[DTrace-devel] [PATCH 07/38] Clean up prp/pprp/uprp variable names
eugene.loh at oracle.com
eugene.loh at oracle.com
Thu Jun 27 05:34:24 UTC 2024
From: Eugene Loh <eugene.loh at oracle.com>
Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
libdtrace/dt_prov_uprobe.c | 83 +++++++++++++++++++++++++-------------
1 file changed, 55 insertions(+), 28 deletions(-)
diff --git a/libdtrace/dt_prov_uprobe.c b/libdtrace/dt_prov_uprobe.c
index afc1f628..c77063a8 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);
@@ -259,7 +284,7 @@ static int provide_probe(dtrace_hdl_t *dtp, const pid_probespec_t *psp,
}
/*
- * Underlying and overlying probe list entries.
+ * Overlying and underlying probe list entries.
*/
pop = dt_zalloc(dtp, sizeof(list_probe_t));
if (pop == NULL)
@@ -271,7 +296,10 @@ static int provide_probe(dtrace_hdl_t *dtp, const pid_probespec_t *psp,
return -1;
}
- /* Add the pid probe, if we need to. */
+ /*
+ * Add the underlying probe to the list of probes for the overlying probe,
+ * adding the overlying probe if we need to.
+ */
pup->probe = uprp;
if (prp == NULL)
@@ -286,11 +314,10 @@ static int provide_probe(dtrace_hdl_t *dtp, const pid_probespec_t *psp,
return -1;
}
- pop->probe = prp;
-
/*
- * Add the pid probe to the list of probes for the underlying probe.
+ * Add the overlying probe to the list of probes for the underlying probe.
*/
+ pop->probe = prp;
dt_list_append(&upp->probes, pop);
return 0;
@@ -394,8 +421,8 @@ 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;
@@ -441,15 +468,15 @@ static int trampoline(dt_pcb_t *pcb, uint_t exitlbl)
*/
for (pop = dt_list_next(&upp->probes); pop != NULL;
pop = dt_list_next(pop)) {
- const dt_probe_t *pprp = pop->probe;
+ const dt_probe_t *prp = pop->probe;
uint_t lbl_next = dt_irlist_label(dlp);
pid_t pid;
dt_ident_t *idp;
- pid = dt_pid_get_pid(pprp->desc, pcb->pcb_hdl, pcb, NULL);
+ pid = dt_pid_get_pid(prp->desc, pcb->pcb_hdl, pcb, NULL);
assert(pid != -1);
- idp = dt_dlib_add_probe_var(pcb->pcb_hdl, pprp);
+ idp = dt_dlib_add_probe_var(pcb->pcb_hdl, prp);
assert(idp != NULL);
/*
@@ -457,8 +484,8 @@ static int trampoline(dt_pcb_t *pcb, uint_t exitlbl)
* process, and emit a sequence of clauses for it when it does.
*/
emit(dlp, BPF_BRANCH_IMM(BPF_JNE, BPF_REG_0, pid, lbl_next));
- emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_7, DMST_PRID, pprp->desc->id), idp);
- dt_cg_tramp_call_clauses(pcb, pprp, DT_ACTIVITY_ACTIVE);
+ emite(dlp, BPF_STORE_IMM(BPF_W, BPF_REG_7, DMST_PRID, prp->desc->id), idp);
+ dt_cg_tramp_call_clauses(pcb, prp, DT_ACTIVITY_ACTIVE);
emit(dlp, BPF_JUMP(lbl_exit));
emitl(dlp, lbl_next,
BPF_NOP());
@@ -508,8 +535,8 @@ 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;
@@ -561,14 +588,14 @@ static int trampoline_is_enabled(dt_pcb_t *pcb, uint_t exitlbl)
*/
for (pop = dt_list_next(&upp->probes); pop != NULL;
pop = dt_list_next(pop)) {
- const dt_probe_t *pprp = pop->probe;
+ const dt_probe_t *prp = pop->probe;
pid_t pid;
dt_ident_t *idp;
- pid = dt_pid_get_pid(pprp->desc, pcb->pcb_hdl, pcb, NULL);
+ pid = dt_pid_get_pid(prp->desc, pcb->pcb_hdl, pcb, NULL);
assert(pid != -1);
- idp = dt_dlib_add_probe_var(pcb->pcb_hdl, pprp);
+ idp = dt_dlib_add_probe_var(pcb->pcb_hdl, prp);
assert(idp != NULL);
/*
@@ -636,9 +663,9 @@ 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 +760,9 @@ 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
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