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sdt: Tear down probes in kernel modules during kldunload

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Previously only providers in kernel modules were removed leaving
dangling pointers to tracepoints, etc. in unloaded kernel modules.

PR:		281825
Reported by:	Sony Arpita Das <sonyarpitad@chelsio.com>
Reviewed by:	markj
Fixes:		ddf0ed09bd sdt: Implement SDT probes using hot-patching
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D46890
This commit is contained in:
John Baldwin 2024-10-16 13:50:37 -04:00
parent 0aa4a9fc85
commit 47f49dd4bb
1 changed files with 102 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

111
sys/cddl/dev/sdt/sdt.c
View File

@ -429,18 +429,15 @@ sdt_kld_load(void *arg __unused, struct linker_file *lf)
sdt_kld_load_probes(lf);
}
static void
sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
static bool
sdt_kld_unload_providers(struct linker_file *lf)
{
struct sdt_provider *prov, **curr, **begin, **end, *tmp;
if (*error != 0)
/* We already have an error, so don't do anything. */
return;
else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
NULL))
/* No DTrace providers are declared in this file. */
return;
return (true);
/*
* Go through all the providers declared in this linker file and
@ -453,8 +450,7 @@ sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
if (prov->sdt_refs == 1) {
if (dtrace_unregister(prov->id) != 0) {
*error = 1;
return;
return (false);
}
TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
free(prov->name, M_SDT);
@ -464,6 +460,103 @@ sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
break;
}
}
return (true);
}
static bool
sdt_kld_unload_probes(struct linker_file *lf)
{
struct sdt_probe **p_begin, **p_end;
struct sdt_argtype **a_begin, **a_end;
struct sdt_tracepoint *tp_begin, *tp_end;
if (linker_file_lookup_set(lf, __XSTRING(_SDT_TRACEPOINT_SET),
&tp_begin, &tp_end, NULL) == 0) {
for (struct sdt_tracepoint *tp = tp_begin; tp < tp_end; tp++) {
struct sdt_tracepoint *tp2;
if (!sdt_tracepoint_valid(tp->patchpoint, tp->target))
continue;
/* Only remove the entry if it is in the list. */
tp2 = STAILQ_FIRST(&tp->probe->tracepoint_list);
if (tp2 == tp) {
STAILQ_REMOVE_HEAD(&tp->probe->tracepoint_list,
tracepoint_entry);
} else if (tp2 != NULL) {
struct sdt_tracepoint *tp3;
for (;;) {
tp3 = STAILQ_NEXT(tp2,
tracepoint_entry);
if (tp3 == NULL)
break;
if (tp3 == tp) {
STAILQ_REMOVE_AFTER(
&tp->probe->tracepoint_list,
tp2, tracepoint_entry);
break;
}
tp2 = tp3;
}
}
}
}
if (linker_file_lookup_set(lf, "sdt_argtypes_set", &a_begin, &a_end,
NULL) == 0) {
for (struct sdt_argtype **argtype = a_begin; argtype < a_end;
argtype++) {
struct sdt_argtype *argtype2;
/* Only remove the entry if it is in the list. */
TAILQ_FOREACH(argtype2,
&(*argtype)->probe->argtype_list, argtype_entry) {
if (argtype2 == *argtype) {
(*argtype)->probe->n_args--;
TAILQ_REMOVE(
&(*argtype)->probe->argtype_list,
*argtype, argtype_entry);
break;
}
}
}
}
if (linker_file_lookup_set(lf, "sdt_probes_set", &p_begin, &p_end,
NULL) == 0) {
for (struct sdt_probe **probe = p_begin; probe < p_end;
probe++) {
if ((*probe)->sdtp_lf == lf) {
if (!TAILQ_EMPTY(&(*probe)->argtype_list))
return (false);
if (!STAILQ_EMPTY(&(*probe)->tracepoint_list))
return (false);
/*
* Don't destroy the probe as there
* might be multiple instances of the
* same probe in different modules.
*/
}
}
}
return (true);
}
static void
sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
{
if (*error != 0)
/* We already have an error, so don't do anything. */
return;
if (!sdt_kld_unload_probes(lf))
*error = 1;
else if (!sdt_kld_unload_providers(lf))
*error = 1;
}
static int