143 lines
4.6 KiB
Diff
143 lines
4.6 KiB
Diff
2007-07-08 Jan Kratochvil <jan.kratochvil@redhat.com>
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* linux-nat.c (linux_lwp_is_zombie): New function.
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(wait_lwp): Fix lockup on exit of the thread group leader.
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(linux_xfer_partial): Renamed to ...
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(linux_xfer_partial_lwp): ... here.
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(linux_xfer_partial): New function wrapping LINUX_XFER_PARTIAL_LWP.
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2008-02-24 Jan Kratochvil <jan.kratochvil@redhat.com>
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Port to GDB-6.8pre.
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Index: gdb-6.8.50.20081209/gdb/linux-nat.c
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===================================================================
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--- gdb-6.8.50.20081209.orig/gdb/linux-nat.c 2008-12-10 01:27:34.000000000 +0100
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+++ gdb-6.8.50.20081209/gdb/linux-nat.c 2008-12-10 01:28:14.000000000 +0100
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@@ -1981,6 +1981,31 @@ linux_handle_extended_wait (struct lwp_i
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_("unknown ptrace event %d"), event);
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}
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+static int
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+linux_lwp_is_zombie (long lwp)
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+{
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+ char buffer[MAXPATHLEN];
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+ FILE *procfile;
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+ int retval = 0;
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+
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+ sprintf (buffer, "/proc/%ld/status", lwp);
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+ procfile = fopen (buffer, "r");
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+ if (procfile == NULL)
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+ {
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+ warning (_("unable to open /proc file '%s'"), buffer);
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+ return 0;
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+ }
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+ while (fgets (buffer, sizeof (buffer), procfile) != NULL)
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+ if (strcmp (buffer, "State:\tZ (zombie)\n") == 0)
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+ {
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+ retval = 1;
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+ break;
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+ }
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+ fclose (procfile);
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+
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+ return retval;
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+}
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+
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/* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
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exited. */
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@@ -1988,16 +2013,31 @@ static int
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wait_lwp (struct lwp_info *lp)
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{
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pid_t pid;
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- int status;
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+ int status = 0;
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int thread_dead = 0;
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gdb_assert (!lp->stopped);
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gdb_assert (lp->status == 0);
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- pid = my_waitpid (GET_LWP (lp->ptid), &status, 0);
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- if (pid == -1 && errno == ECHILD)
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+ /* Thread group leader may have exited but we would lock up by WAITPID as it
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+ waits on all its threads; __WCLONE is not applicable for the leader.
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+ The thread leader restrictions is only a performance optimization here.
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+ LINUX_NAT_THREAD_ALIVE cannot be used here as it requires a STOPPED
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+ process; it gets ESRCH both for the zombie and for running processes. */
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+ if (is_lwp (lp->ptid) && GET_PID (lp->ptid) == GET_LWP (lp->ptid)
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+ && linux_lwp_is_zombie (GET_LWP (lp->ptid)))
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+ {
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+ thread_dead = 1;
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+ if (debug_linux_nat)
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+ fprintf_unfiltered (gdb_stdlog, "WL: Threads leader %s vanished.\n",
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+ target_pid_to_str (lp->ptid));
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+ }
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+
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+ if (!thread_dead)
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{
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- pid = my_waitpid (GET_LWP (lp->ptid), &status, __WCLONE);
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+ pid = my_waitpid (GET_LWP (lp->ptid), &status, 0);
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+ if (pid == -1 && errno == ECHILD)
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+ pid = my_waitpid (GET_LWP (lp->ptid), &status, __WCLONE);
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if (pid == -1 && errno == ECHILD)
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{
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/* The thread has previously exited. We need to delete it
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@@ -4153,8 +4193,10 @@ linux_nat_xfer_osdata (struct target_ops
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return len;
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}
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+/* Transfer from the specific LWP currently set by PID of INFERIOR_PTID. */
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+
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static LONGEST
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-linux_xfer_partial (struct target_ops *ops, enum target_object object,
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+linux_xfer_partial_lwp (struct target_ops *ops, enum target_object object,
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const char *annex, gdb_byte *readbuf,
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const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
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{
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@@ -4201,6 +4243,45 @@ linux_xfer_partial (struct target_ops *o
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offset, len);
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}
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+/* nptl_db expects being able to transfer memory just by specifying PID.
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+ After the thread group leader exists the Linux kernel turns the task
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+ into zombie no longer permitting accesses to its memory.
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+ Transfer the memory from an arbitrary LWP_LIST entry in such case. */
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+
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+static LONGEST
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+linux_xfer_partial (struct target_ops *ops, enum target_object object,
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+ const char *annex, gdb_byte *readbuf,
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+ const gdb_byte *writebuf, ULONGEST offset, LONGEST len)
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+{
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+ LONGEST xfer;
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+ struct lwp_info *lp;
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+ /* Not using SAVE_INFERIOR_PTID already here for better performance. */
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+ struct cleanup *old_chain = NULL;
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+ ptid_t inferior_ptid_orig = inferior_ptid;
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+
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+ errno = 0;
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+ xfer = linux_xfer_partial_lwp (ops, object, annex, readbuf, writebuf,
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+ offset, len);
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+
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+ for (lp = lwp_list; xfer == 0 && (errno == EACCES || errno == ESRCH)
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+ && lp != NULL; lp = lp->next)
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+ {
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+ if (!is_lwp (lp->ptid) || ptid_equal (lp->ptid, inferior_ptid_orig))
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+ continue;
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+
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+ if (old_chain == NULL)
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+ old_chain = save_inferior_ptid ();
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+ inferior_ptid = BUILD_LWP (GET_LWP (lp->ptid), GET_LWP (lp->ptid));
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+ errno = 0;
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+ xfer = linux_xfer_partial_lwp (ops, object, annex, readbuf, writebuf,
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+ offset, len);
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+ }
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+
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+ if (old_chain != NULL)
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+ do_cleanups (old_chain);
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+ return xfer;
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+}
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+
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/* Create a prototype generic GNU/Linux target. The client can override
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it with local methods. */
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