unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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tracing: Clean up seqfile code for format file

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Remove the nasty hack that marks a pointer's LSB to distinguish common
fields from event fields. Replace it with a more sane approach.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4C6A23C2.9020606@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Li Zefan 2010-08-17 13:53:06 +08:00 committed by Steven Rostedt
parent 351af0725e
commit 86397dc3cc
1 changed files with 18 additions and 37 deletions
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55
kernel/trace/trace_events.c
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@ -600,21 +600,29 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
enum {
FORMAT_HEADER = 1,
FORMAT_PRINTFMT = 2,
FORMAT_FIELD_SEPERATOR = 2,
FORMAT_PRINTFMT = 3,
};
static void *f_next(struct seq_file *m, void *v, loff_t *pos)
{
struct ftrace_event_call *call = m->private;
struct ftrace_event_field *field;
struct list_head *head;
struct list_head *common_head = &ftrace_common_fields;
struct list_head *head = trace_get_fields(call);
(*pos)++;
switch ((unsigned long)v) {
case FORMAT_HEADER:
head = &ftrace_common_fields;
if (unlikely(list_empty(common_head)))
return NULL;
field = list_entry(common_head->prev,
struct ftrace_event_field, link);
return field;
case FORMAT_FIELD_SEPERATOR:
if (unlikely(list_empty(head)))
return NULL;
@ -626,31 +634,10 @@ static void *f_next(struct seq_file *m, void *v, loff_t *pos)
return NULL;
}
head = trace_get_fields(call);
/*
* To separate common fields from event fields, the
* LSB is set on the first event field. Clear it in case.
*/
v = (void *)((unsigned long)v & ~1L);
field = v;
/*
* If this is a common field, and at the end of the list, then
* continue with main list.
*/
if (field->link.prev == &ftrace_common_fields) {
if (unlikely(list_empty(head)))
return NULL;
field = list_entry(head->prev, struct ftrace_event_field, link);
/* Set the LSB to notify f_show to print an extra newline */
field = (struct ftrace_event_field *)
((unsigned long)field | 1);
return field;
}
/* If we are done tell f_show to print the format */
if (field->link.prev == head)
if (field->link.prev == common_head)
return (void *)FORMAT_FIELD_SEPERATOR;
else if (field->link.prev == head)
return (void *)FORMAT_PRINTFMT;
field = list_entry(field->link.prev, struct ftrace_event_field, link);
@ -688,22 +675,16 @@ static int f_show(struct seq_file *m, void *v)
seq_printf(m, "format:\n");
return 0;
case FORMAT_FIELD_SEPERATOR:
seq_putc(m, '\n');
return 0;
case FORMAT_PRINTFMT:
seq_printf(m, "\nprint fmt: %s\n",
call->print_fmt);
return 0;
}
/*
* To separate common fields from event fields, the
* LSB is set on the first event field. Clear it and
* print a newline if it is set.
*/
if ((unsigned long)v & 1) {
seq_putc(m, '\n');
v = (void *)((unsigned long)v & ~1L);
}
field = v;
/*