[DTrace-devel] [PATCH 02/14] Clean up prp/uprp variable names

[eugene.loh at oracle.com]

From: Eugene Loh <eugene.loh at oracle.com>

Should prp be oprp?  Or should we use opr and upr?

Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
 libdtrace/dt_prov_uprobe.c | 55 +++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/libdtrace/dt_prov_uprobe.c b/libdtrace/dt_prov_uprobe.c
index afc1f628..cace406d 100644
--- a/libdtrace/dt_prov_uprobe.c
+++ b/libdtrace/dt_prov_uprobe.c
@@ -6,6 +6,31 @@
  *
  * The uprobe-based provider for DTrace (implementing pid and USDT providers).
  */
+/*
+ * This file uses both overlying probes (specified by the user) as well as
+ * underlying probes (the uprobes recognized by the kernel).  To minimize
+ * confusion, this file should use consistent variable names:
+ *
+ *     dt_probe_t	*prp;   //  overlying probe
+ *     dt_probe_t	*uprp;  // underlying probe
+ *
+ *             Either one might be returned by dt_probe_lookup() or
+ *             dt_probe_insert() or added to dt_enablings[] or dt_probes[].
+ *             Further, uprp might be returned by create_underlying().
+ *
+ *     dt_uprobe_t	*upp;   // uprobe associated with an underlying probe
+ *
+ *     list_probe_t	*pop;   //  overlying probe list
+ *     list_probe_t	*pup;   // underlying probe list
+ *
+ * The provider-specific prv_data has these meanings:
+ *
+ *     prp->prv_data            // dt_list_t of associated underlying probes
+ *
+ *     uprp->prv_data           // upp (the associated uprobe)
+ *
+ * Finally, note that upp->probes is a dt_list_t of overlying probes.
+ */
 #include <sys/types.h>
 #include <assert.h>
 #include <errno.h>
@@ -118,7 +143,7 @@ static dt_probe_t *create_underlying(dtrace_hdl_t *dtp,
 	char			mod[DTRACE_MODNAMELEN];
 	char			prb[DTRACE_NAMELEN];
 	dtrace_probedesc_t	pd;
-	dt_probe_t		*prp;
+	dt_probe_t		*uprp;
 	dt_uprobe_t		*upp;
 	int			is_enabled = 0;
 
@@ -160,8 +185,8 @@ static dt_probe_t *create_underlying(dtrace_hdl_t *dtp,
 	pd.fun = psp->pps_fun;
 	pd.prb = prb;
 
-	prp = dt_probe_lookup(dtp, &pd);
-	if (prp == NULL) {
+	uprp = dt_probe_lookup(dtp, &pd);
+	if (uprp == NULL) {
 		dt_provider_t	*pvp;
 
 		/* Get the provider for underlying probes. */
@@ -182,12 +207,12 @@ static dt_probe_t *create_underlying(dtrace_hdl_t *dtp,
 		if (upp->tp == NULL)
 			goto fail;
 
-		prp = dt_probe_insert(dtp, pvp, pd.prv, pd.mod, pd.fun, pd.prb,
+		uprp = dt_probe_insert(dtp, pvp, pd.prv, pd.mod, pd.fun, pd.prb,
 				      upp);
-		if (prp == NULL)
+		if (uprp == NULL)
 			goto fail;
 	} else
-		upp = prp->prv_data;
+		upp = uprp->prv_data;
 
 	switch (psp->pps_type) {
 	case DTPPT_RETURN:
@@ -202,7 +227,7 @@ static dt_probe_t *create_underlying(dtrace_hdl_t *dtp,
 	     */
 	}
 
-	return prp;
+	return uprp;
 
 fail:
 	probe_destroy(dtp, upp);
@@ -394,8 +419,8 @@ static void enable_usdt(dtrace_hdl_t *dtp, dt_probe_t *prp)
 static int trampoline(dt_pcb_t *pcb, uint_t exitlbl)
 {
 	dt_irlist_t		*dlp = &pcb->pcb_ir;
-	const dt_probe_t	*prp = pcb->pcb_probe;
-	const dt_uprobe_t	*upp = prp->prv_data;
+	const dt_probe_t	*uprp = pcb->pcb_probe;
+	const dt_uprobe_t	*upp = uprp->prv_data;
 	const list_probe_t	*pop;
 	uint_t			lbl_exit = pcb->pcb_exitlbl;
 
@@ -508,8 +533,8 @@ copyout_val(dt_pcb_t *pcb, uint_t lbl, uint32_t val, int arg)
 static int trampoline_is_enabled(dt_pcb_t *pcb, uint_t exitlbl)
 {
 	dt_irlist_t		*dlp = &pcb->pcb_ir;
-	const dt_probe_t	*prp = pcb->pcb_probe;
-	const dt_uprobe_t	*upp = prp->prv_data;
+	const dt_probe_t	*uprp = pcb->pcb_probe;
+	const dt_uprobe_t	*upp = uprp->prv_data;
 	const list_probe_t	*pop;
 	uint_t			lbl_assign = dt_irlist_label(dlp);
 	uint_t			lbl_exit = pcb->pcb_exitlbl;
@@ -636,9 +661,9 @@ out:
 	return name;
 }
 
-static int attach(dtrace_hdl_t *dtp, const dt_probe_t *prp, int bpf_fd)
+static int attach(dtrace_hdl_t *dtp, const dt_probe_t *uprp, int bpf_fd)
 {
-	dt_uprobe_t	*upp = prp->prv_data;
+	dt_uprobe_t	*upp = uprp->prv_data;
 	tp_probe_t	*tpp = upp->tp;
 	FILE		*f;
 	char		*fn;
@@ -733,9 +758,9 @@ out:
  * probes that didn't get created.  If the removal fails for some reason we are
  * out of luck - fortunately it is not harmful to the system as a whole.
  */
-static void detach(dtrace_hdl_t *dtp, const dt_probe_t *prp)
+static void detach(dtrace_hdl_t *dtp, const dt_probe_t *uprp)
 {
-	dt_uprobe_t	*upp = prp->prv_data;
+	dt_uprobe_t	*upp = uprp->prv_data;
 	tp_probe_t	*tpp = upp->tp;
 
 	if (!dt_tp_has_info(tpp))
-- 
2.18.4