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vm: force meminfo-writer to wait for the first user process (#392)

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meminfo-writer will wait for SIGUSR1 - send by qrexec-agent on the first
qvm-run from dom0.
This commit is contained in:
Marek Marczykowski 2011-12-26 23:29:07 +01:00
parent 0cab96ad6d
commit b8b5cf0a17
4 changed files with 75 additions and 3 deletions
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2
appvm/qubes_core_appvm
View File

@ -64,7 +64,7 @@ start()
if [ "$start_meminfo_writer" != "0" ]; then
MEM_CHANGE_THRESHOLD_KB=30000
MEMINFO_DELAY_USEC=100000
/usr/lib/qubes/meminfo-writer $MEM_CHANGE_THRESHOLD_KB $MEMINFO_DELAY_USEC &
/usr/lib/qubes/meminfo-writer $MEM_CHANGE_THRESHOLD_KB $MEMINFO_DELAY_USEC /var/run/meminfo-writer.pid
fi
success

48
common/meminfo-writer.c
View File

@ -5,10 +5,12 @@
#include <xs.h>
#include <syslog.h>
#include <string.h>
#include <signal.h>
unsigned long prev_used_mem;
int used_mem_change_threshold;
int delay;
int usr1_received;
char *parse(char *buf)
{
@ -73,7 +75,10 @@ char *parse(char *buf)
void usage()
{
fprintf(stderr,
"usage: meminfo_writer threshold_in_kb delay_in_us\n");
"usage: meminfo_writer threshold_in_kb delay_in_us [pidfile]\n");
fprintf(stderr, " When pidfile set, meminfo-writer will:\n");
fprintf(stderr, " - fork into background\n");
fprintf(stderr, " - wait for SIGURS1 (in background) before starting main work\n");
exit(1);
}
@ -85,6 +90,10 @@ void send_to_qmemman(struct xs_handle *xs, char *data)
}
}
void usr1_handler(int sig) {
usr1_received = 1;
}
int main(int argc, char **argv)
{
char buf[4096];
@ -93,13 +102,48 @@ int main(int argc, char **argv)
int fd;
struct xs_handle *xs;
if (argc != 3)
if (argc != 3 && argc != 4)
usage();
used_mem_change_threshold = atoi(argv[1]);
delay = atoi(argv[2]);
if (!used_mem_change_threshold || !delay)
usage();
if (argc == 4) {
pid_t pid;
sigset_t mask, oldmask;
switch (pid = fork()) {
case -1:
perror("fork");
exit(1);
case 0:
sigemptyset (&mask);
sigaddset (&mask, SIGUSR1);
/* Wait for a signal to arrive. */
sigprocmask (SIG_BLOCK, &mask, &oldmask);
usr1_received = 0;
signal(SIGUSR1, usr1_handler);
while (!usr1_received)
sigsuspend (&oldmask);
sigprocmask (SIG_UNBLOCK, &mask, NULL);
break;
default:
fd = open(argv[3], O_CREAT | O_TRUNC | O_WRONLY, 0666);
if (fd < 0) {
perror("open pidfile");
exit(1);
}
n = sprintf(buf, "%d\n", pid);
if (write(fd, buf, n) != n) {
perror("write pid");
exit(1);
}
close(fd);
exit(0);
}
}
fd = open("/proc/meminfo", O_RDONLY);
if (fd < 0) {
perror("open meminfo");

1
qrexec/qrexec.h
View File

@ -27,6 +27,7 @@
#define QREXEC_AGENT_TRIGGER_PATH "/var/run/qubes/qrexec_agent"
#define QREXEC_AGENT_FDPASS_PATH "/var/run/qubes/qrexec_agent_fdpass"
#define MEMINFO_WRITER_PIDFILE "/var/run/meminfo-writer.pid"
enum {
MSG_CLIENT_TO_SERVER_EXEC_CMDLINE = 0x100,

27
qrexec/qrexec_agent.c
View File

@ -70,6 +70,8 @@ struct _client_info client_info[MAX_FDS];
int trigger_fd;
int passfd_socket;
int meminfo_write_started = 0;
void init()
{
peer_server_init(REXEC_PORT);
@ -81,6 +83,29 @@ void init()
open(QREXEC_AGENT_TRIGGER_PATH, O_RDONLY | O_NONBLOCK);
}
void wake_meminfo_writer() {
FILE *f;
pid_t pid;
if (meminfo_write_started)
/* wake meminfo-writer only once */
return;
f = fopen(MEMINFO_WRITER_PIDFILE, "r");
if (f == NULL) {
/* no meminfo-writer found, ignoring */
return;
}
if (fscanf(f, "%d", &pid) < 1) {
/* no meminfo-writer found, ignoring */
return;
}
fclose(f);
kill(pid, SIGUSR1);
meminfo_write_started = 1;
}
void no_colon_in_cmd()
{
fprintf(stderr,
@ -330,9 +355,11 @@ void handle_server_data()
handle_connect_existing(s_hdr.client_id, s_hdr.len);
break;
case MSG_SERVER_TO_AGENT_EXEC_CMDLINE:
wake_meminfo_writer();
handle_exec(s_hdr.client_id, s_hdr.len);
break;
case MSG_SERVER_TO_AGENT_JUST_EXEC:
wake_meminfo_writer();
handle_just_exec(s_hdr.client_id, s_hdr.len);
break;
case MSG_SERVER_TO_AGENT_INPUT: