Re: [PATCH v9] testpmd: cleanup cleanly from signal

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 1/25/2023 6:32 PM, Stephen Hemminger wrote:
> Do a clean shutdown of testpmd when a signal is received; instead of
> having testpmd kill itself.  This fixes the problem where a signal could
> be received in the middle of a PMD and then the signal handler would
> call PMD's close routine leading to locking problems.
> 
> An added benefit is it gets rid of some Windows specific code.
> 
> Fixes: d9a191a00e81 ("app/testpmd: fix quitting in container")
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Patch looks good to me, but './devtools/test-null.sh' hangs with change.

It is possible the fix by updating './devtools/test-null.sh', but my
concern is if this behavior change hit more consumers other than this
internal tool, and I am for keeping previous behavior.

'./devtools/test-null.sh' sends 'stop' command to testpmd but that seems
not really what makes testpmd quit, because following change still works
with original testpmd code:
 -(sleep 1 && echo stop) |
 +(sleep 1 && echo help) |
Somehow testpmd gets Ctrl-D or equivalent with above command.

And it seems because of 'cmdline_interact()' and 'cmdline_poll()'
difference behavior changes with above command.

It is possible to add something like  'cmdline_interact_one()' (non loop
version of 'cmdline_interact()'), but not really sure that is correct
way to fix the issue.


