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authorRyan Stone <rstone@FreeBSD.org>2012-03-27 15:07:43 +0000
committerRyan Stone <rstone@FreeBSD.org>2012-03-27 15:07:43 +0000
commit974241079704e313fe2424a2c31e7e9342979ca7 (patch)
tree3e88342c0b877113ee02c840d3b675a1e232f253
parent250a19126063fc5d69757aaa927d6dbf04e91dc9 (diff)
downloadsrc-974241079704e313fe2424a2c31e7e9342979ca7.tar.gz
src-974241079704e313fe2424a2c31e7e9342979ca7.zip
Instead of only iterating over the set of known SDT probes when sdt.ko is
loaded and unloaded, also have sdt.ko register callbacks with kern_sdt.c that will be called when a newly loaded KLD module adds more probes or a module with probes is unloaded. This fixes two issues: first, if a module with SDT probes was loaded after sdt.ko was loaded, those new probes would not be available in DTrace. Second, if a module with SDT probes was unloaded while sdt.ko was loaded, the kernel would panic the next time DTrace had cause to try and do anything with the no-longer-existent probes. This makes it possible to create SDT probes in KLD modules, although there are still two caveats: first, any SDT probes in a KLD module must be part of a DTrace provider that is defined in that module. At present DTrace only destroys probes when the provider is destroyed, so you can still panic the system if a KLD module creates new probes in a provider from a different module(including the kernel) and then unload the the first module. Second, the system will panic if you unload a module containing SDT probes while there is an active D script that has enabled those probes. MFC after: 1 month
Notes
Notes: svn path=/head/; revision=233552
-rw-r--r--sys/cddl/dev/sdt/sdt.c7
-rw-r--r--sys/kern/kern_sdt.c74
-rw-r--r--sys/sys/sdt.h4
3 files changed, 79 insertions, 6 deletions
diff --git a/sys/cddl/dev/sdt/sdt.c b/sys/cddl/dev/sdt/sdt.c
index d5d41724593f..395daf7ec59a 100644
--- a/sys/cddl/dev/sdt/sdt.c
+++ b/sys/cddl/dev/sdt/sdt.c
@@ -52,6 +52,8 @@ static void sdt_destroy(void *, dtrace_id_t, void *);
static void sdt_enable(void *, dtrace_id_t, void *);
static void sdt_disable(void *, dtrace_id_t, void *);
static void sdt_load(void *);
+static int sdt_provider_unreg_callback(struct sdt_provider *prov,
+ void *arg);
static struct cdevsw sdt_cdevsw = {
.d_version = D_VERSION,
@@ -190,7 +192,8 @@ sdt_load(void *dummy)
sdt_probe_func = dtrace_probe;
- (void) sdt_provider_listall(sdt_provider_reg_callback, NULL);
+ sdt_register_callbacks(sdt_provider_reg_callback, NULL,
+ sdt_provider_unreg_callback, NULL, sdt_probe_callback, NULL);
}
static int
@@ -206,7 +209,7 @@ sdt_unload()
sdt_probe_func = sdt_probe_stub;
- (void) sdt_provider_listall(sdt_provider_unreg_callback, NULL);
+ sdt_deregister_callbacks();
destroy_dev(sdt_cdev);
diff --git a/sys/kern/kern_sdt.c b/sys/kern/kern_sdt.c
index 0702cc083601..ee4addee0c12 100644
--- a/sys/kern/kern_sdt.c
+++ b/sys/kern/kern_sdt.c
@@ -59,6 +59,16 @@ static struct sx sdt_sx;
*/
sdt_probe_func_t sdt_probe_func = sdt_probe_stub;
+static sdt_provider_listall_func_t sdt_provider_register_func = NULL;
+static sdt_provider_listall_func_t sdt_provider_deregister_func = NULL;
+static sdt_probe_listall_func_t sdt_probe_register_func = NULL;
+
+static void *sdt_provider_register_arg;
+static void *sdt_provider_deregister_arg;
+static void *sdt_probe_register_arg;
+
+static int sdt_provider_listall_locked(sdt_provider_listall_func_t, void *);
+
/*
* This is a stub for probe calls in case kernel DTrace support isn't
* compiled in. It should never get called because there is no DTrace
@@ -85,6 +95,9 @@ sdt_provider_register(void *arg)
TAILQ_INIT(&prov->probe_list);
+ if (sdt_provider_register_func != NULL)
+ sdt_provider_register_func(prov, sdt_provider_register_arg);
+
sx_xunlock(&sdt_sx);
}
@@ -100,6 +113,9 @@ sdt_provider_deregister(void *arg)
TAILQ_REMOVE(&sdt_provider_list, prov, prov_entry);
+ if (sdt_provider_deregister_func != NULL)
+ sdt_provider_deregister_func(prov, sdt_provider_deregister_arg);
+
sx_xunlock(&sdt_sx);
}
@@ -128,6 +144,9 @@ sdt_probe_register(void *arg)
probe->state = SDT_INIT;
+ if (sdt_probe_register_func != NULL)
+ sdt_probe_register_func(probe, sdt_provider_register_arg);
+
sx_xunlock(&sdt_sx);
}
@@ -203,20 +222,31 @@ SYSUNINIT(sdt, SI_SUB_KDTRACE, SI_ORDER_FIRST, sdt_uninit, NULL);
* List statically defined tracing providers.
