Convert start_blktrace to run_program
Rework start_blktrace and use run_program to launch blktrace. Move the
argv-building into the function so that it's easier to work with and
clean it up a bit. Add a signal parameter to wait_program to optionally
kill the pid with a given signal before waiting for it.
Signed-off-by: Andrew Price <anprice@redhat.com>
diff --git a/tracers.c b/tracers.c
index 4844deb..6ecf24c 100644
--- a/tracers.c
+++ b/tracers.c
@@ -46,26 +46,12 @@
static pid_t blktrace_pid = 0;
static pid_t mpstat_pid = 0;
-char *blktrace_args[17 + MAX_DEVICES_PER_TRACE * 2] = {
- "blktrace",
- "-b", "8192",
- "-a", "queue",
- "-a", "complete",
- "-a", "issue",
- "-a", "notify",
- "-D", ".",
- NULL,
-};
-
char *mpstat_args[] = {
"mpstat",
"-P", "ALL", "1",
NULL,
};
-#define DEST_DIR_INDEX 12
-#define LAST_ARG 13
-
int stop_tracer(pid_t *tracer_pid)
{
int ret;
@@ -90,91 +76,82 @@
return 0;
}
-
-void stop_all_tracers(void)
+static void sig_handler_for_quit(int val)
{
- stop_tracer(&blktrace_pid);
+ fprintf(stderr, "Received signal %d. Terminating tracers.\n", val);
+ if (blktrace_pid) {
+ wait_program(blktrace_pid, "blktrace", SIGTERM);
+ blktrace_pid = 0;
+ }
stop_tracer(&mpstat_pid);
}
-void sig_handler_for_quit(int val)
-{
- fprintf(stderr, "iowatcher exiting with %d, stopping tracers\n", val);
- stop_all_tracers();
-}
-
-
int start_blktrace(char **devices, int num_devices, char *trace_name, char *dest)
{
- pid_t pid;
int ret;
- char **arg = blktrace_args;
int i;
- int arg_index;
+ char *argv[15 + MAX_DEVICES_PER_TRACE * 2];
+ int argc = 0;
- fprintf(stderr, "running blktrace");
if (!trace_name)
trace_name = "trace";
+ if (!dest)
+ dest = ".";
- arg_index = LAST_ARG;
- for (i = 0; i < num_devices; i++) {
- blktrace_args[arg_index++] = "-d";
- blktrace_args[arg_index++] = devices[i];
- }
+ argv[argc++] = "blktrace";
+ argv[argc++] = "-b";
+ argv[argc++] = "8192";
+ argv[argc++] = "-a";
+ argv[argc++] = "queue";
+ argv[argc++] = "-a";
+ argv[argc++] = "complete";
+ argv[argc++] = "-a";
+ argv[argc++] = "issue";
+ argv[argc++] = "-a";
+ argv[argc++] = "notify";
- /*
- * single device traces use -o and are put into
- * the dest dir if provided
- */
if (num_devices == 1) {
- blktrace_args[arg_index++] = "-o";
- blktrace_args[arg_index++] = trace_name;
- if (dest)
- blktrace_args[DEST_DIR_INDEX] = dest;
+ argv[argc++] = "-o";
+ argv[argc++] = trace_name;
} else {
- /*
- * multi device traces are put into a dest
- * dir based on the trace name
- */
- blktrace_args[DEST_DIR_INDEX] = trace_name;
+ /* Multiple devices output to a directory named trace_name */
+ dest = trace_name;
}
+ argv[argc++] = "-D";
+ argv[argc++] = dest;
- blktrace_args[arg_index] = NULL;
-
- while(*arg) {
- fprintf(stderr, " %s", *arg);
- arg++;
+ for (i = 0; i < num_devices; i++) {
+ argv[argc++] = "-d";
+ argv[argc++] = devices[i];
}
- fprintf(stderr, "\n");
-
-
- pid = fork();
- if (pid == 0) {
- ret = execvp("blktrace", blktrace_args);
- if (ret) {
- fprintf(stderr, "failed to exec blktrace error %s\n", strerror(errno));
- exit(errno);
- }
-
- } else {
- blktrace_pid = pid;
- signal(SIGTERM, sig_handler_for_quit);
- signal(SIGINT, sig_handler_for_quit);
- }
- return 0;
+ argv[argc] = NULL;
+ signal(SIGTERM, sig_handler_for_quit);
+ signal(SIGINT, sig_handler_for_quit);
+ ret = run_program(argc, argv, 0, &blktrace_pid);
+ return ret;
}
-int wait_program(pid_t pid, const char *pname)
+int wait_program(pid_t pid, const char *pname, int sig)
{
int status;
int ret = 0;
+ if (sig) {
+ ret = kill(pid, sig);
+ if (ret) {
+ fprintf(stderr, "Failed to send signal %d to %s (%lu): %s\n",
+ sig, pname, (long)pid, strerror(errno));
+ return ret;
+ }
+ fprintf(stderr, "Kill (%d): %s (%ld)\n", sig, pname, (long)pid);
+ }
+
waitpid(pid, &status, 0);
if (WIFEXITED(status)) {
ret = WEXITSTATUS(status);
if (ret == 127) /* spawnp failed after forking */
fprintf(stderr, "Failed to run '%s'\n", pname);
- } else if (WIFSIGNALED(status)) {
+ } else if (WIFSIGNALED(status) && sig && WTERMSIG(status) != sig) {
fprintf(stderr, "'%s' killed by signal %d\n", pname, WTERMSIG(status));
ret = -1;
}
@@ -196,7 +173,7 @@
if (err != 0) {
fprintf(stderr, "Could not run '%s': %s\n", argv[0], strerror(err));
} else if (wait) {
- err = wait_program(_pid, argv[0]);
+ err = wait_program(_pid, argv[0], 0);
} else if (!pid) {
fprintf(stderr, "Warning: %s (%ld): Not saving pid and not waiting for it.\n",
argv[0], (long)_pid);
@@ -208,13 +185,15 @@
int wait_for_tracers(void)
{
- int status = 0;
- stop_all_tracers();
if (blktrace_pid != 0) {
- waitpid(blktrace_pid, &status, WUNTRACED);
+ int err = wait_program(blktrace_pid, "blktrace", SIGINT);
+ if (err)
+ exit(1);
blktrace_pid = 0;
}
if (mpstat_pid != 0) {
+ int status = 0;
+ stop_tracer(&mpstat_pid);
waitpid(mpstat_pid, &status, WUNTRACED);
mpstat_pid = 0;
}
diff --git a/tracers.h b/tracers.h
index ed57f5d..77c31a6 100644
--- a/tracers.h
+++ b/tracers.h
@@ -18,7 +18,7 @@
#ifndef __IOWATCH_TRACERS
#define __IOWATCH_TRACERS
int run_program(int argc, char **argv, int wait, pid_t *pid);
-int wait_program(pid_t pid, const char *pname);
+int wait_program(pid_t pid, const char *pname, int signal);
int stop_blktrace(void);
int start_blktrace(char **devices, int num_devices, char *trace_name, char *dest);
int start_mpstat(char *trace_name);
