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With gdb build with gcc-12 and -fsanitize=thread, and test-case gdb.base/gdb-sigterm.exp, I run into: ... WARNING: ThreadSanitizer: data race (pid=9722)^M Write of size 4 at 0x00000325bc68 by thread T1:^M #0 handle_sigterm(int) src/gdb/event-top.c:1211 (gdb+0x8ec01f)^M ... Previous read of size 4 at 0x00000325bc68 by main thread:^M [failed to restore the stack]^M ^M Location is global 'sync_quit_force_run' of size 4 at \ 0x00000325bc68 (gdb+0x325bc68)^M ... SUMMARY: ThreadSanitizer: data race gdb/event-top.c:1211 in \ handle_sigterm(int)^M ... and 3 more data races involving handle_sigterm and locations: - active_ext_lang - quit_flag - heap block of size 40 (XNEW (async_signal_handler) in create_async_signal_handler) This was reported in PR29297. The testcase executes a "kill -TERM $gdb_pid", which generates a process-directed signal. A process-directed signal can be delivered to any thread, and what we see here is the fallout of the signal being delivered to a worker thread rather than the main thread. Fix this by blocking SIGTERM in the worker threads. [ I have not been able to reproduce this after it occurred for the first time, so unfortunately I cannot confirm that the patch fixes the problem. ] Tested on x86_64-linux, with and without -fsanitize=thread. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29297
69 lines
1.7 KiB
C++
69 lines
1.7 KiB
C++
/* Block signals used by gdb
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Copyright (C) 2019-2022 Free Software Foundation, Inc.
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This file is part of GDB.
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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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#ifndef GDBSUPPORT_BLOCK_SIGNALS_H
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#define GDBSUPPORT_BLOCK_SIGNALS_H
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#include <signal.h>
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#include "gdbsupport/gdb-sigmask.h"
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namespace gdb
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{
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/* This is an RAII class that temporarily blocks the signals needed by
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gdb. This can be used before starting a new thread to ensure that
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this thread starts with the appropriate signals blocked. */
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class block_signals
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{
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public:
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block_signals ()
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{
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#ifdef HAVE_SIGPROCMASK
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sigset_t mask;
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sigemptyset (&mask);
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sigaddset (&mask, SIGINT);
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sigaddset (&mask, SIGCHLD);
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sigaddset (&mask, SIGALRM);
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sigaddset (&mask, SIGWINCH);
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sigaddset (&mask, SIGTERM);
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gdb_sigmask (SIG_BLOCK, &mask, &m_old_mask);
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#endif
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}
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~block_signals ()
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{
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#ifdef HAVE_SIGPROCMASK
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gdb_sigmask (SIG_SETMASK, &m_old_mask, nullptr);
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#endif
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}
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DISABLE_COPY_AND_ASSIGN (block_signals);
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private:
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#ifdef HAVE_SIGPROCMASK
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sigset_t m_old_mask;
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#endif
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};
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}
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#endif /* GDBSUPPORT_BLOCK_SIGNALS_H */
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