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Commit 0eec481e authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Ingo Molnar
Browse files

markers: simplify marker_set_format() 



current marker_set_format() is complex this patch simplify it,
and decrease the overhead of marker_update_probes().

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent f8d56f17

kernel/marker.c

+25 −46
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ struct marker_entry { 
	void *oldptr;

	int rcu_pending;

	unsigned char ptype:1;

	unsigned char format_allocated:1;

	char name[0];	/* Contains name'\0'format'\0' */

};
@@ -416,6 +417,7 @@ static struct marker_entry *add_marker(const char *name, const char *format) 
	e->single.probe_private = NULL;

	e->multi = NULL;

	e->ptype = 0;

	e->format_allocated = 0;

	e->refcount = 0;

	e->rcu_pending = 0;

	hlist_add_head(&e->hlist, head);
@@ -447,6 +449,8 @@ static int remove_marker(const char *name) 
	if (e->single.func != __mark_empty_function)

		return -EBUSY;

	hlist_del(&e->hlist);

	if (e->format_allocated)

		kfree(e->format);

	/* Make sure the call_rcu has been executed */

	if (e->rcu_pending)

		rcu_barrier_sched();
@@ -457,57 +461,34 @@ static int remove_marker(const char *name) 
/*

 * Set the mark_entry format to the format found in the element.

 */

static int marker_set_format(struct marker_entry **entry, const char *format)

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)

	entry->format = kstrdup(format, GFP_KERNEL);

	if (!entry->format)

		return -ENOMEM;

	memcpy(&e->name[0], (*entry)->name, name_len);

	e->format = &e->name[name_len];

	memcpy(e->format, format, format_len);

	if (strcmp(e->format, MARK_NOARGS) == 0)

		e->call = marker_probe_cb_noarg;

	else

		e->call = marker_probe_cb;

	e->single = (*entry)->single;

	e->multi = (*entry)->multi;

	e->ptype = (*entry)->ptype;

	e->refcount = (*entry)->refcount;

	e->rcu_pending = 0;

	hlist_add_before(&e->hlist, &(*entry)->hlist);

	hlist_del(&(*entry)->hlist);

	/* Make sure the call_rcu has been executed */

	if ((*entry)->rcu_pending)

		rcu_barrier_sched();

	kfree(*entry);

	*entry = e;

	entry->format_allocated = 1;



	trace_mark(core_marker_format, "name %s format %s",

			e->name, e->format);

			entry->name, entry->format);

	return 0;

}



/*

 * Sets the probe callback corresponding to one marker.

 */

static int set_marker(struct marker_entry **entry, struct marker *elem,

static int set_marker(struct marker_entry *entry, struct marker *elem,

		int active)

{

	int ret;

	WARN_ON(strcmp((*entry)->name, elem->name) != 0);

	WARN_ON(strcmp(entry->name, elem->name) != 0);



	if ((*entry)->format) {

		if (strcmp((*entry)->format, elem->format) != 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,

				entry->name,

				entry->format,

				elem->format);

			return -EPERM;

		}
@@ -523,34 +504,33 @@ static int set_marker(struct marker_entry **entry, struct marker *elem, 
	 * pass from a "safe" callback (with argument) to an "unsafe"

	 * callback (does not set arguments).

	 */

	elem->call = (*entry)->call;

	elem->call = entry->call;

	/*

	 * Sanity check :

	 * We only update the single probe private data when the ptr is

	 * set to a _non_ single probe! (0 -> 1 and N -> 1, N != 1)

	 */

	WARN_ON(elem->single.func != __mark_empty_function

		&& elem->single.probe_private

		!= (*entry)->single.probe_private &&

		!elem->ptype);

	elem->single.probe_private = (*entry)->single.probe_private;

		&& elem->single.probe_private != entry->single.probe_private

		&& !elem->ptype);

	elem->single.probe_private = entry->single.probe_private;

	/*

	 * Make sure the private data is valid when we update the

	 * single probe ptr.

	 */

	smp_wmb();

	elem->single.func = (*entry)->single.func;

	elem->single.func = entry->single.func;

	/*

	 * We also make sure that the new probe callbacks array is consistent

	 * before setting a pointer to it.

	 */

	rcu_assign_pointer(elem->multi, (*entry)->multi);

	rcu_assign_pointer(elem->multi, entry->multi);

	/*

	 * Update the function or multi probe array pointer before setting the

	 * ptype.

	 */

	smp_wmb();

	elem->ptype = (*entry)->ptype;

	elem->ptype = entry->ptype;

	elem->state = active;



	return 0;
@@ -594,8 +574,7 @@ void marker_update_probe_range(struct marker *begin, 
	for (iter = begin; iter < end; iter++) {

		mark_entry = get_marker(iter->name);

		if (mark_entry) {

			set_marker(&mark_entry, iter,

					!!mark_entry->refcount);

			set_marker(mark_entry, iter, !!mark_entry->refcount);

			/*

			 * ignore error, continue

			 */
@@ -657,7 +636,7 @@ int marker_probe_register(const char *name, const char *format, 
			ret = PTR_ERR(entry);

	} else if (format) {

		if (!entry->format)

			ret = marker_set_format(&entry, format);

			ret = marker_set_format(entry, format);

		else if (strcmp(entry->format, format))

			ret = -EPERM;

	}