[DTrace-devel] [PATCH 18/38] Add a provider-specific probe_add_clause for underlying probes

[Kris Van Hees]

See comments in 16/38

On Thu, Jun 27, 2024 at 01:34:35AM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  libdtrace/dt_prov_uprobe.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/libdtrace/dt_prov_uprobe.c b/libdtrace/dt_prov_uprobe.c
> index c77063a8..5dbd75e3 100644
> --- a/libdtrace/dt_prov_uprobe.c
> +++ b/libdtrace/dt_prov_uprobe.c
> @@ -129,6 +129,38 @@ static void probe_destroy(dtrace_hdl_t *dtp, void *datap)
>  	free_probe_list(dtp, datap);
>  }
>  
> +/*
> + * Add clause to probe.
> + */
> +static int probe_add_clause(dtrace_hdl_t *dtp, dt_probe_t *prp, dt_ident_t *idp)
> +{
> +	const list_probe_t	*pup;
> +
> +	for (pup = prp->prv_data; pup != NULL; pup = dt_list_next(pup)) {
> +		dt_probe_t		*uprp = pup->probe;
> +		dt_probe_clause_t	*prev, *pcp;
> +
> +		/*
> +		 * Check if the clause is already there.  Since the clauses
> +		 * are added "in order," we only need to check the previous
> +		 * entry.
> +		 */
> +		prev = dt_list_prev(&uprp->clauses);
> +		if (prev && strcmp(prev->clause->di_name, idp->di_name) == 0)
> +			continue;
> +
> +		/*
> +		 * Add the clause.
> +		 */
> +		pcp = dt_zalloc(dtp, sizeof(dt_probe_clause_t));
> +		if (pcp == NULL)
> +			return -1;
> +		pcp->clause = idp;
> +		dt_list_append(&uprp->clauses, pcp);
> +	}
> +
> +	return 0;
> +}
>  
>  /*
>   * Look up or create an underlying (real) probe, corresponding directly to a
> @@ -811,6 +843,7 @@ dt_provimpl_t	dt_pid = {
>  	.prog_type	= BPF_PROG_TYPE_UNSPEC,
>  	.provide_probe	= &provide_pid_probe,
>  	.enable		= &enable_pid,
> +	.probe_add_clause = &probe_add_clause,
>  	.probe_destroy	= &probe_destroy,
>  };
>  
> @@ -822,5 +855,6 @@ dt_provimpl_t	dt_usdt = {
>  	.prog_type	= BPF_PROG_TYPE_UNSPEC,
>  	.provide_probe	= &provide_usdt_probe,
>  	.enable		= &enable_usdt,
> +	.probe_add_clause = &probe_add_clause,
>  	.probe_destroy	= &probe_destroy,
>  };
> -- 
> 2.18.4
>