Re: [PATCH 1/2] [gdb/testsuite] Fix race in gdb.threads/leader-exit.exp

[Keith Seitz <keiths@redhat.com>]

Hi,

On 7/23/26 4:40 AM, Tom de Vries wrote:
> 
> The problem is that after the pthread_join is executed:
> ...
>    i = pthread_join (main_thread, NULL);
>    ...
> 
>    sleep (10);  /* break-here */
> ...
> there's a race between:
> - the breakpoint at break-here triggering, and
> - the "Thread exited" message for the main thread being reported.

While I cannot reproduce this on my local hardware, your analysis
is sound.

> Fix this by:
> - adding a loop before the break location
> - waiting in the loop until the "Thread exited" message is seen
> - sending ^C to get a prompt
> - setting a variable to exit the loop
> 
> Likewise in gdb.threads/non-ldr-exc-2.exp.

Sounds like a plan!

> diff --git a/gdb/testsuite/gdb.threads/leader-exit.exp b/gdb/testsuite/gdb.threads/leader-exit.exp
> index b5e6f558ac7..22f27d2d6e8 100644
> --- a/gdb/testsuite/gdb.threads/leader-exit.exp
> +++ b/gdb/testsuite/gdb.threads/leader-exit.exp
> @@ -30,6 +30,28 @@ if {![runto_main]} {
>       return
>   }
>   
> +# Wait for the "Thread exited" message.
> +set re_thread_exited {\[Thread [^\r\n]+ exited\]}
> +set saw_thread_exited 0
> +gdb_test_multiple "continue" "continue to thread exited" {
> +    -re $re_thread_exited {
> +	set saw_thread_exited 1
> +	# Get a prompt.
> +	send_gdb "\003"
> +	exp_continue
> +    }
> +    -re -wrap "" {
> +	pass $gdb_test_name
> +    }
> +}
> +gdb_assert {$saw_thread_exited} "thread exited"
> +if {!$saw_thread_exited} {
> +    return
> +}
> +
> +# Let the inferior to exit the wait_for_exit loop.

This comment got a bit jumbled. Superfluous "to"?

> +gdb_test_no_output "set var wait_for_exit = 0"
> +
>   gdb_breakpoint [gdb_get_line_number "break-here"]
>   gdb_continue_to_breakpoint "break-here" ".* break-here .*"
>   
> diff --git a/gdb/testsuite/gdb.threads/non-ldr-exc-2.exp b/gdb/testsuite/gdb.threads/non-ldr-exc-2.exp
> index ead262cc2b5..dfc34f42afe 100644
> --- a/gdb/testsuite/gdb.threads/non-ldr-exc-2.exp
> +++ b/gdb/testsuite/gdb.threads/non-ldr-exc-2.exp
> @@ -37,6 +37,28 @@ proc do_test { lock_sched nonstop } {
>   	return -1
>       }
>   
> +    # Wait for the "Thread exited" message.
> +    set re_thread_exited {\[Thread [^\r\n]+ exited\]}
> +    set saw_thread_exited 0
> +    gdb_test_multiple "continue" "continue to thread exited" {
> +	-re $re_thread_exited {
> +	    set saw_thread_exited 1
> +	    # Get a prompt.
> +	    send_gdb "\003"
> +	    exp_continue
> +	}
> +	-re -wrap "" {
> +	    pass $gdb_test_name
> +	}
> +    }
> +    gdb_assert {$saw_thread_exited} "thread exited"
> +    if {!$saw_thread_exited} {
> +	return
> +    }
> +
> +    # Let the inferior to exit the wait_for_exit loop.

Same nit in this comment.

Question: Since this test file now relies on sending the target
an interrupt, does it also need the same "require" on gdb,nointerrupts
that leader-exit.exp has?

Reviewed-By: Keith Seitz <keiths@redhat.com>

Keith

> +    gdb_test_no_output "set var wait_for_exit = 0"
> +
>       gdb_breakpoint [gdb_get_line_number "break-here"]
>       gdb_continue_to_breakpoint "break-here" ".* break-here .*"
>