Signed-off-by: Mathieu Desnoyers <[email protected]>
---
instrumentation/Makefile | 1
instrumentation/marker.c | 525 +++++++++++++++++++++++++++++++++++++++++++++++
kernel/Makefile | 1
kernel/marker.c | 525 -----------------------------------------------
4 files changed, 526 insertions(+), 526 deletions(-)
Index: linux-2.6-lttng.stable/instrumentation/Makefile
===================================================================
--- linux-2.6-lttng.stable.orig/instrumentation/Makefile 2007-10-29 09:51:46.000000000 -0400
+++ linux-2.6-lttng.stable/instrumentation/Makefile 2007-10-29 09:52:09.000000000 -0400
@@ -3,3 +3,4 @@
#
obj-$(CONFIG_KPROBES) += kprobes.o
+obj-$(CONFIG_MARKERS) += marker.o
Index: linux-2.6-lttng.stable/instrumentation/marker.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6-lttng.stable/instrumentation/marker.c 2007-10-29 09:51:51.000000000 -0400
@@ -0,0 +1,525 @@
+/*
+ * Copyright (C) 2007 Mathieu Desnoyers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/jhash.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+#include <linux/marker.h>
+#include <linux/err.h>
+
+extern struct marker __start___markers[];
+extern struct marker __stop___markers[];
+
+/*
+ * module_mutex nests inside markers_mutex. Markers mutex protects the builtin
+ * and module markers, the hash table and deferred_sync.
+ */
+static DEFINE_MUTEX(markers_mutex);
+
+/*
+ * Marker deferred synchronization.
+ * Upon marker probe_unregister, we delay call to synchronize_sched() to
+ * accelerate mass unregistration (only when there is no more reference to a
+ * given module do we call synchronize_sched()). However, we need to make sure
+ * every critical region has ended before we re-arm a marker that has been
+ * unregistered and then registered back with a different probe data.
+ */
+static int deferred_sync;
+
+/*
+ * Marker hash table, containing the active markers.
+ * Protected by module_mutex.
+ */
+#define MARKER_HASH_BITS 6
+#define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS)
+
+struct marker_entry {
+ struct hlist_node hlist;
+ char *format;
+ marker_probe_func *probe;
+ void *private;
+ int refcount; /* Number of times armed. 0 if disarmed. */
+ char name[0]; /* Contains name'\0'format'\0' */
+};
+
+static struct hlist_head marker_table[MARKER_TABLE_SIZE];
+
+/**
+ * __mark_empty_function - Empty probe callback
+ * @mdata: pointer of type const struct marker
+ * @fmt: format string
+ * @...: variable argument list
+ *
+ * Empty callback provided as a probe to the markers. By providing this to a
+ * disabled marker, we make sure the execution flow is always valid even
+ * though the function pointer change and the marker enabling are two distinct
+ * operations that modifies the execution flow of preemptible code.
+ */
+void __mark_empty_function(const struct marker *mdata, void *private,
+ const char *fmt, ...)
+{
+}
+EXPORT_SYMBOL_GPL(__mark_empty_function);
+
+/*
+ * Get marker if the marker is present in the marker hash table.
+ * Must be called with markers_mutex held.
+ * Returns NULL if not present.
+ */
+static struct marker_entry *get_marker(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ u32 hash = jhash(name, strlen(name), 0);
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name))
+ return e;
+ }
+ return NULL;
+}
+
+/*
+ * Add the marker to the marker hash table. Must be called with markers_mutex
+ * held.
+ */
+static int add_marker(const char *name, const char *format,
+ marker_probe_func *probe, void *private)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ size_t name_len = strlen(name) + 1;
+ size_t format_len = 0;
+ u32 hash = jhash(name, name_len-1, 0);
+
+ if (format)
+ format_len = strlen(format) + 1;
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ printk(KERN_NOTICE
+ "Marker %s busy, probe %p already installed\n",
+ name, e->probe);
+ return -EBUSY; /* Already there */
+ }
+ }
+ /*
+ * Using kmalloc here to allocate a variable length element. Could
+ * cause some memory fragmentation if overused.
