From: Tom de Vries <tdevries@suse.de>
To: gdb-patches@sourceware.org
Cc: Pedro Alves <pedro@palves.net>, Tom Tromey <tom@tromey.com>
Subject: [PATCH][gdb] Block SIGTERM in worker threads
Date: Thu, 30 Jun 2022 11:58:31 +0200 [thread overview]
Message-ID: <20220630095824.GA24025@delia.home> (raw)
Hi,
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.
Any comments?
Thanks,
- Tom
[gdb] Block SIGTERM in worker threads
---
gdbsupport/block-signals.h | 1 +
1 file changed, 1 insertion(+)
diff --git a/gdbsupport/block-signals.h b/gdbsupport/block-signals.h
index cf97208c750..4703690a4ec 100644
--- a/gdbsupport/block-signals.h
+++ b/gdbsupport/block-signals.h
@@ -42,6 +42,7 @@ class block_signals
sigaddset (&mask, SIGCHLD);
sigaddset (&mask, SIGALRM);
sigaddset (&mask, SIGWINCH);
+ sigaddset (&mask, SIGTERM);
gdb_sigmask (SIG_BLOCK, &mask, &m_old_mask);
#endif
}
next reply other threads:[~2022-06-30 9:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-30 9:58 Tom de Vries [this message]
2022-06-30 11:08 ` Pedro Alves
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