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qemu-storage-daemon: add --pidfile option

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Daemons often have a --pidfile option where the pid is written to a file
so that scripts can stop the daemon by sending a signal.

The pid file also acts as a lock to prevent multiple instances of the
daemon from launching for a given pid file.

QEMU, qemu-nbd, qemu-ga, virtiofsd, and qemu-pr-helper all support the
--pidfile option. Add it to qemu-storage-daemon too.

Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210302142746.170535-1-stefanha@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi
2021-03-02 14:27:46 +00:00
committed by Kevin Wolf
parent 501a4b3681
commit 03d2b412aa
2 changed files with 50 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
storage-daemon/qemu-storage-daemon.c
+36
View File
@@ -59,6 +59,7 @@
#include "sysemu/runstate.h"
#include "trace/control.h"
static const char *pid_file;
static volatile bool exit_requested = false;
void qemu_system_killed(int signal, pid_t pid)
@@ -115,6 +116,8 @@ static void help(void)
" See the qemu(1) man page for documentation of the\n"
" objects that can be added.\n"
"\n"
" --pidfile <path> write process ID to a file after startup\n"
"\n"
QEMU_HELP_BOTTOM "\n",
error_get_progname());
}
@@ -126,6 +129,7 @@ enum {
OPTION_MONITOR,
OPTION_NBD_SERVER,
OPTION_OBJECT,
OPTION_PIDFILE,
};
extern QemuOptsList qemu_chardev_opts;
@@ -178,6 +182,7 @@ static void process_options(int argc, char *argv[])
{"monitor", required_argument, NULL, OPTION_MONITOR},
{"nbd-server", required_argument, NULL, OPTION_NBD_SERVER},
{"object", required_argument, NULL, OPTION_OBJECT},
{"pidfile", required_argument, NULL, OPTION_PIDFILE},
{"trace", required_argument, NULL, 'T'},
{"version", no_argument, NULL, 'V'},
{0, 0, 0, 0}
@@ -289,6 +294,9 @@ static void process_options(int argc, char *argv[])
qobject_unref(args);
break;
}
case OPTION_PIDFILE:
pid_file = optarg;
break;
case 1:
error_report("Unexpected argument");
exit(EXIT_FAILURE);
@@ -299,6 +307,27 @@ static void process_options(int argc, char *argv[])
loc_set_none();
}
static void pid_file_cleanup(void)
{
unlink(pid_file);
}
static void pid_file_init(void)
{
Error *err = NULL;
if (!pid_file) {
return;
}
if (!qemu_write_pidfile(pid_file, &err)) {
error_reportf_err(err, "cannot create PID file: ");
exit(EXIT_FAILURE);
}
atexit(pid_file_cleanup);
}
int main(int argc, char *argv[])
{
#ifdef CONFIG_POSIX
@@ -326,6 +355,13 @@ int main(int argc, char *argv[])
qemu_init_main_loop(&error_fatal);
process_options(argc, argv);
/*
* Write the pid file after creating chardevs, exports, and NBD servers but
* before accepting connections. This ordering is documented. Do not change
* it.
*/
pid_file_init();
while (!exit_requested) {
main_loop_wait(false);
}