+ */
+ e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
+ GFP_KERNEL);
+ if (!e)
+ return -ENOMEM;
+ memcpy(&e->name[0], name, name_len);
+ if (format) {
+ e->format = &e->name[name_len];
+ memcpy(e->format, format, format_len);
+ trace_mark(core_marker_format, "name %s format %s",
+ e->name, e->format);
+ } else
+ e->format = NULL;
+ e->probe = probe;
+ e->private = private;
+ e->refcount = 0;
+ hlist_add_head(&e->hlist, head);
+ return 0;
+}
+
+/*
+ * Remove the marker from the marker hash table. Must be called with mutex_lock
+ * held.
+ */
+static void *remove_marker(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ int found = 0;
+ size_t len = strlen(name) + 1;
+ void *private = NULL;
+ u32 hash = jhash(name, len-1, 0);
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ found = 1;
+ break;
+ }
+ }
+ if (found) {
+ private = e->private;
+ hlist_del(&e->hlist);
+ kfree(e);
+ }
+ return private;
+}
+
+/*
+ * Set the mark_entry format to the format found in the element.
+ */
+static int marker_set_format(struct marker_entry **entry, const char *format)
+{
+ struct marker_entry *e;
+ size_t name_len = strlen((*entry)->name) + 1;
+ size_t format_len = strlen(format) + 1;
+
+ e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
+ GFP_KERNEL);
+ if (!e)
+ return -ENOMEM;
+ memcpy(&e->name[0], (*entry)->name, name_len);
+ e->format = &e->name[name_len];
+ memcpy(e->format, format, format_len);
+ e->probe = (*entry)->probe;
+ e->private = (*entry)->private;
+ e->refcount = (*entry)->refcount;
+ hlist_add_before(&e->hlist, &(*entry)->hlist);
+ hlist_del(&(*entry)->hlist);
+ kfree(*entry);
+ *entry = e;
+ trace_mark(core_marker_format, "name %s format %s",
+ e->name, e->format);
+ return 0;
+}
+
+/*
+ * Sets the probe callback corresponding to one marker.
+ */
+static int set_marker(struct marker_entry **entry, struct marker *elem)
+{
+ int ret;
+ WARN_ON(strcmp((*entry)->name, elem->name) != 0);
+
+ if ((*entry)->format) {
+ if (strcmp((*entry)->format, elem->format) != 0) {
+ printk(KERN_NOTICE
+ "Format mismatch for probe %s "
+ "(%s), marker (%s)\n",
+ (*entry)->name,
+ (*entry)->format,
+ elem->format);
+ return -EPERM;
+ }
+ } else {
+ ret = marker_set_format(entry, elem->format);
+ if (ret)
+ return ret;
+ }
+ elem->call = (*entry)->probe;
+ elem->private = (*entry)->private;
+ elem->state = 1;
+ return 0;
+}
+
+/*
+ * Disable a marker and its probe callback.
+ * Note: only after a synchronize_sched() issued after setting elem->call to the
+ * empty function insures that the original callback is not used anymore. This
+ * insured by preemption disabling around the call site.
+ */
+static void disable_marker(struct marker *elem)
+{
+ elem->state = 0;
+ elem->call = __mark_empty_function;
+ /*
+ * Leave the private data and id there, because removal is racy and
+ * should be done only after a synchronize_sched(). These are never used
+ * until the next initialization anyway.
+ */
+}
+
+/**
+ * marker_update_probe_range - Update a probe range
+ * @begin: beginning of the range
+ * @end: end of the range
+ * @probe_module: module address of the probe being updated
+ * @refcount: number of references left to the given probe_module (out)
+ *
+ * Updates the probe callback corresponding to a range of markers.
+ * Must be called with markers_mutex held.
+ */
+void marker_update_probe_range(struct marker *begin,
+ struct marker *end, struct module *probe_module,
+ int *refcount)
+{
+ struct marker *iter;
+ struct marker_entry *mark_entry;
+
+ for (iter = begin; iter < end; iter++) {
+ mark_entry = get_marker(iter->name);
+ if (mark_entry && mark_entry->refcount) {
+ set_marker(&mark_entry, iter);
+ /*
+ * ignore error, continue
+ */
+ if (probe_module)
+ if (probe_module ==
+ __module_text_address((unsigned long)mark_entry->probe))
+ (*refcount)++;
+ } else {
+ disable_marker(iter);
+ }
+ }
+}
+
+/*
+ * Update probes, removing the faulty probes.
