4ece39c56c
I ran into the following FAIL: ... (gdb) python kill_and_detach()^M Traceback (most recent call last):^M File "<string>", line 1, in <module>^M File "<string>", line 7, in kill_and_detach^M gdb.error: Selected thread is running.^M Error while executing Python code.^M (gdb) FAIL: gdb.base/kill-during-detach.exp: exit_p=true: checkpoint_p=true: \ python kill_and_detach() ... The FAIL happens as follows: - gdb is debugging a process A - a checkpoint is created, in other words, fork is called in the inferior, after which we have: - checkpoint 0 (the fork parent, process A), and - checkpoint 1 (the fork child, process B). - during checkpoint creation, lseek is called in the inferior (process A) for all file descriptors, and it returns != -1 for at least one file descriptor. - the process A continues in the background - gdb detaches, from process A - gdb switches to process B, in other words, it restarts checkpoint 1 - while restarting checkpoint 1, gdb tries to call lseek in the inferior (process B), but this fails because gdb incorrectly thinks that inferior B is running. This happens because linux_nat_switch_fork patches the pid of process B into the current inferior and current thread which where originally representing process A. So, because process A was running in the background, the thread_info fields executing and resumed are set accordingly, but they are not correct for process B. There's a line in fork_load_infrun_state that fixes up the thread_info field stop_pc, so fix this by adding similar fixups for the executing and resumed fields alongside. The FAIL did not always reproduce, so extend the test-case to reliably trigger this scenario. Tested on x86_64-linux. Approved-By: Kevin Buettner <kevinb@redhat.com> PR gdb/31203 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31203
61 lines
1.6 KiB
C
61 lines
1.6 KiB
C
/* This testcase is part of GDB, the GNU debugger.
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Copyright 2023 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <unistd.h>
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#include <stdio.h>
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#include <assert.h>
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volatile int dont_exit_just_yet = 1;
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#define XSTR(s) STR(s)
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#define STR(s) #s
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volatile int with_checkpoint = 0;
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int
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main ()
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{
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alarm (300);
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if (with_checkpoint)
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{
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/* We open a file and move file pos from 0 to 1. We set the checkpoint
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when pos is 0, and restart it when pos is 1. This makes sure that
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restarting the checkpoint excercises calling lseek in the
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inferior. */
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/* Open a file. */
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const char *filename = XSTR (BINFILE);
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FILE *fp = fopen (filename, "r");
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volatile int checkpoint_here = 0; /* Checkpoint here. */
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if (fp != NULL)
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{
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/* Move file pos from 0 to 1. */
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int res = fseek (fp, 1, SEEK_SET);
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assert (res == 0);
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}
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}
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/* Spin until GDB releases us. */
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while (dont_exit_just_yet)
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usleep (100000);
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_exit (0);
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}
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