2007-10-12 Martin Hunt <hunt@redhat.com>

	Changes to separate the symbols from the command channel.

	* cap.c (init_cap): Add CAP_DAC_OVERRIDE.
	* staprun.h: Change init_ctl_channel prototype.
	* ctl.c (init_ctl_channel): Modify to open either
	a command or symbol channel. Use ".cmd" and ".symbols"
	as the new names.
	* mainloop.c (init_stapio): Call init_ctl_channel(0);
	* staprun.c (cleanup): Call stop_symbol_thread().
	(main): Call start_symbol_thread().
	* staprun_funcs.c (handle_symbols): Make a thread.
	(start_symbol_thread): New.
	(stop_symbol_thread): New.

8 files changed, 81 insertions, 27 deletions

diff --git a/runtime/staprun/ChangeLog b/runtime/staprun/ChangeLog
index 2a9029d0..f03f3606 100644
--- a/runtime/staprun/ChangeLog
+++ b/runtime/staprun/ChangeLog
@@ -1,3 +1,18 @@
+2007-10-12  Martin Hunt  <hunt@redhat.com>
+	Changes to separate the symbols from the command channel.
+	
+	* cap.c (init_cap): Add CAP_DAC_OVERRIDE.
+	* staprun.h: Change init_ctl_channel prototype.
+	* ctl.c (init_ctl_channel): Modify to open either
+	a command or symbol channel. Use ".cmd" and ".symbols"
+	as the new names.
+	* mainloop.c (init_stapio): Call init_ctl_channel(0);
+	* staprun.c (cleanup): Call stop_symbol_thread().
+	(main): Call start_symbol_thread().
+	* staprun_funcs.c (handle_symbols): Make a thread.
+	(start_symbol_thread): New.
+	(stop_symbol_thread): New.
+	
 2007-10-11  Frank Ch. Eigler  <fche@elastic.org>
 
 	* staprun.c (main): Move checks for init_cap and getuid
diff --git a/runtime/staprun/cap.c b/runtime/staprun/cap.c
index df4a7130..6f22dfc9 100644
--- a/runtime/staprun/cap.c
+++ b/runtime/staprun/cap.c
@@ -28,7 +28,7 @@
 		_perr(msg);					  \
 		exit(1);					  \
 	}							  \
-		
+
 /*
  * init_cap() sets up the initial capabilities for staprun. Then
  * it calls prctl( PR_SET_KEEPCAPS) to arrrange to keep these capabilities
@@ -57,7 +57,7 @@
 int init_cap(void)
 {
 	cap_t caps = cap_init();
-	cap_value_t capv[] = {CAP_SYS_MODULE, CAP_SYS_ADMIN, CAP_SYS_NICE, CAP_SETUID, CAP_SETGID};
+	cap_value_t capv[] = {CAP_SYS_MODULE, CAP_SYS_ADMIN, CAP_SYS_NICE, CAP_SETUID, CAP_SETGID, CAP_DAC_OVERRIDE};
 	const int numcaps = sizeof(capv) / sizeof(capv[0]);
 	uid_t uid = getuid();
 	gid_t gid = getgid();
diff --git a/runtime/staprun/ctl.c b/runtime/staprun/ctl.c
index 7fe57206..af7e6c1a 100644
--- a/runtime/staprun/ctl.c
+++ b/runtime/staprun/ctl.c
@@ -12,18 +12,23 @@
 
 #include "staprun.h"
 
-int init_ctl_channel(void)
+int init_ctl_channel(int symbols)
 {
-	char buf[PATH_MAX];
+	char *cname, buf[PATH_MAX];
 	struct statfs st;
 	int old_transport = 0;
+	
+	if (symbols)
+		cname = ".symbols";
+	else
+		cname = ".cmd";
 
  	if (statfs("/sys/kernel/debug", &st) == 0 && (int) st.f_type == (int) DEBUGFS_MAGIC) {
-		if (sprintf_chk(buf, "/sys/kernel/debug/systemtap/%s/cmd", modname))
+		if (sprintf_chk(buf, "/sys/kernel/debug/systemtap/%s/%s", modname, cname))
 			return -1;
 	} else {
 		old_transport = 1;
-		if (sprintf_chk(buf, "/proc/systemtap/%s/cmd", modname))
+		if (sprintf_chk(buf, "/proc/systemtap/%s/%s", modname, cname))
 			return -1;
 	}
 	
diff --git a/runtime/staprun/mainloop.c b/runtime/staprun/mainloop.c
index d919164f..c0722b56 100644
--- a/runtime/staprun/mainloop.c
+++ b/runtime/staprun/mainloop.c
@@ -164,7 +164,7 @@ int init_stapio(void)
 	dbug(2, "init_stapio\n");
 
 	/* create control channel */
-	use_old_transport = init_ctl_channel();
+	use_old_transport = init_ctl_channel(0);
 	if (use_old_transport < 0) {
 		err("Failed to initialize control channel.\n");
 		return -1;
diff --git a/runtime/staprun/staprun.c b/runtime/staprun/staprun.c
index 44ac0313..f4e67fdb 100644
--- a/runtime/staprun/staprun.c
+++ b/runtime/staprun/staprun.c
@@ -181,6 +181,8 @@ static void cleanup(int rc)
 	if (setpriority (PRIO_PROCESS, 0, 0) < 0)
 		_perr("setpriority");
 	
