[PING][RFC][gdb/testsuite] Fix inferior pid in gdb.server/server-kill.exp

[Tom de Vries <tdevries@suse.de>]

On 10/11/22 16:01, Tom de Vries wrote:
> Hi,
> 
> Consider this patch in gdb.server/server-kill.exp:
> ...
>   proc kill_server {} {
>       global server_pid
> 
> +    remote_exec target "pstree -a -p $server_pid"
>       remote_exec target "kill -9 $server_pid"
>   }
> ...
> 
> We have for kill_pid_of=server, as expected, the gdbserver killed:
> ...
> Executing on target: pstree -a -p 6969    (timeout = 300)
> builtin_spawn -ignore SIGHUP pstree -a -p 6969^M
> gdbserver,6969^M
>    `-server-kill,6976^M
> Executing on target: kill -9 6969    (timeout = 300)
> builtin_spawn -ignore SIGHUP kill -9 6969^M
> ...
> 
> But for kill_pid_of=inferior, we also have the gdbserver killed:
> ...
> Executing on target: pstree -a -p 6805    (timeout = 300)
> builtin_spawn -ignore SIGHUP pstree -a -p 6805^M
> gdbserver,6805^M
>    `-server-kill,6812^M
> Executing on target: kill -9 6805    (timeout = 300)
> builtin_spawn -ignore SIGHUP kill -9 6805^M
> ...
> 
> The proc prepare contains the pid extraction code:
> ...
>      if { $::kill_pid_of == "inferior" } {
>          # Get the pid of GDBServer.
>          set test "p server_pid"
>          set server_pid 0
>          gdb_test_multiple $test $test {
>              -re " = ($decimal)\r\n$gdb_prompt $" {
>                  set server_pid $expect_out(1,string)
>                  pass $test
>              }
>          }
>      } else {
>          set server_pid [exp_pid -i $::server_spawn_id]
>      }
> ...
> 
> The bit for $::kill_pid_of == "inferior" looks like the correct code to
> extract the gdbserver pid (it prints the parent PID of the inferior).
> 
> The bit for $::kill_pid_of == "server" does work for local target, but for
> remote target using say target board remote-gdbserver-on-localhost, we have:
> ...
> Executing on target: pstree -a -p 10354    (timeout = 300)
> builtin_spawn [open ...]^M
> ssh,10354 -l vries localhost/gdbserver --once localhost:2350 s
> XYZ0ZYX
> Executing on target: kill -9 10354    (timeout = 300)
> builtin_spawn [open ...]^M
> XYZ0ZYX
> ...
> In other words, we're not killing the gdbserver, but the ssh session (a
> problem which was already fixed once in commit f90183d7e31 ("Get GDBserver
> pid on remote target")).
> 
> Fix this by:
> - using the $::kill_pid_of == "inferior" bit for the gdbserver pid, and
> - using the inferior command for the the inferior pid.
> 
> This introduces the following 4 FAILs:
> ...
> FAIL: gdb.server/server-kill.exp: kill_pid_of=inferior: test_tstatus: tstatus
> FAIL: gdb.server/server-kill.exp: kill_pid_of=inferior: test_unwind_nosyms: bt
> FAIL: gdb.server/server-kill.exp: kill_pid_of=inferior: test_unwind_syms: bt
> FAIL: gdb.server/server-kill.exp: kill_pid_of=inferior: test_stepi: stepi
> ...
> 
> The first in more detail:
> ...
> (gdb) status-packet on
> tstatus^M
> No trace has been run on the target.^M
> Collected 0 trace frames.^M
> Trace buffer has 5242880 bytes of 5242880 bytes free (0% full).^M
> Trace will stop if GDB disconnects.^M
> Not looking at any trace frame.^M
> (gdb) FAIL: gdb.server/server-kill.exp: kill_pid_of=inferior: test_tstatus: tstatus
> ...
> 
> The test-case contains the comment:
> ...
>   # When KILL_PID_OF is set to 'inferior' then the pid we kill is that
>   # of the inferior running under gdbserver, when this process dies
>   # gdbserver itself will exit.
> ...
> but that doesn't seem to be happening.
> 
> I've added a sleep 60 after the kill to rule out any timing issues, and indeed
> after 60 seconds the gdbserver is still running.
> 
> I don't know gdbserver well enough to decide whether the test-case assumption
> is wrong and we need to fix the test-case, or there's a gdbserver problem
> which is known or for which we can file a PR.
> 
> Tested on x86_64-linux.
> 
> Any comments?
> 

Ping.

Thanks,
- Tom

> [gdb/testsuite] Fix inferior pid in gdb.server/server-kill.exp
> 
> ---
>   gdb/testsuite/gdb.server/server-kill.exp | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.server/server-kill.exp b/gdb/testsuite/gdb.server/server-kill.exp
> index 93daf482907..05f4f21bc0c 100644
> --- a/gdb/testsuite/gdb.server/server-kill.exp
> +++ b/gdb/testsuite/gdb.server/server-kill.exp
> @@ -75,10 +75,10 @@ proc prepare {} {
>       gdb_breakpoint ${srcfile}:[gdb_get_line_number "i = 0;"]
>       gdb_continue_to_breakpoint "after server_pid assignment"
>   
> -    if { $::kill_pid_of == "inferior" } {
> +    set server_pid 0
> +    if { $::kill_pid_of == "server" } {
>   	# Get the pid of GDBServer.
>   	set test "p server_pid"
> -	set server_pid 0
>   	gdb_test_multiple $test $test {
>   	    -re " = ($decimal)\r\n$gdb_prompt $" {
>   		set server_pid $expect_out(1,string)
> @@ -86,7 +86,13 @@ proc prepare {} {
>   	    }
>   	}
>       } else {
> -	set server_pid [exp_pid -i $::server_spawn_id]
> +	set test "inferior"
> +	gdb_test_multiple $test $test {
> +	    -re -wrap "Current inferior is 1 \\\[process ($decimal)\\\].*" {
> +		set server_pid $expect_out(1,string)
> +		pass $test
> +	    }
> +	}
>       }
>   
>       if {$server_pid == 0} {