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* [binutils-gdb] gdb: Reorganize linux_nat_filter_event
@ 2022-03-10 11:41 Pedro Alves
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From: Pedro Alves @ 2022-03-10 11:41 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1abeb1e90d708c1d94867957f90607eaa63dfad7
commit 1abeb1e90d708c1d94867957f90607eaa63dfad7
Author: Pedro Alves <pedro@palves.net>
Date: Mon Feb 21 20:07:20 2022 +0000
gdb: Reorganize linux_nat_filter_event
Reorganize linux-nat.c:linux_nat_filter_event such that all the
handling for events for LWPs not in the LWP list is together. This
helps make a following patch clearer. The comments and debug messages
have also been tweaked - the end goal is to have them synchronized
with the gdbserver counterpart.
Change-Id: I8586d8dcd76d8bd3795145e3056fc660e3b2cd22
Diff:
---
gdb/linux-nat.c | 75 ++++++++++++++++++++++++++++++---------------------------
1 file changed, 40 insertions(+), 35 deletions(-)
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index 13682fcff43..1555d3a79e3 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -2776,46 +2776,51 @@ linux_nat_filter_event (int lwpid, int status)
lp = find_lwp_pid (ptid_t (lwpid));
- /* Check for stop events reported by a process we didn't already
- know about - anything not already in our LWP list.
-
- If we're expecting to receive stopped processes after
- fork, vfork, and clone events, then we'll just add the
- new one to our list and go back to waiting for the event
- to be reported - the stopped process might be returned
- from waitpid before or after the event is.
-
- But note the case of a non-leader thread exec'ing after the
- leader having exited, and gone from our lists. The non-leader
- thread changes its tid to the tgid. */
-
- if (WIFSTOPPED (status) && lp == NULL
- && (WSTOPSIG (status) == SIGTRAP && event == PTRACE_EVENT_EXEC))
+ /* Check for events reported by anything not in our LWP list. */
+ if (lp == nullptr)
{
- /* A multi-thread exec after we had seen the leader exiting. */
- linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid);
+ if (WIFSTOPPED (status))
+ {
+ if (WSTOPSIG (status) == SIGTRAP && event == PTRACE_EVENT_EXEC)
+ {
+ /* A non-leader thread exec'ed after we've seen the
+ leader zombie, and removed it from our lists (in
+ check_zombie_leaders). The non-leader thread changes
+ its tid to the tgid. */
+ linux_nat_debug_printf
+ ("Re-adding thread group leader LWP %d after exec.",
+ lwpid);
- lp = add_lwp (ptid_t (lwpid, lwpid));
- lp->stopped = 1;
- lp->resumed = 1;
- add_thread (linux_target, lp->ptid);
- }
+ lp = add_lwp (ptid_t (lwpid, lwpid));
+ lp->stopped = 1;
+ lp->resumed = 1;
+ add_thread (linux_target, lp->ptid);
+ }
+ else
+ {
+ /* A process we are controlling has forked and the new
+ child's stop was reported to us by the kernel. Save
+ its PID and go back to waiting for the fork event to
+ be reported - the stopped process might be returned
+ from waitpid before or after the fork event is. */
+ linux_nat_debug_printf
+ ("Saving LWP %d status %s in stopped_pids list",
+ lwpid, status_to_str (status).c_str ());
+ add_to_pid_list (&stopped_pids, lwpid, status);
+ }
+ }
+ else
+ {
+ /* Don't report an event for the exit of an LWP not in our
+ list, i.e. not part of any inferior we're debugging.
+ This can happen if we detach from a program we originally
+ forked and then it exits. */
+ }
- if (WIFSTOPPED (status) && !lp)
- {
- linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
- (long) lwpid, status_to_str (status).c_str ());
- add_to_pid_list (&stopped_pids, lwpid, status);
- return;
+ if (lp == nullptr)
+ return;
}
- /* Make sure we don't report an event for the exit of an LWP not in
- our list, i.e. not part of the current process. This can happen
- if we detach from a program we originally forked and then it
- exits. */
- if (!WIFSTOPPED (status) && !lp)
- return;
-
/* This LWP is stopped now. (And if dead, this prevents it from
ever being continued.) */
lp->stopped = 1;
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