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ftrace: Create separate t_func_next() to simplify the function / hash logic 

I noticed that if I use dd to read the set_ftrace_filter file that the first
hash command is repeated.

 # cd /sys/kernel/debug/tracing
 # echo schedule > set_ftrace_filter
 # echo do_IRQ >> set_ftrace_filter
 # echo schedule:traceoff >> set_ftrace_filter
 # echo do_IRQ:traceoff >> set_ftrace_filter

 # cat set_ftrace_filter
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited

 # dd if=set_ftrace_filter bs=1
 schedule
 do_IRQ
 schedule:traceoff:unlimited
 schedule:traceoff:unlimited
 do_IRQ:traceoff:unlimited
 98+0 records in
 98+0 records out
 98 bytes copied, 0.00265011 s, 37.0 kB/s

This is due to the way t_start() calls t_next() as well as the seq_file
calls t_next() and the state is slightly different between the two. Namely,
t_start() will call t_next() with a local "pos" variable.

By separating out the function listing from t_next() into its own function,
we can have better control of outputting the functions and the hash of
triggers. This simplifies the code.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2017-03-29 22:45:18 -04:00
parent 43ff926a0c
commit 5bd84629a7
1 changed files with 31 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

45
kernel/trace/ftrace.c
View File

@ -3154,22 +3154,12 @@ t_hash_show(struct seq_file *m, struct ftrace_iterator *iter)
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
t_func_next(struct seq_file *m, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
struct dyn_ftrace *rec = NULL;
if (unlikely(ftrace_disabled))
return NULL;
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_next(m, pos);
(*pos)++;
iter->pos = iter->func_pos = *pos;
if (iter->flags & FTRACE_ITER_PRINTALL)
return t_hash_start(m, pos);
retry:
if (iter->idx >= iter->pg->index) {
@ -3192,13 +3182,40 @@ t_next(struct seq_file *m, void *v, loff_t *pos)
}
if (!rec)
return t_hash_start(m, pos);
return NULL;
iter->pos = iter->func_pos = *pos;
iter->func = rec;
return iter;
}
static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ftrace_iterator *iter = m->private;
void *ret;
if (unlikely(ftrace_disabled))
return NULL;
if (iter->flags & FTRACE_ITER_HASH)
return t_hash_next(m, pos);
if (iter->flags & FTRACE_ITER_PRINTALL) {
/* next must increment pos, and t_hash_start does not */
(*pos)++;
return t_hash_start(m, pos);
}
ret = t_func_next(m, pos);
if (!ret)
return t_hash_start(m, pos);
return ret;
}
static void reset_iter_read(struct ftrace_iterator *iter)
{
iter->pos = 0;
@ -3250,13 +3267,13 @@ static void *t_start(struct seq_file *m, loff_t *pos)
iter->pg = ftrace_pages_start;
iter->idx = 0;
for (l = 0; l <= *pos; ) {
p = t_next(m, p, &l);
p = t_func_next(m, &l);
if (!p)
break;
}
if (!p)
return NULL;
return t_hash_start(m, pos);
return iter;
}