+	stop_symbol_thread();
+
 	/* rc == 2 means disconnected */
 	if (rc == 2)
 		return;
@@ -276,8 +278,7 @@ int main(int argc, char **argv)
 		exit(1);
 
 	setup_staprun_signals();
-	if (!attach_mod)
-		handle_symbols();
+	start_symbol_thread();
 
 	rc = run_stapio(argv);
 	cleanup(rc);
diff --git a/runtime/staprun/staprun.h b/runtime/staprun/staprun.h
index 685de294..c22cc4f3 100644
--- a/runtime/staprun/staprun.h
+++ b/runtime/staprun/staprun.h
@@ -35,12 +35,7 @@
 #include <linux/version.h>
 #include <sys/capability.h>
 
-#define DEBUG
-#ifdef DEBUG
 #define dbug(level, args...) {if (verbose>=level) {fprintf(stderr,"%s:%s:%d ",__name__,__FUNCTION__, __LINE__); fprintf(stderr,args);}}
-#else
-#define dbug(level, args...) ;
-#endif /* DEBUG */
 
 extern char *__name__;
 
@@ -125,7 +120,7 @@ int send_request(int type, void *data, int len);
 void cleanup_and_exit (int);
 int do_module(void *);
 void do_kernel_symbols(void);
-int init_ctl_channel(void);
+int init_ctl_channel(int);
 void close_ctl_channel(void);
 int init_relayfs(void);
 void close_relayfs(void);
@@ -145,7 +140,8 @@ int insert_module(const char *path, const char *special_options,
 	char **options);
 int mountfs(void);
 int check_permissions(void);
-void handle_symbols(void);
+void start_symbol_thread(void);
+void stop_symbol_thread(void);
 
 /* common.c functions */
 void parse_args(int argc, char **argv);
diff --git a/runtime/staprun/staprun_funcs.c b/runtime/staprun/staprun_funcs.c
index eec4ae63..86a72985 100644
--- a/runtime/staprun/staprun_funcs.c
+++ b/runtime/staprun/staprun_funcs.c
@@ -385,8 +385,10 @@ int check_permissions(void)
 	return check_path();
 }
 
-/* wait for symbol requests and reply */
-void handle_symbols(void)
+pthread_t symbol_thread_id = (pthread_t)0;
+
+/* Symbol handling thread */
+void *handle_symbols(void __attribute__((unused)) *arg)
 {
 	ssize_t nb;
 	void *data;
@@ -395,12 +397,6 @@ void handle_symbols(void)
 
 	dbug(2, "waiting for symbol requests\n");
 
-	/* create control channel */
-	if (init_ctl_channel() < 0) {
-		err("Failed to initialize control channel.\n");
-		exit(1);
-	}
-
 	while (1) { /* handle messages from control channel */
 		nb = read(control_channel, recvbuf, sizeof(recvbuf));
 		if (nb <= 0) {
@@ -417,7 +413,7 @@ void handle_symbols(void)
 		{
 			dbug(2, "STP_MODULES request received\n");
 			do_module(data);
-			goto done;
+			break;
 		}		
 		case STP_SYMBOLS:
 		{
@@ -439,6 +435,36 @@ void handle_symbols(void)
 			err("WARNING: ignored message of type %d\n", (type));
 		}
 	}
-done:
+
+	return NULL;
+}
+
+void start_symbol_thread(void)
+{
+	int status;
+
+	/* create symbol control channel */
+	status = do_cap(CAP_DAC_OVERRIDE, init_ctl_channel, 1);
+	drop_cap(CAP_DAC_OVERRIDE);
+	if (status < 0) {
+		err("Failed to initialize control channel.\n");
+		exit(1);
+	}
+	status = pthread_create(&symbol_thread_id, NULL, handle_symbols, NULL);
+	if (status) {
+		perr("Failed to create symbol thread.\n");
+		exit(1);
+	}
+}
+
+void stop_symbol_thread(void)
+{
+
+	if (symbol_thread_id) {
+		dbug(2, "Stopping symbol thread.\n");
+		pthread_cancel(symbol_thread_id);
+		pthread_join(symbol_thread_id, NULL);
+	}
 	close_ctl_channel();
 }
+
diff --git a/runtime/staprun/symbols.c b/runtime/staprun/symbols.c
index 61b56b2e..315362fa 100644
--- a/runtime/staprun/symbols.c
+++ b/runtime/staprun/symbols.c
@@ -140,7 +140,10 @@ err0:
 }
 #undef SECDIR
 
-void send_module (char *mname)
+/* 
+ * For modules, we send the name, section names, and offsets
+ */
+static void send_module (char *mname)
 {
 	char data[32768];
 	int len = get_sections(mname, data, sizeof(data));
@@ -152,6 +155,9 @@ void send_module (char *mname)
 	}
 }
 
+/*
+ * Send either all modules, or a specific one.
+ */
 int do_module (void *data)
 {
 	struct _stp_module *mod = (struct _stp_module *)data;
@@ -183,6 +189,11 @@ static int compar(const void *p1, const void *p2)
 
 #define MAX_SYMBOLS 32*1024
 
+/*
+ * Read /proc/kallsyms and send all kernel symbols to the
+ * systemtap module.  Ignore module symbols; the systemtap module
+ * can access them directly.
+ */
 void do_kernel_symbols(void)
 {
 	FILE *kallsyms=NULL;