[DTrace-devel] [PATCH 3/5] usdt: provide probes properly when >1 is specified

[Kris Van Hees]

On Mon, Apr 24, 2023 at 08:08:14PM +0100, Nick Alcock via DTrace-devel wrote:
> dt_pid_create_usdt_probes is called by dt_pid_create_probes, which
> despite its name is usually called by the compiler to set the context
> for one probe at a time, not all at once. So dt_pid_create_usdt_probes
> is usually (currently: always) called in a mode in which it scans all
> the probes and then creates only those it has been asked to create.
> So we really do need to not skip invocations after the first.
> 
> This will obviously not work well for wildcard probe handling, but for
> now the inefficient approach of just repeated rescanning should work
> well enough.
> 
> Signed-off-by: Nick Alcock <nick.alcock at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

> ---
>  libdtrace/dt_pid.c                | 7 +++----
>  libdtrace/dt_proc.h               | 1 -
>  test/unittest/usdt/tst.allargs.sh | 2 --
>  3 files changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/libdtrace/dt_pid.c b/libdtrace/dt_pid.c
> index 06bd7a4dd24aa..4be230ace1bf8 100644
> --- a/libdtrace/dt_pid.c
> +++ b/libdtrace/dt_pid.c
> @@ -742,6 +742,8 @@ dt_pid_create_usdt_probes(dtrace_hdl_t *dtp, dt_proc_t *dpr,
>  		 * probe: we'll complain later if we use it for anything.
>  		 */
>  
> +		dt_dprintf("providing %s:%s:%s:%s\n", pdp->prv, pdp->mod,
> +			   pdp->fun, pdp->prb);
>  		if (pvp->impl->provide_probe(dtp, &psp) < 0 && pdp) {
>  			dt_pid_error(dtp, pcb, dpr, D_PROC_USDT,
>  				     "failed to instantiate %sprobe %s for pid %d: %s",
> @@ -921,10 +923,7 @@ dt_pid_create_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp, dt_pcb_t *pcb)
>  		dpr = dt_proc_lookup(dtp, pid);
>  		assert(dpr != NULL);
>  
> -		if (!dpr->dpr_usdt) {
> -			err = dt_pid_create_usdt_probes(dtp, dpr, pdp, pcb);
> -			dpr->dpr_usdt = B_TRUE;
> -		}
> +		err = dt_pid_create_usdt_probes(dtp, dpr, pdp, pcb);
>  
>  		dt_proc_release_unlock(dtp, pid);
>  	}
> diff --git a/libdtrace/dt_proc.h b/libdtrace/dt_proc.h
> index 2b4f4d0f03cf0..0ec1caf08fbfa 100644
> --- a/libdtrace/dt_proc.h
> +++ b/libdtrace/dt_proc.h
> @@ -39,7 +39,6 @@ typedef struct dt_proc {
>  	uint_t dpr_refs;		/* reference count */
>  	uint8_t dpr_stop;		/* stop mask: see flag bits below */
>  	uint8_t dpr_done;		/* done flag: ctl thread has exited */
> -	uint8_t dpr_usdt;		/* usdt flag: usdt initialized */
>  	uint8_t dpr_created;            /* proc flag: true if we created this
>  					   process, false if we grabbed it */
>  	uint8_t dpr_monitoring;		/* true if we should background-monitor
> diff --git a/test/unittest/usdt/tst.allargs.sh b/test/unittest/usdt/tst.allargs.sh
> index f0484793206f7..20f9de900b5ad 100755
> --- a/test/unittest/usdt/tst.allargs.sh
> +++ b/test/unittest/usdt/tst.allargs.sh
> @@ -4,8 +4,6 @@
>  # Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
>  # Licensed under the Universal Permissive License v 1.0 as shown at
>  # http://oss.oracle.com/licenses/upl.
> -#
> -# @@xfail: dtv2
>  
>  # This test covers all USDT probes fired by the DTRACE_PROBEn macros.
>  # Arguments values are checked only for first 10 arguments because
> -- 
> 2.39.1.268.g9de2f9a303
> 
> 
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