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Stop threads when attaching to a PID that is the tgid.

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This commit is contained in:
Luis Machado 2011-08-24 12:17:39 +00:00
parent 13da1c9782
commit e3deef738c
3 changed files with 87 additions and 4 deletions
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8
gdb/gdbserver/ChangeLog
View file

@ -1,3 +1,11 @@
2011-08-24 Luis Machado <lgustavo@codesourcery.com>
* linux-low.c: Include linux-procfs.h.
(linux_attach_lwp_1): Update comments.
(linux_attach): Scan for existing threads when attaching to a
process that is the tgid.
* Makefile.in: Update dependencies.
2011-08-24 Luis Machado <lgustavo@codesourcery.com>
* configure.srv: Add linux-procfs.o dependencies.

8
gdb/gdbserver/Makefile.in
View file

@ -354,6 +354,8 @@ linux_ptrace_h = $(srcdir)/../common/linux-ptrace.h
gdb_thread_db_h = $(srcdir)/../common/gdb_thread_db.h
linux_procfs_h = $(srcdir)/../common/linux-procfs.h
lynx_low_h = $(srcdir)/lynx-low.h $(srcdir)/server.h
nto_low_h = $(srcdir)/nto-low.h
@ -405,6 +407,9 @@ gdbreplay.o: gdbreplay.c config.h
signals.o: ../common/signals.c $(server_h) $(signals_def)
$(CC) -c $(CPPFLAGS) $(INTERNAL_CFLAGS) $< -DGDBSERVER
linux-procfs.o: ../common/linux-procfs.c $(server_h)
$(CC) -c $(CPPFLAGS) $(INTERNAL_CFLAGS) $< -DGDBSERVER
common-utils.o: ../common/common-utils.c $(server_h)
$(CC) -c $(CPPFLAGS) $(INTERNAL_CFLAGS) $< -DGDBSERVER
@ -443,7 +448,8 @@ i386-low.o: i386-low.c $(i386_low_h) $(server_h) $(target_h)
i387-fp.o: i387-fp.c $(server_h)
linux-low.o: linux-low.c $(linux_low_h) $(linux_ptrace_h) $(server_h) $(linux_osdata_h)
linux-low.o: linux-low.c $(linux_low_h) $(linux_ptrace_h) $(linux_procfs_h) \
$(server_h) $(linux_osdata_h)
$(CC) -c $(CPPFLAGS) $(INTERNAL_CFLAGS) $< @USE_THREAD_DB@
linux-arm-low.o: linux-arm-low.c $(linux_low_h) $(server_h) \

75
gdb/gdbserver/linux-low.c
View file

@ -26,6 +26,7 @@
#include <sys/param.h>
#include <sys/ptrace.h>
#include "linux-ptrace.h"
#include "linux-procfs.h"
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>
@ -586,7 +587,9 @@ linux_attach_lwp_1 (unsigned long lwpid, int initial)
}
if (initial)
/* NOTE/FIXME: This lwp might have not been the tgid. */
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
@ -621,8 +624,10 @@ linux_attach_lwp_1 (unsigned long lwpid, int initial)
In this case we want the process thread to stop.
This is handled by having linux_attach set last_resume_kind ==
resume_stop after we return.
??? If the process already has several threads we leave the other
threads running.
If the pid we are attaching to is also the tgid, we attach to and
stop all the existing threads. Otherwise, we attach to pid and
ignore any other threads in the same group as this pid.
3) GDB is connecting to gdbserver and is requesting an enumeration of all
existing threads.
@ -646,9 +651,14 @@ linux_attach_lwp (unsigned long lwpid)
linux_attach_lwp_1 (lwpid, 0);
}
/* Attach to PID. If PID is the tgid, attach to it and all
of its threads. */
int
linux_attach (unsigned long pid)
{
/* Attach to PID. We will check for other threads
soon. */
linux_attach_lwp_1 (pid, 1);
linux_add_process (pid, 1);
@ -662,6 +672,65 @@ linux_attach (unsigned long pid)
thread->last_resume_kind = resume_stop;
}
if (linux_proc_get_tgid (pid) == pid)
{
DIR *dir;
char pathname[128];
sprintf (pathname, "/proc/%ld/task", pid);
dir = opendir (pathname);
if (!dir)
{
fprintf (stderr, "Could not open /proc/%ld/task.\n", pid);
fflush (stderr);
}
else
{
/* At this point we attached to the tgid. Scan the task for
existing threads. */
unsigned long lwp;
int new_threads_found;
int iterations = 0;
struct dirent *dp;
while (iterations < 2)
{
new_threads_found = 0;
/* Add all the other threads. While we go through the
threads, new threads may be spawned. Cycle through
the list of threads until we have done two iterations without
finding new threads. */
while ((dp = readdir (dir)) != NULL)
{
/* Fetch one lwp. */
lwp = strtoul (dp->d_name, NULL, 10);
/* Is this a new thread? */
if (lwp
&& find_thread_ptid (ptid_build (pid, lwp, 0)) == NULL)
{
linux_attach_lwp_1 (lwp, 0);
new_threads_found++;
if (debug_threads)
fprintf (stderr, "\
Found and attached to new lwp %ld\n", lwp);
}
}
if (!new_threads_found)
iterations++;
else
iterations = 0;
rewinddir (dir);
}
closedir (dir);
}
}
return 0;
}