(seqnum);
sock = socket(AF_LOCAL, SOCK_STREAM, 0);
sock = socket(AF_LOCAL, SOCK_DGRAM, 0);
if (sock == -1) {
dbg("error getting socket");
goto exit;
@ -167,48 +169,42 @@ int main(int argc, char* argv[])
strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;
/* try to connect, if it fails start daemon */
retval = connect(sock, (struct sockaddr *) &saddr, addrlen);
if (retval != -1) {
goto send;
} else {
dbg("connect failed, try starting daemon...");
retval = start_daemon();
if (retval == 0) {
dbg("daemon started");
} else {
dbg("error starting daemon");
goto exit;
}
}
/* try to connect while daemon to starts */
tspec.tv_sec = 0;
tspec.tv_nsec = 100000000; /* 100 millisec */
size = build_hotplugmsg(&message, action, devpath, subsystem, seq);
/* If we can't send, try to start daemon and resend message */
loop = UDEVSEND_CONNECT_RETRY;
while (loop--) {
retval = connect(sock, (struct sockaddr *) &saddr, sizeof(saddr));
if (retval != -1)
goto send;
else
dbg("retry to connect %d",
UDEVSEND_CONNECT_RETRY - loop);
nanosleep(&tspec, NULL);
retval = sendto(sock, &message, size, 0, (struct sockaddr*)&saddr, addrlen);
if (retval != -1) {
retval = 0;
goto close_and_exit;
}
if (errno != ECONNREFUSED) {
dbg("error sending message");
goto close_and_exit;
}
if (!started_daemon) {
dbg("connect failed, try starting daemon...");
retval = start_daemon();
if (retval) {
dbg("error starting daemon");
goto exit;
}
dbg("daemon started");
started_daemon = 1;
} else {
dbg("retry to connect %d", UDEVSEND_CONNECT_RETRY - loop);
tspec.tv_sec = 0;
tspec.tv_nsec = 100000000; /* 100 millisec */
nanosleep(&tspec, NULL);
}
}
dbg("error connecting to daemon, start daemon failed");
goto exit;
send:
size = build_hotplugmsg(&message, action, devpath, subsystem, seq);
retval = send(sock, &message, size, 0);
if (retval == -1) {
dbg("error sending message");
close (sock);
goto exit;
}
close (sock);
return 0;
close_and_exit:
close(sock);
exit:
return 1;
return retval;
}