> ---
> v9 - also handle the interactive case.
>      use cmdine_poll() rather than signals and atexit
> 
>  app/test-pmd/cmdline.c | 28 +++++----------
>  app/test-pmd/testpmd.c | 77 ++++++++++++++++++++----------------------
>  app/test-pmd/testpmd.h |  1 +
>  3 files changed, 46 insertions(+), 60 deletions(-)
> 
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c
> index b32dc8bfd445..fbe9ad694dee 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -65,7 +65,6 @@
>  #include "cmdline_tm.h"
>  #include "bpf_cmd.h"
>  
> -static struct cmdline *testpmd_cl;
>  static cmdline_parse_ctx_t *main_ctx;
>  static TAILQ_HEAD(, testpmd_driver_commands) driver_commands_head =
>  	TAILQ_HEAD_INITIALIZER(driver_commands_head);
> @@ -12921,28 +12920,19 @@ cmdline_read_from_file(const char *filename)
>  void
>  prompt(void)
>  {
> -	int ret;
> +	struct cmdline *cl;
>  
> -	testpmd_cl = cmdline_stdin_new(main_ctx, "testpmd> ");
> -	if (testpmd_cl == NULL)
> +	cl = cmdline_stdin_new(main_ctx, "testpmd> ");
> +	if (cl == NULL)
>  		return;
>  
> -	ret = atexit(prompt_exit);
> -	if (ret != 0)
> -		fprintf(stderr, "Cannot set exit function for cmdline\n");
> -
> -	cmdline_interact(testpmd_cl);
> -	if (ret != 0)
> -		cmdline_stdin_exit(testpmd_cl);
> -}
> -
> -void
> -prompt_exit(void)
> -{
> -	if (testpmd_cl != NULL) {
> -		cmdline_quit(testpmd_cl);
> -		cmdline_stdin_exit(testpmd_cl);
> +	while (f_quit == 0 && cl_quit == 0) {
> +		if (cmdline_poll(cl) < 0)
> +			break;
>  	}
> +
> +	cmdline_quit(cl);
> +	cmdline_stdin_exit(cl);
>  }
>  
>  void
> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
> index 134d79a55547..d01b6105b7de 100644
> --- a/app/test-pmd/testpmd.c
> +++ b/app/test-pmd/testpmd.c
> @@ -11,6 +11,7 @@
>  #include <fcntl.h>
>  #ifndef RTE_EXEC_ENV_WINDOWS
>  #include <sys/mman.h>
> +#include <sys/select.h>
>  #endif
>  #include <sys/types.h>
>  #include <errno.h>
> @@ -231,7 +232,7 @@ unsigned int xstats_display_num; /**< Size of extended statistics to show */
>   * In container, it cannot terminate the process which running with 'stats-period'
>   * option. Set flag to exit stats period loop after received SIGINT/SIGTERM.
>   */
> -static volatile uint8_t f_quit;
> +volatile uint8_t f_quit;
>  uint8_t cl_quit; /* Quit testpmd from cmdline. */
>  
>  /*
> @@ -4315,13 +4316,6 @@ init_port(void)
>  	memset(txring_numa, NUMA_NO_CONFIG, RTE_MAX_ETHPORTS);
>  }
>  
> -static void
> -force_quit(void)
> -{
> -	pmd_test_exit();
> -	prompt_exit();
> -}
> -
>  static void
>  print_stats(void)
>  {
> @@ -4340,28 +4334,9 @@ print_stats(void)
>  }
>  
>  static void
> -signal_handler(int signum)
> +signal_handler(int signum __rte_unused)
>  {
> -	if (signum == SIGINT || signum == SIGTERM) {
> -		fprintf(stderr, "\nSignal %d received, preparing to exit...\n",
> -			signum);
> -#ifdef RTE_LIB_PDUMP
> -		/* uninitialize packet capture framework */
> -		rte_pdump_uninit();
> -#endif
> -#ifdef RTE_LIB_LATENCYSTATS
> -		if (latencystats_enabled != 0)
> -			rte_latencystats_uninit();
> -#endif
> -		force_quit();
> -		/* Set flag to indicate the force termination. */
> -		f_quit = 1;
> -		/* exit with the expected status */
> -#ifndef RTE_EXEC_ENV_WINDOWS
> -		signal(signum, SIG_DFL);
> -		kill(getpid(), signum);
> -#endif
> -	}
> +	f_quit = 1;
>  }
>  
>  int
> @@ -4536,15 +4511,9 @@ main(int argc, char** argv)
>  			start_packet_forwarding(0);
>  		}
>  		prompt();
> -		pmd_test_exit();
>  	} else
>  #endif
>  	{
> -		char c;
> -		int rc;
> -
> -		f_quit = 0;
> -
>  		printf("No commandline core given, start packet forwarding\n");
>  		start_packet_forwarding(tx_first);
>  		if (stats_period != 0) {
> @@ -4567,15 +4536,41 @@ main(int argc, char** argv)
>  				prev_time = cur_time;
>  				rte_delay_us_sleep(US_PER_S);
>  			}
> -		}
> +		} else {
> +			char c;
> +			fd_set fds;
> +
> +			printf("Press enter to exit\n");
>  
> -		printf("Press enter to exit\n");
> -		rc = read(0, &c, 1);
> -		pmd_test_exit();
> -		if (rc < 0)
> -			return 1;
> +			FD_ZERO(&fds);
> +			FD_SET(0, &fds);
> +
> +			/* wait for signal or enter */
> +			ret = select(1, &fds, NULL, NULL, NULL);
> +			if (ret < 0 && errno != EINTR)
> +				rte_exit(EXIT_FAILURE,
> +					 "Select failed: %s\n",
> +					 strerror(errno));
> +
> +			/* if got enter then consume it */
> +			if (ret == 1 && read(0, &c, 1) < 0)
> +				rte_exit(EXIT_FAILURE,
> +					 "Read failed: %s\n",
> +					 strerror(errno));
> +		}
>  	}
>  
> +	pmd_test_exit();
> +
> +#ifdef RTE_LIB_PDUMP
> +	/* uninitialize packet capture framework */
> +	rte_pdump_uninit();
> +#endif
> +#ifdef RTE_LIB_LATENCYSTATS
> +	if (latencystats_enabled != 0)
> +		rte_latencystats_uninit();
> +#endif
> +
>  	ret = rte_eal_cleanup();
>  	if (ret != 0)
>  		rte_exit(EXIT_FAILURE,
> diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h
> index 7d24d25970d2..022210a7a964 100644
> --- a/app/test-pmd/testpmd.h
> +++ b/app/test-pmd/testpmd.h
> @@ -34,6 +34,7 @@
>  #define RTE_PORT_HANDLING       (uint16_t)3
>  
>  extern uint8_t cl_quit;
> +extern volatile uint8_t f_quit;
>  
>  /*
>   * It is used to allocate the memory for hash key.