+ * Issues a synchronize_sched() when no reference to the module passed
+ * as parameter is found in the probes so the probe module can be
+ * safely unloaded from now on.
+ */
+static void marker_update_probes(struct module *probe_module)
+{
+ int refcount = 0;
+
+ mutex_lock(&markers_mutex);
+ /* Core kernel markers */
+ marker_update_probe_range(__start___markers,
+ __stop___markers, probe_module, &refcount);
+ /* Markers in modules. */
+ module_update_markers(probe_module, &refcount);
+ if (probe_module && refcount == 0) {
+ synchronize_sched();
+ deferred_sync = 0;
+ }
+ mutex_unlock(&markers_mutex);
+}
+
+/**
+ * marker_probe_register - Connect a probe to a marker
+ * @name: marker name
+ * @format: format string
+ * @probe: probe handler
+ * @private: probe private data
+ *
+ * private data must be a valid allocated memory address, or NULL.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_probe_register(const char *name, const char *format,
+ marker_probe_func *probe, void *private)
+{
+ struct marker_entry *entry;
+ int ret = 0, need_update = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = get_marker(name);
+ if (entry && entry->refcount) {
+ ret = -EBUSY;
+ goto end;
+ }
+ if (deferred_sync) {
+ synchronize_sched();
+ deferred_sync = 0;
+ }
+ ret = add_marker(name, format, probe, private);
+ if (ret)
+ goto end;
+ need_update = 1;
+end:
+ mutex_unlock(&markers_mutex);
+ if (need_update)
+ marker_update_probes(NULL);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_probe_register);
+
+/**
+ * marker_probe_unregister - Disconnect a probe from a marker
+ * @name: marker name
+ *
+ * Returns the private data given to marker_probe_register, or an ERR_PTR().
+ */
+void *marker_probe_unregister(const char *name)
+{
+ struct module *probe_module;
+ struct marker_entry *entry;
+ void *private;
+ int need_update = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = get_marker(name);
+ if (!entry) {
+ private = ERR_PTR(-ENOENT);
+ goto end;
+ }
+ entry->refcount = 0;
+ /* In what module is the probe handler ? */
+ probe_module = __module_text_address((unsigned long)entry->probe);
+ private = remove_marker(name);
+ deferred_sync = 1;
+ need_update = 1;
+end:
+ mutex_unlock(&markers_mutex);
+ if (need_update)
+ marker_update_probes(probe_module);
+ return private;
+}
+EXPORT_SYMBOL_GPL(marker_probe_unregister);
+
+/**
+ * marker_probe_unregister_private_data - Disconnect a probe from a marker
+ * @private: probe private data
+ *
+ * Unregister a marker by providing the registered private data.
+ * Returns the private data given to marker_probe_register, or an ERR_PTR().
+ */
+void *marker_probe_unregister_private_data(void *private)
+{
+ struct module *probe_module;
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *entry;
+ int found = 0;
+ unsigned int i;
+ int need_update = 0;
+
+ mutex_lock(&markers_mutex);
+ for (i = 0; i < MARKER_TABLE_SIZE; i++) {
+ head = &marker_table[i];
+ hlist_for_each_entry(entry, node, head, hlist) {
+ if (entry->private == private) {
+ found = 1;
+ goto iter_end;
+ }
+ }
+ }
+iter_end:
+ if (!found) {
+ private = ERR_PTR(-ENOENT);
+ goto end;
+ }
+ entry->refcount = 0;
+ /* In what module is the probe handler ? */
+ probe_module = __module_text_address((unsigned long)entry->probe);
+ private = remove_marker(entry->name);
+ deferred_sync = 1;
+ need_update = 1;
+end:
+ mutex_unlock(&markers_mutex);
+ if (need_update)
+ marker_update_probes(probe_module);
+ return private;
+}
+EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
+
+/**
+ * marker_arm - Arm a marker
+ * @name: marker name
+ *
+ * Activate a marker. It keeps a reference count of the number of
+ * arming/disarming done.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_arm(const char *name)
+{
+ struct marker_entry *entry;
+ int ret = 0, need_update = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = get_marker(name);
+ if (!entry) {
+ ret = -ENOENT;
+ goto end;
+ }
+ /*
+ * Only need to update probes when refcount passes from 0 to 1.