*/
int
-sdt_provider_listall(sdt_provider_listall_func_t callback_func,void *arg)
+sdt_provider_listall(sdt_provider_listall_func_t callback_func, void *arg)
+{
+ int error;
+
+ sx_xlock(&sdt_sx);
+ error = sdt_provider_listall_locked(callback_func, arg);
+ sx_xunlock(&sdt_sx);
+
+ return (error);
+}
+
+static int
+sdt_provider_listall_locked(sdt_provider_listall_func_t callback_func,
+ void *arg)
{
int error = 0;
struct sdt_provider *prov;
- sx_xlock(&sdt_sx);
+ sx_assert(&sdt_sx, SX_XLOCKED);
TAILQ_FOREACH(prov, &sdt_provider_list, prov_entry) {
if ((error = callback_func(prov, arg)) != 0)
break;
}
- sx_xunlock(&sdt_sx);
-
return (error);
}
@@ -271,3 +301,39 @@ sdt_argtype_listall(struct sdt_probe *probe,
return (error);
}
+
+void sdt_register_callbacks(sdt_provider_listall_func_t register_prov,
+ void *reg_prov_arg, sdt_provider_listall_func_t deregister_prov,
+ void *dereg_prov_arg, sdt_probe_listall_func_t register_probe,
+ void * reg_probe_arg)
+{
+
+ sx_xlock(&sdt_sx);
+ sdt_provider_register_func = register_prov;
+ sdt_provider_deregister_func = deregister_prov;
+ sdt_probe_register_func = register_probe;
+
+ sdt_provider_register_arg = reg_prov_arg;
+ sdt_provider_deregister_arg = dereg_prov_arg;
+ sdt_probe_register_arg = reg_probe_arg;
+
+ sdt_provider_listall_locked(register_prov, reg_prov_arg);
+ sx_xunlock(&sdt_sx);
+}
+
+void sdt_deregister_callbacks(void)
+{
+
+ sx_xlock(&sdt_sx);
+ sdt_provider_listall_locked(sdt_provider_deregister_func,
+ sdt_provider_deregister_arg);
+
+ sdt_provider_register_func = NULL;
+ sdt_provider_deregister_func = NULL;
+ sdt_probe_register_func = NULL;
+
+ sdt_provider_register_arg = NULL;
+ sdt_provider_deregister_arg = NULL;
+ sdt_probe_register_arg = NULL;
+ sx_xunlock(&sdt_sx);
+}
diff --git a/sys/sys/sdt.h b/sys/sys/sdt.h
index 3ee18a8f672b..90d169906d49 100644
--- a/sys/sys/sdt.h
+++ b/sys/sys/sdt.h
@@ -258,6 +258,10 @@ int sdt_argtype_listall(struct sdt_probe *, sdt_argtype_listall_func_t, void *);
int sdt_probe_listall(struct sdt_provider *, sdt_probe_listall_func_t, void *);
int sdt_provider_listall(sdt_provider_listall_func_t,void *);
+void sdt_register_callbacks(sdt_provider_listall_func_t, void *,
+ sdt_provider_listall_func_t, void *, sdt_probe_listall_func_t, void *);
+void sdt_deregister_callbacks(void);
+
#endif /* KDTRACE_HOOKS */
#endif /* _KERNEL */