Author: avg
Date: Mon Feb 17 12:48:19 2014
New Revision: 262041
URL: http://svnweb.freebsd.org/changeset/base/262041
Log:
MFC r257152: Do some cleanup of the SDT code
Modified:
stable/9/sys/cddl/dev/sdt/sdt.c
stable/9/sys/sys/sdt.h
Directory Properties:
stable/9/sys/ (props changed)
stable/9/sys/sys/ (props changed)
Modified: stable/9/sys/cddl/dev/sdt/sdt.c
==============================================================================
--- stable/9/sys/cddl/dev/sdt/sdt.c Mon Feb 17 12:48:05 2014
(r262040)
+++ stable/9/sys/cddl/dev/sdt/sdt.c Mon Feb 17 12:48:19 2014
(r262041)
@@ -24,6 +24,21 @@
*
*/
+/*
+ * This file contains a reimplementation of the statically-defined tracing
(SDT)
+ * framework for DTrace. Probes and SDT providers are defined using the macros
+ * in sys/sdt.h, which append all the needed structures to linker sets. When
+ * this module is loaded, it iterates over all of the loaded modules and
+ * registers probes and providers with the DTrace framework based on the
+ * contents of these linker sets.
+ *
+ * A list of SDT providers is maintained here since a provider may span
multiple
+ * modules. When a kernel module is unloaded, a provider defined in that module
+ * is unregistered only if no other modules refer to it. The DTrace framework
is
+ * responsible for destroying individual probes when a kernel module is
+ * unloaded; in particular, probes may not span multiple kernel modules.
+ */
+
#include "opt_kdtrace.h"
#include <sys/cdefs.h>
@@ -53,9 +68,8 @@ static void sdt_destroy(void *, dtrace_i
static void sdt_enable(void *, dtrace_id_t, void *);
static void sdt_disable(void *, dtrace_id_t, void *);
-static d_open_t sdt_open;
-static void sdt_load(void *);
-static int sdt_unload(void *);
+static void sdt_load(void);
+static int sdt_unload(void);
static void sdt_create_provider(struct sdt_provider *);
static void sdt_create_probe(struct sdt_probe *);
static void sdt_kld_load(void *, struct linker_file *);
@@ -63,12 +77,6 @@ static void sdt_kld_unload_try(void *, s
static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers");
-static struct cdevsw sdt_cdevsw = {
- .d_version = D_VERSION,
- .d_open = sdt_open,
- .d_name = "sdt",
-};
-
static dtrace_pattr_t sdt_attr = {
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
@@ -90,8 +98,6 @@ static dtrace_pops_t sdt_pops = {
sdt_destroy,
};
-static struct cdev *sdt_cdev;
-
static TAILQ_HEAD(, sdt_provider) sdt_prov_list;
eventhandler_tag sdt_kld_load_tag;
@@ -117,7 +123,6 @@ sdt_create_provider(struct sdt_provider
newprov = malloc(sizeof(*newprov), M_SDT, M_WAITOK | M_ZERO);
newprov->name = strdup(prov->name, M_SDT);
prov->sdt_refs = newprov->sdt_refs = 1;
- TAILQ_INIT(&newprov->probe_list);
TAILQ_INSERT_TAIL(&sdt_prov_list, newprov, prov_entry);
@@ -161,12 +166,14 @@ sdt_create_probe(struct sdt_probe *probe
if (dtrace_probe_lookup(prov->id, mod, func, name) != DTRACE_IDNONE)
return;
- TAILQ_INSERT_TAIL(&prov->probe_list, probe, probe_entry);
-
(void)dtrace_probe_create(prov->id, mod, func, name, 1, probe);
}
-/* Probes are created through the SDT module load/unload hook. */
+/*
+ * Probes are created through the SDT module load/unload hook, so this function
+ * has nothing to do. It only exists because the DTrace provider framework
+ * requires one of provide_probes and provide_module to be defined.
+ */
static void
sdt_provide_probes(void *arg, dtrace_probedesc_t *desc)
{
@@ -198,39 +205,39 @@ sdt_getargdesc(void *arg, dtrace_id_t id
struct sdt_argtype *argtype;
struct sdt_probe *probe = parg;
- if (desc->dtargd_ndx < probe->n_args) {
- TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
- if (desc->dtargd_ndx == argtype->ndx) {
- desc->dtargd_mapping = desc->dtargd_ndx;
- strlcpy(desc->dtargd_native, argtype->type,
- sizeof(desc->dtargd_native));
- if (argtype->xtype != NULL)
- strlcpy(desc->dtargd_xlate,
- argtype->xtype,
- sizeof(desc->dtargd_xlate));
- else
- desc->dtargd_xlate[0] = '\0';
+ if (desc->dtargd_ndx >= probe->n_args) {
+ desc->dtargd_ndx = DTRACE_ARGNONE;
+ return;
+ }
+
+ TAILQ_FOREACH(argtype, &probe->argtype_list, argtype_entry) {
+ if (desc->dtargd_ndx == argtype->ndx) {
+ desc->dtargd_mapping = desc->dtargd_ndx;
+ if (argtype->type == NULL) {
+ desc->dtargd_native[0] = '\0';
+ desc->dtargd_xlate[0] = '\0';
+ continue;
}
+ strlcpy(desc->dtargd_native, argtype->type,
+ sizeof(desc->dtargd_native));
+ if (argtype->xtype != NULL)
+ strlcpy(desc->dtargd_xlate, argtype->xtype,
+ sizeof(desc->dtargd_xlate));
}
- } else
- desc->dtargd_ndx = DTRACE_ARGNONE;
+ }
}
static void
sdt_destroy(void *arg, dtrace_id_t id, void *parg)
{
- struct sdt_probe *probe;
-
- probe = parg;
- TAILQ_REMOVE(&probe->prov->probe_list, probe, probe_entry);
}
/*
* Called from the kernel linker when a module is loaded, before
* dtrace_module_loaded() is called. This is done so that it's possible to
- * register new providers when modules are loaded. We cannot do this in the
- * provide_module method since it's called with the provider lock held
- * and dtrace_register() will try to acquire it again.
