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ftrace: add do_for_each_ftrace_rec and while_for_each_ftrace_rec
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Impact: clean up

To iterate over all the functions that dynamic trace knows about
it requires two for loops. One to iterate over the pages and the
other to iterate over the records within the page.

There are several duplications of these loops in ftrace.c. This
patch creates the macros do_for_each_ftrace_rec and
while_for_each_ftrace_rec to handle this logic, and removes the
duplicate code.

While making this change, I also discovered and fixed a small
bug that one of the iterations should exit the loop after it found the
record it was searching for. This used a break when it should have
used a goto, since there were two loops it needed to break out
from.  No real harm was done by this bug since it would only continue
to search the other records, and the code was in a slow path anyway.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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Steven Rostedt committed Feb 16, 2009
1 parent 0c75a3e commit 265c831
Showing 1 changed file with 101 additions and 107 deletions.
208 changes: 101 additions & 107 deletions kernel/trace/ftrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -297,6 +297,19 @@ static struct ftrace_page *ftrace_pages;

static struct dyn_ftrace *ftrace_free_records;

/*
* This is a double for. Do not use 'break' to break out of the loop,
* you must use a goto.
*/
#define do_for_each_ftrace_rec(pg, rec) \
for (pg = ftrace_pages_start; pg; pg = pg->next) { \
int _____i; \
for (_____i = 0; _____i < pg->index; _____i++) { \
rec = &pg->records[_____i];

#define while_for_each_ftrace_rec() \
} \
}

#ifdef CONFIG_KPROBES

Expand Down Expand Up @@ -341,22 +354,18 @@ void ftrace_release(void *start, unsigned long size)
struct ftrace_page *pg;
unsigned long s = (unsigned long)start;
unsigned long e = s + size;
int i;

if (ftrace_disabled || !start)
return;

/* should not be called from interrupt context */
spin_lock(&ftrace_lock);

for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
do_for_each_ftrace_rec(pg, rec) {
if ((rec->ip >= s) && (rec->ip < e))
ftrace_free_rec(rec);
} while_for_each_ftrace_rec();

if ((rec->ip >= s) && (rec->ip < e))
ftrace_free_rec(rec);
}
}
spin_unlock(&ftrace_lock);
}

Expand Down Expand Up @@ -523,41 +532,37 @@ __ftrace_replace_code(struct dyn_ftrace *rec, int enable)

static void ftrace_replace_code(int enable)
{
int i, failed;
int failed;
struct dyn_ftrace *rec;
struct ftrace_page *pg;

for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];

/*
* Skip over free records and records that have
* failed.
*/
if (rec->flags & FTRACE_FL_FREE ||
rec->flags & FTRACE_FL_FAILED)
continue;

/* ignore updates to this record's mcount site */
if (get_kprobe((void *)rec->ip)) {
freeze_record(rec);
continue;
} else {
unfreeze_record(rec);
}
do_for_each_ftrace_rec(pg, rec) {
/*
* Skip over free records and records that have
* failed.
*/
if (rec->flags & FTRACE_FL_FREE ||
rec->flags & FTRACE_FL_FAILED)
continue;

failed = __ftrace_replace_code(rec, enable);
if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
rec->flags |= FTRACE_FL_FAILED;
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(rec->ip)) {
ftrace_free_rec(rec);
} else
ftrace_bug(failed, rec->ip);
}
/* ignore updates to this record's mcount site */
if (get_kprobe((void *)rec->ip)) {
freeze_record(rec);
continue;
} else {
unfreeze_record(rec);
}
}

failed = __ftrace_replace_code(rec, enable);
if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
rec->flags |= FTRACE_FL_FAILED;
if ((system_state == SYSTEM_BOOTING) ||
!core_kernel_text(rec->ip)) {
ftrace_free_rec(rec);
} else
ftrace_bug(failed, rec->ip);
}
} while_for_each_ftrace_rec();
}

static int
Expand Down Expand Up @@ -956,22 +961,17 @@ static void ftrace_filter_reset(int enable)
struct ftrace_page *pg;
struct dyn_ftrace *rec;
unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
unsigned i;