+ */
+ if (entry->refcount++)
+ goto end;
+ need_update = 1;
+end:
+ mutex_unlock(&markers_mutex);
+ if (need_update)
+ marker_update_probes(NULL);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_arm);
+
+/**
+ * marker_disarm - Disarm a marker
+ * @name: marker name
+ *
+ * Disarm a marker. It keeps a reference count of the number of arming/disarming
+ * done.
+ * Returns 0 if ok, error value on error.
+ */
+int marker_disarm(const char *name)
+{
+ struct marker_entry *entry;
+ int ret = 0, need_update = 0;
+
+ mutex_lock(&markers_mutex);
+ entry = get_marker(name);
+ if (!entry) {
+ ret = -ENOENT;
+ goto end;
+ }
+ /*
+ * Only permit decrement refcount if higher than 0.
+ * Do probe update only on 1 -> 0 transition.
+ */
+ if (entry->refcount) {
+ if (--entry->refcount)
+ goto end;
+ } else {
+ ret = -EPERM;
+ goto end;
+ }
+ need_update = 1;
+end:
+ mutex_unlock(&markers_mutex);
+ if (need_update)
+ marker_update_probes(NULL);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(marker_disarm);
+
+/**
+ * marker_get_private_data - Get a marker's probe private data
+ * @name: marker name
+ *
+ * Returns the private data pointer, or an ERR_PTR.
+ * The private data pointer should _only_ be dereferenced if the caller is the
+ * owner of the data, or its content could vanish. This is mostly used to
+ * confirm that a caller is the owner of a registered probe.
+ */
+void *marker_get_private_data(const char *name)
+{
+ struct hlist_head *head;
+ struct hlist_node *node;
+ struct marker_entry *e;
+ size_t name_len = strlen(name) + 1;
+ u32 hash = jhash(name, name_len-1, 0);
+ int found = 0;
+
+ head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ hlist_for_each_entry(e, node, head, hlist) {
+ if (!strcmp(name, e->name)) {
+ found = 1;
+ return e->private;
+ }
+ }
+ return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL_GPL(marker_get_private_data);
Index: linux-2.6-lttng.stable/kernel/Makefile
===================================================================
--- linux-2.6-lttng.stable.orig/kernel/Makefile 2007-10-29 09:51:38.000000000 -0400
+++ linux-2.6-lttng.stable/kernel/Makefile 2007-10-29 09:51:51.000000000 -0400
@@ -56,7 +56,6 @@ obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_SYSCTL) += utsname_sysctl.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o
-obj-$(CONFIG_MARKERS) += marker.o
ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <[email protected]>, the -fno-omit-frame-pointer is
Index: linux-2.6-lttng.stable/kernel/marker.c
===================================================================
--- linux-2.6-lttng.stable.orig/kernel/marker.c 2007-10-29 09:51:06.000000000 -0400
+++ /dev/null 1970-01-01 00:00:00.000000000 +0000
@@ -1,525 +0,0 @@
-/*
- * Copyright (C) 2007 Mathieu Desnoyers
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
- */
-#include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/types.h>
-#include <linux/jhash.h>
-#include <linux/list.h>
-#include <linux/rcupdate.h>
-#include <linux/marker.h>
-#include <linux/err.h>
-
-extern struct marker __start___markers[];
-extern struct marker __stop___markers[];
-
-/*
- * module_mutex nests inside markers_mutex. Markers mutex protects the builtin
- * and module markers, the hash table and deferred_sync.
- */
-static DEFINE_MUTEX(markers_mutex);
-
-/*
- * Marker deferred synchronization.
- * Upon marker probe_unregister, we delay call to synchronize_sched() to
- * accelerate mass unregistration (only when there is no more reference to a
- * given module do we call synchronize_sched()). However, we need to make sure
- * every critical region has ended before we re-arm a marker that has been
- * unregistered and then registered back with a different probe data.
- */
-static int deferred_sync;
-
-/*
- * Marker hash table, containing the active markers.
- * Protected by module_mutex.
