[DTrace-devel] [PATCH 07/17] providers: allow providers with no trampoline

[Nick Alcock]

These can be enabled just like any other, but generate no code.

Meant for use by things like the pid provider which have two
probes associated with each system-side probe, one of which
gets fired and generates code for the others in its trampoline
method.
---
 libdtrace/dt_bpf.c | 7 +++++++
 libdtrace/dt_cg.c  | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
index 5ff348ca6370..42b4b80c0a68 100644
--- a/libdtrace/dt_bpf.c
+++ b/libdtrace/dt_bpf.c
@@ -719,6 +719,13 @@ dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
 		if (prp == dtp->dt_error)
 			continue;
 
+		/*
+		 * Enabled probes with no trampoline act like they exist but
+		 * no code is generated for them.
+		 */
+		if (prp->prov->impl->trampoline == NULL)
+			continue;
+
 		dp = dt_program_construct(dtp, prp, cflags, NULL);
 		if (dp == NULL)
 			return -1;
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index ebd4190698f7..9f9d0fb03028 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -6846,7 +6846,8 @@ dt_cg(dt_pcb_t *pcb, dt_node_t *dnp)
 	} else if (dnp->dn_kind == DT_NODE_TRAMPOLINE) {
 		assert(pcb->pcb_probe != NULL);
 
-		pcb->pcb_probe->prov->impl->trampoline(pcb);
+		if (pcb->pcb_probe->prov->impl->trampoline != NULL)
+			pcb->pcb_probe->prov->impl->trampoline(pcb);
 	} else
 		dt_cg_node(dnp, &pcb->pcb_ir, pcb->pcb_regs);
 
-- 
2.37.1.265.g363c192786.dirty