Re: [PATCH] gdb/amd-dbgapi-target: suppress a repeated stop request

[Lancelot SIX <Lancelot.Six@amd.com>]

Hi,

On 20/05/2026 09:58, Tankut Baris Aktemur wrote:
> Sending a second stop request to an AMD GPU thread before fetching the
> event caused by the first request leads to an error:
> 
>    wave_stop for wave_1 failed (The wave has an outstanding stop request)
> 
> Prevent sending a new stop request if there already is an outstanding
> one.  The fix is in amd_dbgapi_target::stop.
> 
> A regression test is included.  The test uses non-stop mode and
> executes the "interrupt" command twice, because in non-stop mode this
> command uses the 'stop' target op, where the fix is applied.
> 
> To be able to execute two interrupt commands repeatedly, we define a
> user command.
> ---
>   gdb/amd-dbgapi-target.c                    |  8 ++-
>   gdb/testsuite/gdb.rocm/interrupt-twice.cpp | 43 ++++++++++++
>   gdb/testsuite/gdb.rocm/interrupt-twice.exp | 82 ++++++++++++++++++++++
>   3 files changed, 130 insertions(+), 3 deletions(-)
>   create mode 100644 gdb/testsuite/gdb.rocm/interrupt-twice.cpp
>   create mode 100644 gdb/testsuite/gdb.rocm/interrupt-twice.exp
> 
> diff --git a/gdb/amd-dbgapi-target.c b/gdb/amd-dbgapi-target.c
> index 421ec8599ed..d44f03d0b80 100644
> --- a/gdb/amd-dbgapi-target.c
> +++ b/gdb/amd-dbgapi-target.c
> @@ -1090,14 +1090,16 @@ amd_dbgapi_target::stop (ptid_t ptid)
>   				    sizeof (state), &state);
>         if (status == AMD_DBGAPI_STATUS_SUCCESS)
>   	{
> -	  /* If the wave is already known to be stopped then do nothing.  */
> -	  if (state == AMD_DBGAPI_WAVE_STATE_STOP)
> +	  wave_info &wi = get_thread_wave_info (thread);
> +
> +	  /* If the wave is already known to be stopped or there is an
> +	     outstanding stop request, then do nothing.  */
> +	  if (state == AMD_DBGAPI_WAVE_STATE_STOP || wi.stopping)
>   	    return;
>   
>   	  status = amd_dbgapi_wave_stop (wave_id);
>   	  if (status == AMD_DBGAPI_STATUS_SUCCESS)
>   	    {
> -	      wave_info &wi = get_thread_wave_info (thread);
>   	      wi.stopping = true;
>   	      return;
>   	    }
> diff --git a/gdb/testsuite/gdb.rocm/interrupt-twice.cpp b/gdb/testsuite/gdb.rocm/interrupt-twice.cpp
> new file mode 100644
> index 00000000000..fc8d2cca697
> --- /dev/null
> +++ b/gdb/testsuite/gdb.rocm/interrupt-twice.cpp
> @@ -0,0 +1,43 @@
> +/* Copyright 2026 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include <hip/hip_runtime.h>
> +#include "gdb_watchdog.h"
> +
> +__device__ void
> +loop ()
> +{
> +  while (true)
> +    __builtin_amdgcn_s_sleep (8);
> +}
> +
> +__global__ void
> +kern ()
> +{
> +  loop ();
> +}
> +
> +int
> +main ()
> +{
> +  /* Make sure that if anything goes wrong, the program eventually
> +     gets killed.  */
> +  gdb_watchdog (30);
> +
> +  kern<<<1, 1>>> ();
> +  return hipDeviceSynchronize () != hipSuccess;
> +}
> diff --git a/gdb/testsuite/gdb.rocm/interrupt-twice.exp b/gdb/testsuite/gdb.rocm/interrupt-twice.exp
> new file mode 100644
> index 00000000000..681efab0af3
> --- /dev/null
> +++ b/gdb/testsuite/gdb.rocm/interrupt-twice.exp
> @@ -0,0 +1,82 @@
> +# Copyright 2026 Free Software Foundation, Inc.
> +
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +# Test that sending repeated stop requests to a running GPU thread
> +# does not cause a failure.  This is done in non-stop mode because
> +# "interrupt" command in this mode uses the 'stop' target op.
> +
> +load_lib rocm.exp
> +
> +require allow_hipcc_tests
> +
> +standard_testfile .cpp
> +
> +if {[build_executable "failed to prepare" $testfile $srcfile {debug hip}]} {
> +    return
> +}
> +
> +with_rocm_gpu_lock {
> +    save_vars { ::GDBFLAGS } {
> +	append ::GDBFLAGS " -ex \"set non-stop on\""
> +	clean_restart $::testfile
> +    }
> +
> +    gdb_breakpoint "loop" {allow-pending} {temporary}
> +    gdb_run_cmd
> +
> +    set gpu_thread "undefined"
> +
> +    gdb_test_multiple "" "hit breakpoint" {
> +	-re -wrap "Thread ($decimal) \[^\r\n\]*hit Temporary breakpoint.*" {
> +	    set gpu_thread $expect_out(1,string)
> +	    pass $gdb_test_name
> +	}
> +    }
> +
> +    gdb_test "thread $gpu_thread" "Switching to.*" "switch to gpu thread"
> +
> +    # Resume the thread in the background.  It will loop.  Then we
> +    # interrupt twice.  To be able to run the "interrupt" command back
> +    # to back, we define a user command.
> +    gdb_test "continue &" "Continuing." "continue async"
> +
> +    gdb_test_multiple "define inttwice" "" {
> +	-re "End with .*>$"  {
> +	    pass $gdb_test_name
> +	}
> +    }
> +
> +    gdb_test [multi_line_input \
> +		  {interrupt} \
> +		  {interrupt} \
> +		  {end}] \
> +	"" \
> +	"enter commands"

Having 2 tests here seems odd. There should be just one PASS/FAIL for 
the entire command.

There are 2 approaches to do this.

First, gdb_test has all the machinery in place to do the "question - 
response" interaction:

     gdb_test \
       "define inttwice" \
       "" \
       "define inttwice" \
       "Type commands for definition of \"inttwice\"\.\r\nEnd with a 
line saying just \"end\"\.\r\n>" \
       [multi_line_input "interrupt" "interrupt" "end"]

The second approach is to use gdb_test_multiple all the way, and use 
send_gdb to reply to the question

     gdb_test_multiple "define inttwice" "" {
	-re "Type commands for definition of \"inttwice\"\.\r\nEnd with a line 
saying just \"end\"\.\r\n>$" {
		send_gdb [multi_line_input "interrupt" "interrupt" "end" ""]
		exp_continue
	}
	-re "$::gdb_prompt $" {
		pass $gdb_test_name
	}
     }

The rest looks reasonable to me.

Best,
Lancelot.

> +
> +    # For logging purposes.
> +    gdb_test "show user inttwice"
> +
> +    gdb_test_multiple "inttwice" "interrupt twice" {
> +	-re "wave_stop \[^\r\n\]+ failed \[^\r\n\]+ outstanding stop request\\)\r\n" {
> +	    fail $gdb_test_name
> +	}
> +	-re "Thread $gpu_thread \[^\r\n\]*stopped" {
> +	    pass $gdb_test_name
> +	}
> +	-re "$gdb_prompt" {
> +	    exp_continue
> +	}
> +    }
> +}