+ * register new providers when modules are loaded. The DTrace framework
+ * explicitly disallows calling into the framework from the provide_module
+ * provider method, so we cannot do this there.
*/
static void
sdt_kld_load(void *arg __unused, struct linker_file *lf)
@@ -264,14 +271,15 @@ sdt_kld_load(void *arg __unused, struct
}
static void
-sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error
__unused)
+sdt_kld_unload_try(void *arg __unused, struct linker_file *lf, int *error)
{
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,
NULL))
+ else if (linker_file_lookup_set(lf, "sdt_providers_set", &begin, &end,
+ NULL))
/* No DTrace providers are declared in this file. */
return;
@@ -281,17 +289,20 @@ sdt_kld_unload_try(void *arg __unused, s
*/
for (curr = begin; curr < end; curr++) {
TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
- if (strcmp(prov->name, (*curr)->name) == 0) {
- if (prov->sdt_refs == 1) {
- TAILQ_REMOVE(&sdt_prov_list, prov,
- prov_entry);
- dtrace_unregister(prov->id);
- free(prov->name, M_SDT);
- free(prov, M_SDT);
- } else
- prov->sdt_refs--;
- break;
- }
+ if (strcmp(prov->name, (*curr)->name) != 0)
+ continue;
+
+ if (prov->sdt_refs == 1) {
+ if (dtrace_unregister(prov->id) != 0) {
+ *error = 1;
+ return;
+ }
+ TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
+ free(prov->name, M_SDT);
+ free(prov, M_SDT);
+ } else
+ prov->sdt_refs--;
+ break;
}
}
}
@@ -306,15 +317,11 @@ sdt_linker_file_cb(linker_file_t lf, voi
}
static void
-sdt_load(void *arg __unused)
+sdt_load()
{
TAILQ_INIT(&sdt_prov_list);
- /* Create the /dev/dtrace/sdt entry. */
- sdt_cdev = make_dev(&sdt_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600,
- "dtrace/sdt");
-
sdt_probe_func = dtrace_probe;
sdt_kld_load_tag = EVENTHANDLER_REGISTER(kld_load, sdt_kld_load, NULL,
@@ -327,9 +334,10 @@ sdt_load(void *arg __unused)
}
static int
-sdt_unload(void *arg __unused)
+sdt_unload()
{
struct sdt_provider *prov, *tmp;
+ int ret;
EVENTHANDLER_DEREGISTER(kld_load, sdt_kld_load_tag);
EVENTHANDLER_DEREGISTER(kld_unload_try, sdt_kld_unload_try_tag);
@@ -337,18 +345,17 @@ sdt_unload(void *arg __unused)
sdt_probe_func = sdt_probe_stub;
TAILQ_FOREACH_SAFE(prov, &sdt_prov_list, prov_entry, tmp) {
+ ret = dtrace_unregister(prov->id);
+ if (ret != 0)
+ return (ret);
TAILQ_REMOVE(&sdt_prov_list, prov, prov_entry);
- dtrace_unregister(prov->id);
free(prov->name, M_SDT);
free(prov, M_SDT);
}
- destroy_dev(sdt_cdev);
-
return (0);
}
-/* ARGSUSED */
static int
sdt_modevent(module_t mod __unused, int type, void *data __unused)
{
@@ -356,9 +363,11 @@ sdt_modevent(module_t mod __unused, int
switch (type) {
case MOD_LOAD:
+ sdt_load();
break;
case MOD_UNLOAD:
+ error = sdt_unload();
break;
case MOD_SHUTDOWN:
@@ -372,18 +381,6 @@ sdt_modevent(module_t mod __unused, int
return (error);
}
-/* ARGSUSED */
-static int
-sdt_open(struct cdev *dev __unused, int oflags __unused, int devtype __unused,
- struct thread *td __unused)
-{
-
- return (0);
-}
-
-SYSINIT(sdt_load, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_load, NULL);
-SYSUNINIT(sdt_unload, SI_SUB_DTRACE_PROVIDER, SI_ORDER_ANY, sdt_unload, NULL);
-
DEV_MODULE(sdt, sdt_modevent, NULL);
MODULE_VERSION(sdt, 1);
MODULE_DEPEND(sdt, dtrace, 1, 1, 1);
Modified: stable/9/sys/sys/sdt.h
==============================================================================
--- stable/9/sys/sys/sdt.h Mon Feb 17 12:48:05 2014 (r262040)
+++ stable/9/sys/sys/sdt.h Mon Feb 17 12:48:19 2014 (r262041)
@@ -134,7 +134,7 @@ SET_DECLARE(sdt_argtypes_set, struct sdt
#define SDT_PROVIDER_DEFINE(prov)
\
struct sdt_provider sdt_provider_##prov[1] = {
\
- { #prov, { NULL, NULL }, { NULL, NULL }, 0, 0 }
\
+ { #prov, { NULL, NULL }, 0, 0 }
\
};
\
DATA_SET(sdt_providers_set, sdt_provider_##prov);
@@ -358,7 +358,6 @@ struct sdt_provider {
char *name; /* Provider name. */
TAILQ_ENTRY(sdt_provider)
prov_entry; /* SDT provider list entry. */
- TAILQ_HEAD(probe_list_head, sdt_probe) probe_list;
uintptr_t id; /* DTrace provider ID. */
int sdt_refs; /* Number of module references. */
};
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