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The test-case gdb.threads/signal-sigtrap.exp:
- installs a signal handler called sigtrap_handler for SIGTRAP,
- sets a breakpoint on sigtrap_handler, and
- expects the breakpoint to trigger after issuing "signal SIGTRAP".
Usually, that happens indeed:
...
(gdb) signal SIGTRAP^M
Continuing with signal SIGTRAP.^M
^M
Thread 1 "signal-sigtrap" hit Breakpoint 2, sigtrap_handler (sig=5)^M
28 }^M
(gdb) PASS: $exp: sigtrap thread 1: signal SIGTRAP reaches handler
...
Occasionally, I run into this failure on openSUSE Tumbleweed:
...
(gdb) signal SIGTRAP^M
Continuing with signal SIGTRAP.^M
^M
Thread 1 "signal-sigtrap" received signal SIGTRAP, Trace/breakpoint trap.^M
__pthread_create_2_1 () at pthread_create.c:843^M
(gdb) FAIL: $exp: sigtrap thread 1: signal SIGTRAP reaches handler
...
AFAIU, the problem is in the situation that is setup before issuing that
command, by running to a breakpoint in thread_function:
...
void *thread_function (void *arg) {
return NULL;
}
int main (void) {
pthread_t child_thread;
signal (SIGTRAP, sigtrap_handler);
pthread_create (&child_thread, NULL, thread_function, NULL);
pthread_join (child_thread, NULL);
return 0;
}
...
In the passing case, thread 2 is stopped in thread_function, and thread 1 is
stopped somewhere in pthread_join:
...
(gdb) info threads^M
Id Target Id Frame ^M
1 Thread ... (LWP ...) "signal-sigtrap" __futex_abstimed_wait_common64 ()
* 2 Thread ... (LWP ...) "signal-sigtrap" thread_function ()
...
In the failing case, thread 2 is stopped in thread_function, but thread 1 is
stopped somewhere in pthread_create:
...
(gdb) info threads^M
Id Target Id Frame ^M
1 Thread ... (LWP ...) "signal-sigtrap" __GI___clone3 ()
* 2 Thread ... (LWP ...) "signal-sigtrap" thread_function ()
...
What I think happens is that pthread_create blocks SIGTRAP at some point, and
if the "signal SIGTRAP" command is issued while that is the case, the signal
becomes pending and consequently there's no longer a guarantee that the signal
will be delivered to the inferior.
Instead the signal will be handled by gdb like this:
...
(gdb) info signals SIGTRAP
Signal Stop Print Pass to program Description
SIGTRAP Yes Yes No Trace/breakpoint trap
...
Fix this by adding a barrier that ensures that pthread_create is done before
we issue the "signal SIGTRAP" command.
Likewise in test-case gdb.threads/signal-command-handle-nopass.exp.
Using the fixed test-case, I tested my theory by explicitly blocking SIGTRAP:
...
+ sigset_t old_ss, new_ss;
+ sigemptyset (&new_ss);
+ sigaddset (&new_ss, SIGTRAP);
+ sigprocmask (SIG_BLOCK, &new_ss, &old_ss);
+
/* Make sure that pthread_create is done once the breakpoint on
thread_function triggers. */
pthread_barrier_wait (&barrier);
pthread_join (child_thread, NULL);
+ sigprocmask (SIG_SETMASK, &old_ss, NULL);
...
and managed to reproduce the same failure:
...
(gdb) signal SIGTRAP^M
Continuing with signal SIGTRAP.^M
[Thread 0x7ffff7c00700 (LWP 13254) exited]^M
^M
Thread 1 "signal-sigtrap" received signal SIGTRAP, Trace/breakpoint trap.^M
0x00007ffff7c80056 in __GI___sigprocmask () sigprocmask.c:39^M
(gdb) FAIL: $exp: sigtrap thread 1: signal SIGTRAP reaches handler
...
Tested on x86_64-linux.
PR testsuite/26867
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=26867
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This commit is the result of the following actions:
- Running gdb/copyright.py to update all of the copyright headers to
include 2024,
- Manually updating a few files the copyright.py script told me to
update, these files had copyright headers embedded within the
file,
- Regenerating gdbsupport/Makefile.in to refresh it's copyright
date,
- Using grep to find other files that still mentioned 2023. If
these files were updated last year from 2022 to 2023 then I've
updated them this year to 2024.
I'm sure I've probably missed some dates. Feel free to fix them up as
you spot them.
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This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
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This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
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This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
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gdb/ChangeLog:
Update copyright year range in all GDB files.
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This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update copyright year range in all GDB files
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This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
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gdb/ChangeLog:
Update year range in copyright notice of all files.
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Some local changes I was working on related to SIGTRAP handling
resulted in "signal SIGTRAP" no longer passing the SIGTRAP to the
inferior.
Surprisingly, only annota1.exp catches this. This commit adds a test
that doesn't rely on annotations, so that at the point annotations are
finaly dropped, we still have this use case covered ...
This is a multi-threaded test to also exercise the case of first
needing to do a step-over before delivering the signal.
Tested on x86_64 Fedora 20, native, remote/extended-remote gdbserver.
gdb/testsuite/
2015-02-10 Pedro Alves <palves@redhat.com>
* gdb.threads/signal-sigtrap.c: New file.
* gdb.threads/signal-sigtrap.exp: New file.
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