- */
-#define MARKER_HASH_BITS 6
-#define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS)
-
-struct marker_entry {
- struct hlist_node hlist;
- char *format;
- marker_probe_func *probe;
- void *private;
- int refcount; /* Number of times armed. 0 if disarmed. */
- char name[0]; /* Contains name'\0'format'\0' */
-};
-
-static struct hlist_head marker_table[MARKER_TABLE_SIZE];
-
-/**
- * __mark_empty_function - Empty probe callback
- * @mdata: pointer of type const struct marker
- * @fmt: format string
- * @...: variable argument list
- *
- * Empty callback provided as a probe to the markers. By providing this to a
- * disabled marker, we make sure the execution flow is always valid even
- * though the function pointer change and the marker enabling are two distinct
- * operations that modifies the execution flow of preemptible code.
- */
-void __mark_empty_function(const struct marker *mdata, void *private,
- const char *fmt, ...)
-{
-}
-EXPORT_SYMBOL_GPL(__mark_empty_function);
-
-/*
- * Get marker if the marker is present in the marker hash table.
- * Must be called with markers_mutex held.
- * Returns NULL if not present.
- */
-static struct marker_entry *get_marker(const char *name)
-{
- struct hlist_head *head;
- struct hlist_node *node;
- struct marker_entry *e;
- u32 hash = jhash(name, strlen(name), 0);
-
- head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
- hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name))
- return e;
- }
- return NULL;
-}
-
-/*
- * Add the marker to the marker hash table. Must be called with markers_mutex
- * held.
- */
-static int add_marker(const char *name, const char *format,
- marker_probe_func *probe, void *private)
-{
- struct hlist_head *head;
- struct hlist_node *node;
- struct marker_entry *e;
- size_t name_len = strlen(name) + 1;
- size_t format_len = 0;
- u32 hash = jhash(name, name_len-1, 0);
-
- if (format)
- format_len = strlen(format) + 1;
- head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
- hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name)) {
- printk(KERN_NOTICE
- "Marker %s busy, probe %p already installed\n",
- name, e->probe);
- return -EBUSY; /* Already there */
- }
- }
- /*
- * Using kmalloc here to allocate a variable length element. Could
- * cause some memory fragmentation if overused.
- */
- e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
- GFP_KERNEL);
- if (!e)
- return -ENOMEM;
- memcpy(&e->name[0], name, name_len);
- if (format) {
- e->format = &e->name[name_len];
- memcpy(e->format, format, format_len);
- trace_mark(core_marker_format, "name %s format %s",
- e->name, e->format);
- } else
- e->format = NULL;
- e->probe = probe;
- e->private = private;
- e->refcount = 0;
- hlist_add_head(&e->hlist, head);
- return 0;
-}
-
-/*
- * Remove the marker from the marker hash table. Must be called with mutex_lock
- * held.
- */
-static void *remove_marker(const char *name)
-{
- struct hlist_head *head;
- struct hlist_node *node;
- struct marker_entry *e;
- int found = 0;
- size_t len = strlen(name) + 1;
- void *private = NULL;
- u32 hash = jhash(name, len-1, 0);
-
- head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
- hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name)) {
- found = 1;
- break;
- }
- }
- if (found) {
- private = e->private;
- hlist_del(&e->hlist);
- kfree(e);
- }
- return private;
-}
-
-/*
- * Set the mark_entry format to the format found in the element.
- */
-static int marker_set_format(struct marker_entry **entry, const char *format)
-{
- struct marker_entry *e;
- size_t name_len = strlen((*entry)->name) + 1;
- size_t format_len = strlen(format) + 1;
-
- e = kmalloc(sizeof(struct marker_entry) + name_len + format_len,
- GFP_KERNEL);
- if (!e)
- return -ENOMEM;
- memcpy(&e->name[0], (*entry)->name, name_len);
- e->format = &e->name[name_len];
- memcpy(e->format, format, format_len);
- e->probe = (*entry)->probe;
- e->private = (*entry)->private;
- e->refcount = (*entry)->refcount;
- hlist_add_before(&e->hlist, &(*entry)->hlist);
- hlist_del(&(*entry)->hlist);
- kfree(*entry);
- *entry = e;
- trace_mark(core_marker_format, "name %s format %s",
- e->name, e->format);
- return 0;
-}
-
-/*
- * Sets the probe callback corresponding to one marker.
