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avoid repeated scans for goto targets (udev_iter_find_label)

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The scans are now performed up-front at parse-time, instead of being
repeated for each event at run-time.

Cachegrind reports a 5% reduction in cpu cycles
(excluding the time spent in-kernel).
This commit is contained in:
Alan Jenkins 2008-09-28 12:02:44 +01:00 committed by Kay Sievers
parent 669ed8675f
commit 41b7a00922
3 changed files with 45 additions and 12 deletions
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4
udev/udev_rules.c
View File

@ -1529,7 +1529,7 @@ int udev_rules_get_name(struct udev_rules *rules, struct udevice *udevice)
if (rule->goto_label.operation != KEY_OP_UNSET) {
dbg(udevice->udev, "moving forward to label '%s'\n", key_val(rule, &rule->goto_label));
udev_rules_iter_label(&iter, key_val(rule, &rule->goto_label));
udev_rules_iter_goto(&iter, rule->goto_rule_off);
}
}
}
@ -1609,7 +1609,7 @@ int udev_rules_get_run(struct udev_rules *rules, struct udevice *udevice)
if (rule->goto_label.operation != KEY_OP_UNSET) {
dbg(udevice->udev, "moving forward to label '%s'\n", key_val(rule, &rule->goto_label));
udev_rules_iter_label(&iter, key_val(rule, &rule->goto_label));
udev_rules_iter_goto(&iter, rule->goto_rule_off);
}
}
}

3
udev/udev_rules.h
View File

@ -84,6 +84,7 @@ struct udev_rule {
struct key wait_for;
struct key label;
struct key goto_label;
size_t goto_rule_off;
struct key name;
struct key symlink;
@ -122,7 +123,7 @@ extern void udev_rules_cleanup(struct udev_rules *rules);
extern void udev_rules_iter_init(struct udev_rules_iter *iter, struct udev_rules *rules);
extern struct udev_rule *udev_rules_iter_next(struct udev_rules_iter *iter);
extern struct udev_rule *udev_rules_iter_label(struct udev_rules_iter *iter, const char *label);
extern struct udev_rule *udev_rules_iter_goto(struct udev_rules_iter *iter, size_t rule_off);
extern int udev_rules_get_name(struct udev_rules *rules, struct udevice *udev);
extern int udev_rules_get_run(struct udev_rules *rules, struct udevice *udev);

50
udev/udev_rules_parse.c
View File

@ -58,29 +58,40 @@ struct udev_rule *udev_rules_iter_next(struct udev_rules_iter *iter)
return rule;
}
struct udev_rule *udev_rules_iter_label(struct udev_rules_iter *iter, const char *label)
struct udev_rule *udev_rules_iter_goto(struct udev_rules_iter *iter, size_t rule_off)
{
struct udev_rules *rules = iter->rules;
struct udev_rule *rule;
dbg(rules->udev "current=%zi\n", iter->current);
iter->current = rule_off;
rule = (struct udev_rule *) (rules->buf + iter->current);
return rule;
}
static size_t find_label(const struct udev_rules_iter *iter, const char *label)
{
struct udev_rule *rule;
struct udev_rules *rules = iter->rules;
size_t start = iter->current;
size_t current = iter->current;
next:
dbg(rules->udev, "current=%zi\n", iter->current);
if (iter->current >= rules->bufsize) {
dbg(rules->udev, "current=%zi\n", current);
if (current >= rules->bufsize) {
err(rules->udev, "LABEL='%s' not found, GOTO will be ignored\n", label);
iter->current = start;
return NULL;
return iter->current;
}
rule = (struct udev_rule *) (rules->buf + iter->current);
rule = (struct udev_rule *) (rules->buf + current);
if (strcmp(&rule->buf[rule->label.val_off], label) != 0) {
dbg(rules->udev, "moving forward, looking for label '%s'\n", label);
iter->current += sizeof(struct udev_rule) + rule->bufsize;
current += sizeof(struct udev_rule) + rule->bufsize;
goto next;
}
dbg(rules->udev, "found label '%s'\n", label);
return rule;
return current;
}
static int get_key(struct udev_rules *rules, char **line, char **key, enum key_operation *operation, char **value)
@ -674,6 +685,11 @@ static int parse_file(struct udev_rules *rules, const char *filename)
size_t cur;
size_t count;
int retval = 0;
size_t start;
struct udev_rule *rule;
struct udev_rules_iter iter;
start = rules->bufsize;
if (file_map(filename, &buf, &bufsize) != 0) {
err(rules->udev, "can't open '%s' as rules file: %s\n", filename, strerror(errno));
@ -722,6 +738,22 @@ static int parse_file(struct udev_rules *rules, const char *filename)
add_to_rules(rules, line, filename, lineno);
}
/* Compute all goto targets within this file */
udev_rules_iter_init(&iter, rules);
udev_rules_iter_goto(&iter, start);
while((rule = udev_rules_iter_next(&iter))) {
if (rule->goto_label.operation != KEY_OP_UNSET) {
char *goto_label = &rule->buf[rule->goto_label.val_off];
dbg(rules->udev, "resolving goto label '%s'", goto_label);
rule->goto_rule_off = find_label(&iter, goto_label);
if (rule->goto_rule_off == iter.current) {
err(rules->udev, "goto nonexistent label '%s' in '%s'",
goto_label, filename);
}
}
}
file_unmap(buf, bufsize);
return retval;
}