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ftrace: add necessary locking for ftrace records

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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: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-08-15 21:40:05 -04:00 committed by Ingo Molnar
parent 00fd61aee1
commit 99ecdc43bc
1 changed files with 30 additions and 14 deletions
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44
kernel/trace/ftrace.c
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@ -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);