Re: [rfa] Include the LWP in thread-db's PTIDs

[Daniel Jacobowitz <drow@false.org>]

On Sun, Oct 10, 2004 at 05:36:30PM -0400, Daniel Jacobowitz wrote:
> At one time, I believe that thread-db.c was planned to support the full
> range of features supported by the libthread_db interface, presumably as
> defined by Sun's implementation.  That never panned out, and while non-1:1
> support did work at one point, I don't think it has in a long while.  If it
> was wanted, I wouldn't re-implement it the same way.  So this patch begins
> the process of removing unneeded generality from thread-db.  In particular,
> while thread-db will still compute the TID, the mapping of threads to LWPs
> will be considered fixed.
> 
> My goal is to have a GNU/Linux target vector, whose entry points call into
> thread-db when necessary, instead of having a thread-db wrapper around all
> the GNU/Linux methods.  One of the things this will fix is the need for two
> separate versions of the GNU/Linux native wait() code - we will always use
> the multi-threaded-aware version.  Another thing it will fix is a bug in the
> fork-following code which tries to find the LWP from a thread ID.
> 
> This patch tested on i686-pc-linux-gnu using NPTL; no regressions. OK?

Here's the patch, updated to apply to linux-thread-db.c instead.  Still
no regressions; Mark indicated that the 1:1 assumption seemed reasonable
once the file was marked as Linux-specific.

Michael, OK to commit?

-- 
Daniel Jacobowitz

2004-11-14  Daniel Jacobowitz  <dan@debian.org>

	* linux-thread-db.c (BUILD_THREAD): Delete.
	(thread_get_info_callback): Include LWP ID in thread ID.
	(thread_from_lwp, check_event, find_new_threads_callback): Likewise.
	(lwp_from_thread): Use the LWP ID from the thread ID.

Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/thread-db.c,v
retrieving revision 1.46
diff -u -p -r1.46 thread-db.c
--- linux-thread-db.c	8 Oct 2004 20:29:56 -0000	1.46
+++ linux-thread-db.c	10 Oct 2004 21:23:44 -0000
@@ -143,7 +143,6 @@ static void detach_thread (ptid_t ptid, 
 #define is_thread(ptid)		(GET_THREAD (ptid) != 0)
 
 #define BUILD_LWP(lwp, pid)	ptid_build (pid, lwp, 0)
-#define BUILD_THREAD(tid, pid)	ptid_build (pid, 0, tid)
 \f
 
 /* Use "struct private_thread_info" to cache thread state.  This is
@@ -267,7 +266,7 @@ thread_get_info_callback (const td_thrha
 	   thread_db_err_str (err));
 
   /* Fill the cache.  */
-  thread_ptid = BUILD_THREAD (ti.ti_tid, GET_PID (inferior_ptid));
+  thread_ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, ti.ti_tid);
   thread_info = find_thread_pid (thread_ptid);
 
   /* In the case of a zombie thread, don't continue.  We don't want to
@@ -385,22 +384,14 @@ thread_from_lwp (ptid_t ptid)
 
   gdb_assert (thread_info && thread_info->private->ti_valid);
 
-  return BUILD_THREAD (thread_info->private->ti.ti_tid, GET_PID (ptid));
+  return ptid_build (GET_PID (ptid), GET_LWP (ptid),
+		     thread_info->private->ti.ti_tid);
 }
 
 static ptid_t
 lwp_from_thread (ptid_t ptid)
 {
-  struct thread_info *thread_info;
-  ptid_t thread_ptid;
-
-  if (!is_thread (ptid))
-    return ptid;
-
-  thread_info = find_thread_pid (ptid);
-  thread_db_get_info (thread_info);
-
-  return BUILD_LWP (thread_info->private->ti.ti_lid, GET_PID (ptid));
+  return BUILD_LWP (GET_LWP (ptid), GET_PID (ptid));
 }
 \f
 
@@ -903,7 +894,7 @@ check_event (ptid_t ptid)
       if (err != TD_OK)
 	error ("Cannot get thread info: %s", thread_db_err_str (err));
 
-      ptid = BUILD_THREAD (ti.ti_tid, GET_PID (ptid));
+      ptid = ptid_build (GET_PID (ptid), ti.ti_lid, ti.ti_tid);
 
       switch (msg.event)
 	{
@@ -1175,7 +1166,7 @@ find_new_threads_callback (const td_thrh
   if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
     return 0;			/* A zombie -- ignore.  */
 
-  ptid = BUILD_THREAD (ti.ti_tid, GET_PID (inferior_ptid));
+  ptid = ptid_build (GET_PID (inferior_ptid), ti.ti_lid, ti.ti_tid);
 
   if (!in_thread_list (ptid))
     attach_thread (ptid, th_p, &ti, 1);