- */
-static int set_marker(struct marker_entry **entry, struct marker *elem)
-{
- int ret;
- WARN_ON(strcmp((*entry)->name, elem->name) != 0);
-
- if ((*entry)->format) {
- if (strcmp((*entry)->format, elem->format) != 0) {
- printk(KERN_NOTICE
- "Format mismatch for probe %s "
- "(%s), marker (%s)\n",
- (*entry)->name,
- (*entry)->format,
- elem->format);
- return -EPERM;
- }
- } else {
- ret = marker_set_format(entry, elem->format);
- if (ret)
- return ret;
- }
- elem->call = (*entry)->probe;
- elem->private = (*entry)->private;
- elem->state = 1;
- return 0;
-}
-
-/*
- * Disable a marker and its probe callback.
- * Note: only after a synchronize_sched() issued after setting elem->call to the
- * empty function insures that the original callback is not used anymore. This
- * insured by preemption disabling around the call site.
- */
-static void disable_marker(struct marker *elem)
-{
- elem->state = 0;
- elem->call = __mark_empty_function;
- /*
- * Leave the private data and id there, because removal is racy and
- * should be done only after a synchronize_sched(). These are never used
- * until the next initialization anyway.
- */
-}
-
-/**
- * marker_update_probe_range - Update a probe range
- * @begin: beginning of the range
- * @end: end of the range
- * @probe_module: module address of the probe being updated
- * @refcount: number of references left to the given probe_module (out)
- *
- * Updates the probe callback corresponding to a range of markers.
- * Must be called with markers_mutex held.
- */
-void marker_update_probe_range(struct marker *begin,
- struct marker *end, struct module *probe_module,
- int *refcount)
-{
- struct marker *iter;
- struct marker_entry *mark_entry;
-
- for (iter = begin; iter < end; iter++) {
- mark_entry = get_marker(iter->name);
- if (mark_entry && mark_entry->refcount) {
- set_marker(&mark_entry, iter);
- /*
- * ignore error, continue
- */
- if (probe_module)
- if (probe_module ==
- __module_text_address((unsigned long)mark_entry->probe))
- (*refcount)++;
- } else {
- disable_marker(iter);
- }
- }
-}
-
-/*
- * Update probes, removing the faulty probes.
- * Issues a synchronize_sched() when no reference to the module passed
- * as parameter is found in the probes so the probe module can be
- * safely unloaded from now on.
- */
-static void marker_update_probes(struct module *probe_module)
-{
- int refcount = 0;
-
- mutex_lock(&markers_mutex);
- /* Core kernel markers */
- marker_update_probe_range(__start___markers,
- __stop___markers, probe_module, &refcount);
- /* Markers in modules. */
- module_update_markers(probe_module, &refcount);
- if (probe_module && refcount == 0) {
- synchronize_sched();
- deferred_sync = 0;
- }
- mutex_unlock(&markers_mutex);
-}
-
-/**
- * marker_probe_register - Connect a probe to a marker
- * @name: marker name
- * @format: format string
- * @probe: probe handler
- * @private: probe private data
- *
- * private data must be a valid allocated memory address, or NULL.
- * Returns 0 if ok, error value on error.
- */
-int marker_probe_register(const char *name, const char *format,
- marker_probe_func *probe, void *private)
-{
- struct marker_entry *entry;
- int ret = 0, need_update = 0;
-
- mutex_lock(&markers_mutex);
- entry = get_marker(name);
- if (entry && entry->refcount) {
- ret = -EBUSY;
- goto end;
- }
- if (deferred_sync) {
- synchronize_sched();
- deferred_sync = 0;
- }
- ret = add_marker(name, format, probe, private);
- if (ret)
- goto end;
- need_update = 1;
-end:
- mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
- return ret;
-}
-EXPORT_SYMBOL_GPL(marker_probe_register);
-
-/**
- * marker_probe_unregister - Disconnect a probe from a marker
- * @name: marker name
- *
- * Returns the private data given to marker_probe_register, or an ERR_PTR().