/* should not be called from interrupt context */
spin_lock(&ftrace_lock);
if (enable)
ftrace_filtered = 0;
pg = ftrace_pages_start;
while (pg) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];
if (rec->flags & FTRACE_FL_FAILED)
continue;
rec->flags &= ~type;
}
pg = pg->next;
}
do_for_each_ftrace_rec(pg, rec) {
if (rec->flags & FTRACE_FL_FAILED)
continue;
rec->flags &= ~type;
} while_for_each_ftrace_rec();

spin_unlock(&ftrace_lock);
}

Expand Down Expand Up @@ -1094,44 +1094,39 @@ ftrace_match(unsigned char *buff, int len, int enable)
spin_lock(&ftrace_lock);
if (enable)
ftrace_filtered = 1;
pg = ftrace_pages_start;
while (pg) {
for (i = 0; i < pg->index; i++) {
int matched = 0;
char *ptr;

rec = &pg->records[i];
if (rec->flags & FTRACE_FL_FAILED)
continue;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
switch (type) {
case MATCH_FULL:
if (strcmp(str, buff) == 0)
matched = 1;
break;
case MATCH_FRONT_ONLY:
if (memcmp(str, buff, match) == 0)
matched = 1;
break;
case MATCH_MIDDLE_ONLY:
if (strstr(str, search))
matched = 1;
break;
case MATCH_END_ONLY:
ptr = strstr(str, search);
if (ptr && (ptr[search_len] == 0))
matched = 1;
break;
}
if (matched) {
if (not)
rec->flags &= ~flag;
else
rec->flags |= flag;
}
do_for_each_ftrace_rec(pg, rec) {
int matched = 0;
char *ptr;

if (rec->flags & FTRACE_FL_FAILED)
continue;
kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
switch (type) {
case MATCH_FULL:
if (strcmp(str, buff) == 0)
matched = 1;
break;
case MATCH_FRONT_ONLY:
if (memcmp(str, buff, match) == 0)
matched = 1;
break;
case MATCH_MIDDLE_ONLY:
if (strstr(str, search))
matched = 1;
break;
case MATCH_END_ONLY:
ptr = strstr(str, search);
if (ptr && (ptr[search_len] == 0))
matched = 1;
break;
}
pg = pg->next;
}
if (matched) {
if (not)
rec->flags &= ~flag;
else
rec->flags |= flag;
}
} while_for_each_ftrace_rec();
spin_unlock(&ftrace_lock);
}

Expand Down Expand Up @@ -1452,35 +1447,34 @@ ftrace_set_func(unsigned long *array, int idx, char *buffer)
struct dyn_ftrace *rec;
struct ftrace_page *pg;
int found = 0;
int i, j;
int j;

if (ftrace_disabled)
return -ENODEV;

/* should not be called from interrupt context */
spin_lock(&ftrace_lock);

for (pg = ftrace_pages_start; pg; pg = pg->next) {
for (i = 0; i < pg->index; i++) {
rec = &pg->records[i];

if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
continue;

kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
if (strcmp(str, buffer) == 0) {
found = 1;
for (j = 0; j < idx; j++)
if (array[j] == rec->ip) {
found = 0;
break;
}
if (found)
array[idx] = rec->ip;
break;
}
do_for_each_ftrace_rec(pg, rec) {

if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
continue;

kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
if (strcmp(str, buffer) == 0) {
/* Return 1 if we add it to the array */
found = 1;
for (j = 0; j < idx; j++)
if (array[j] == rec->ip) {
found = 0;
break;
}
if (found)
array[idx] = rec->ip;
goto out;
}
}
} while_for_each_ftrace_rec();
out:
spin_unlock(&ftrace_lock);

return found ? 0 : -EINVAL;
Expand Down

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