Commit 3d3800b4 authored by Nam Cao's avatar Nam Cao Committed by Steven Rostedt (Google)
Browse files

rv: Remove rv_reactor's reference counter 

rv_reactor has a reference counter to ensure it is not removed while
monitors are still using it.

However, this is futile, as __exit functions are not expected to fail and
will proceed normally despite rv_unregister_reactor() returning an error.

At the moment, reactors do not support being built as modules, therefore
they are never removed and the reference counters are not necessary.

If we support building RV reactors as modules in the future, kernel
module's centralized facilities such as try_module_get(), module_put() or
MODULE_SOFTDEP should be used instead of this custom implementation.

Remove this reference counter.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/bb946398436a5e17fb0f5b842ef3313c02291852.1753378331.git.namcao@linutronix.de


Reviewed-by: default avatarGabriele Monaco <gmonaco@redhat.com>
Signed-off-by: default avatarNam Cao <namcao@linutronix.de>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 3d3c3761

include/linux/rv.h

+0 −2
Original line number Diff line number Diff line
@@ -91,8 +91,6 @@ struct rv_reactor { 
	const char		*description;

	__printf(1, 2) void	(*react)(const char *msg, ...);

	struct list_head	list;

	/* protected by the monitor interface lock */

	int			counter;

};

#endif

kernel/trace/rv/rv.c

+0 −1
Original line number Diff line number Diff line
@@ -769,7 +769,6 @@ static const struct file_operations monitoring_on_fops = { 


static void destroy_monitor_dir(struct rv_monitor *mon)

{

	reactor_cleanup_monitor(mon);

	rv_remove(mon->root_d);

}

kernel/trace/rv/rv.h

+0 −6
Original line number Diff line number Diff line
@@ -31,7 +31,6 @@ bool rv_is_nested_monitor(struct rv_monitor *mon); 


#ifdef CONFIG_RV_REACTORS

int reactor_populate_monitor(struct rv_monitor *mon);

void reactor_cleanup_monitor(struct rv_monitor *mon);

int init_rv_reactors(struct dentry *root_dir);

#else

static inline int reactor_populate_monitor(struct rv_monitor *mon)
@@ -39,11 +38,6 @@ static inline int reactor_populate_monitor(struct rv_monitor *mon) 
	return 0;

}



static inline void reactor_cleanup_monitor(struct rv_monitor *mon)

{

	return;

}



static inline int init_rv_reactors(struct dentry *root_dir)

{

	return 0;

kernel/trace/rv/rv_reactors.c

+2 −31
Original line number Diff line number Diff line
@@ -172,10 +172,6 @@ static void monitor_swap_reactors_single(struct rv_monitor *mon, 
	if (monitor_enabled)

		rv_disable_monitor(mon);



	/* swap reactor's usage */

	mon->reactor->counter--;

	reactor->counter++;



	mon->reactor = reactor;

	mon->reacting = reacting;

	mon->react = reactor->react;
@@ -343,23 +339,10 @@ int rv_register_reactor(struct rv_reactor *reactor) 
 */

int rv_unregister_reactor(struct rv_reactor *reactor)

{

	int ret = 0;



	mutex_lock(&rv_interface_lock);



	if (!reactor->counter) {

	list_del(&reactor->list);

	} else {

		printk(KERN_WARNING

		       "rv: the rv_reactor %s is in use by %d monitor(s)\n",

		       reactor->name, reactor->counter);

		printk(KERN_WARNING "rv: the rv_reactor %s cannot be removed\n",

		       reactor->name);

		ret = -EBUSY;

	}



	mutex_unlock(&rv_interface_lock);

	return ret;

	return 0;

}



/*
@@ -456,23 +439,11 @@ int reactor_populate_monitor(struct rv_monitor *mon) 
	 * Configure as the rv_nop reactor.

	 */

	mon->reactor = get_reactor_rdef_by_name("nop");

	mon->reactor->counter++;

	mon->reacting = false;



	return 0;

}



/**

 * reactor_cleanup_monitor - cleanup a monitor reference

 * @mon:       the monitor.

 */

void reactor_cleanup_monitor(struct rv_monitor *mon)

{

	lockdep_assert_held(&rv_interface_lock);

	mon->reactor->counter--;

	WARN_ON_ONCE(mon->reactor->counter < 0);

}



/*

 * Nop reactor register

 */