Commit 99ecdc43 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: add necessary locking for ftrace records 



The new design of pre-recorded mcounts and updating the code outside of
kstop_machine has changed the way the records themselves are protected.

This patch uses the ftrace_lock to protect the records. Note, the lock
still does not need to be taken within calls that are only called via
kstop_machine, since the that code can not run while the spin lock is held.

Also removed the hash_lock needed for the daemon when MCOUNT_RECORD is
configured. Also did a slight cleanup of an unused variable.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 00fd61ae

kernel/trace/ftrace.c

+30 −14
Original line number Diff line number Diff line
@@ -81,7 +81,7 @@ void clear_ftrace_function(void) 


static int __register_ftrace_function(struct ftrace_ops *ops)

{

	/* Should never be called by interrupts */

	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);



	ops->next = ftrace_list;
@@ -115,6 +115,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) 
	struct ftrace_ops **p;

	int ret = 0;



	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);



	/*
@@ -153,6 +154,21 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) 


#ifdef CONFIG_DYNAMIC_FTRACE



#ifndef CONFIG_FTRACE_MCOUNT_RECORD

/*

 * The hash lock is only needed when the recording of the mcount

 * callers are dynamic. That is, by the caller themselves and

 * not recorded via the compilation.

 */

static DEFINE_SPINLOCK(ftrace_hash_lock);

#define ftrace_hash_lock(flags)	  spin_lock_irqsave(ftrace_hash_lock, flags)

#define ftrace_hash_unlock(flags) spin_lock_irqsave(ftrace_hash_lock, flags)

#else

/* This is protected via the ftrace_lock with MCOUNT_RECORD. */

#define ftrace_hash_lock(flags)   do { (void)flags; } while (0)

#define ftrace_hash_unlock(flags) do { } while(0)

#endif



static struct task_struct *ftraced_task;



enum {
@@ -171,7 +187,6 @@ static struct hlist_head ftrace_hash[FTRACE_HASHSIZE]; 


static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);



static DEFINE_SPINLOCK(ftrace_shutdown_lock);

static DEFINE_MUTEX(ftraced_lock);

static DEFINE_MUTEX(ftrace_regex_lock);
@@ -310,7 +325,7 @@ void ftrace_release(void *start, unsigned long size) 
	if (ftrace_disabled || !start)

		return;



	/* No interrupt should call this */

	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);



	for (pg = ftrace_pages_start; pg; pg = pg->next) {
@@ -362,7 +377,6 @@ ftrace_record_ip(unsigned long ip) 
	unsigned long flags;

	unsigned long key;

	int resched;

	int atomic;

	int cpu;



	if (!ftrace_enabled || ftrace_disabled)
@@ -392,9 +406,7 @@ ftrace_record_ip(unsigned long ip) 
	if (ftrace_ip_in_hash(ip, key))

		goto out;



	atomic = irqs_disabled();



	spin_lock_irqsave(&ftrace_shutdown_lock, flags);

	ftrace_hash_lock(flags);



	/* This ip may have hit the hash before the lock */

	if (ftrace_ip_in_hash(ip, key))
@@ -411,7 +423,7 @@ ftrace_record_ip(unsigned long ip) 
	ftraced_trigger = 1;



 out_unlock:

	spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);

	ftrace_hash_unlock(flags);

 out:

	per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
@@ -887,6 +899,8 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 


	(*pos)++;



	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);

 retry:

	if (iter->idx >= iter->pg->index) {

		if (iter->pg->next) {
@@ -910,6 +924,7 @@ t_next(struct seq_file *m, void *v, loff_t *pos) 
			goto retry;

		}

	}

	spin_unlock(&ftrace_lock);



	iter->pos = *pos;
@@ -1023,8 +1038,8 @@ static void ftrace_filter_reset(int enable) 
	unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

	unsigned i;



	/* keep kstop machine from running */

	preempt_disable();

	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);

	if (enable)

		ftrace_filtered = 0;

	pg = ftrace_pages_start;
@@ -1037,7 +1052,7 @@ static void ftrace_filter_reset(int enable) 
		}

		pg = pg->next;

	}

	preempt_enable();

	spin_unlock(&ftrace_lock);

}



static int
@@ -1149,8 +1164,8 @@ ftrace_match(unsigned char *buff, int len, int enable) 
		}

	}



	/* keep kstop machine from running */

	preempt_disable();

	/* should not be called from interrupt context */

	spin_lock(&ftrace_lock);

	if (enable)

		ftrace_filtered = 1;

	pg = ftrace_pages_start;
@@ -1187,7 +1202,7 @@ ftrace_match(unsigned char *buff, int len, int enable) 
		}

		pg = pg->next;

	}

	preempt_enable();

	spin_unlock(&ftrace_lock);

}



static ssize_t
@@ -1551,6 +1566,7 @@ static int ftrace_convert_nops(unsigned long *start, 
	p = start;

	while (p < end) {

		addr = ftrace_call_adjust(*p++);

		/* should not be called from interrupt context */

		spin_lock(&ftrace_lock);

		ftrace_record_ip(addr);

		spin_unlock(&ftrace_lock);

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