- */
-void *marker_probe_unregister(const char *name)
-{
- struct module *probe_module;
- struct marker_entry *entry;
- void *private;
- int need_update = 0;
-
- mutex_lock(&markers_mutex);
- entry = get_marker(name);
- if (!entry) {
- private = ERR_PTR(-ENOENT);
- goto end;
- }
- entry->refcount = 0;
- /* In what module is the probe handler ? */
- probe_module = __module_text_address((unsigned long)entry->probe);
- private = remove_marker(name);
- deferred_sync = 1;
- need_update = 1;
-end:
- mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(probe_module);
- return private;
-}
-EXPORT_SYMBOL_GPL(marker_probe_unregister);
-
-/**
- * marker_probe_unregister_private_data - Disconnect a probe from a marker
- * @private: probe private data
- *
- * Unregister a marker by providing the registered private data.
- * Returns the private data given to marker_probe_register, or an ERR_PTR().
- */
-void *marker_probe_unregister_private_data(void *private)
-{
- struct module *probe_module;
- struct hlist_head *head;
- struct hlist_node *node;
- struct marker_entry *entry;
- int found = 0;
- unsigned int i;
- int need_update = 0;
-
- mutex_lock(&markers_mutex);
- for (i = 0; i < MARKER_TABLE_SIZE; i++) {
- head = &marker_table[i];
- hlist_for_each_entry(entry, node, head, hlist) {
- if (entry->private == private) {
- found = 1;
- goto iter_end;
- }
- }
- }
-iter_end:
- if (!found) {
- private = ERR_PTR(-ENOENT);
- goto end;
- }
- entry->refcount = 0;
- /* In what module is the probe handler ? */
- probe_module = __module_text_address((unsigned long)entry->probe);
- private = remove_marker(entry->name);
- deferred_sync = 1;
- need_update = 1;
-end:
- mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(probe_module);
- return private;
-}
-EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
-
-/**
- * marker_arm - Arm a marker
- * @name: marker name
- *
- * Activate a marker. It keeps a reference count of the number of
- * arming/disarming done.
- * Returns 0 if ok, error value on error.
- */
-int marker_arm(const char *name)
-{
- struct marker_entry *entry;
- int ret = 0, need_update = 0;
-
- mutex_lock(&markers_mutex);
- entry = get_marker(name);
- if (!entry) {
- ret = -ENOENT;
- goto end;
- }
- /*
- * Only need to update probes when refcount passes from 0 to 1.
- */
- if (entry->refcount++)
- goto end;
- need_update = 1;
-end:
- mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
- return ret;
-}
-EXPORT_SYMBOL_GPL(marker_arm);
-
-/**
- * marker_disarm - Disarm a marker
- * @name: marker name
- *
- * Disarm a marker. It keeps a reference count of the number of arming/disarming
- * done.
- * Returns 0 if ok, error value on error.
- */
-int marker_disarm(const char *name)
-{
- struct marker_entry *entry;
- int ret = 0, need_update = 0;
-
- mutex_lock(&markers_mutex);
- entry = get_marker(name);
- if (!entry) {
- ret = -ENOENT;
- goto end;
- }
- /*
- * Only permit decrement refcount if higher than 0.
- * Do probe update only on 1 -> 0 transition.
- */
- if (entry->refcount) {
- if (--entry->refcount)
- goto end;
- } else {
- ret = -EPERM;
- goto end;
- }
- need_update = 1;
-end:
- mutex_unlock(&markers_mutex);
- if (need_update)
- marker_update_probes(NULL);
- return ret;
-}
-EXPORT_SYMBOL_GPL(marker_disarm);
-
-/**
- * marker_get_private_data - Get a marker's probe private data
- * @name: marker name
- *
- * Returns the private data pointer, or an ERR_PTR.
- * The private data pointer should _only_ be dereferenced if the caller is the
- * owner of the data, or its content could vanish. This is mostly used to
- * confirm that a caller is the owner of a registered probe.
- */
-void *marker_get_private_data(const char *name)
-{
- struct hlist_head *head;
- struct hlist_node *node;
- struct marker_entry *e;
- size_t name_len = strlen(name) + 1;
- u32 hash = jhash(name, name_len-1, 0);
- int found = 0;
-
- head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
- hlist_for_each_entry(e, node, head, hlist) {
- if (!strcmp(name, e->name)) {
- found = 1;
- return e->private;
- }
- }
- return ERR_PTR(-ENOENT);
-}
-EXPORT_SYMBOL_GPL(marker_get_private_data);
--
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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