[PATCH 4/9] lib/ref_tracker: add printing to memory buffer

Andrzej Hajda
2022-02-17T14:05:28Z

In case one wants to show stats via debugfs.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Chris Wilson <chris.p.wilson@intel.com>
---
include/linux/ref_tracker.h | 8 ++++++
lib/ref_tracker.c | 52 ++++++++++++++++++++++++++++++++-----
2 files changed, 54 insertions(+), 6 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 090230e5b485d..6d2634590ee5a 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -46,6 +46,8 @@ void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
void ref_tracker_dir_print(struct ref_tracker_dir *dir,
unsigned int display_limit);

+int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size);
+
int ref_tracker_alloc(struct ref_tracker_dir *dir,
struct ref_tracker **trackerp, gfp_t gfp);

@@ -74,6 +76,12 @@ static inline void ref_tracker_dir_print(struct ref_tracker_dir *dir,
{
}

+static inline int ref_tracker_dir_snprint(struct ref_tracker_dir *dir,
+ char *buf, size_t size)
+{
+ return 0;
+}
+
static inline int ref_tracker_alloc(struct ref_tracker_dir *dir,
struct ref_tracker **trackerp,
gfp_t gfp)
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 943cff08110e3..7b00bca300043 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -27,8 +27,27 @@ static int ref_tracker_cmp(void *priv, const struct list_head *a, const struct l
return ta->alloc_stack_handle - tb->alloc_stack_handle;
}

-void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
- unsigned int display_limit)
+struct ostream {
+ char *buf;
+ int size, used;
+};
+
+#define pr_ostream(stream, fmt, args...) \
+({ \
+ struct ostream *_s = (stream); \
+\
+ if (!_s->buf) { \
+ pr_err(fmt, ##args); \
+ } else { \
+ int ret, len = _s->size - _s->used; \
+ ret = snprintf(_s->buf + _s->used, len, pr_fmt(fmt), ##args); \
+ _s->used += min(ret, len); \
+ } \
+})
+
+static void
+__ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
+ unsigned int display_limit, struct ostream *s)
{
unsigned int i = 0, count = 0, total = 0;
struct ref_tracker *tracker;
@@ -58,16 +77,24 @@ void __ref_tracker_dir_print(struct ref_tracker_dir *dir,

if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
sbuf[0] = 0;
- pr_err("%s@%pK has %d/%d users at\n%s\n",
- dir->name, dir, count, total, sbuf);
+ pr_ostream(s, "%s@%pK has %d/%d users at\n%s\n",
+ dir->name, dir, count, total, sbuf);
count = 0;
}
if (i > display_limit)
- pr_err("%s@%pK skipped %d/%d reports with %d unique stacks.\n",
- dir->name, dir, count, total, i - display_limit);
+ pr_ostream(s, "%s@%pK skipped %d/%d reports with %d unique stacks.\n",
+ dir->name, dir, count, total, i - display_limit);

kfree(sbuf);
}
+
+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+ unsigned int display_limit)
+{
+ struct ostream os = {};
+
+ __ref_tracker_dir_pr_ostream(dir, display_limit, &os);
+}
EXPORT_SYMBOL(__ref_tracker_dir_print);

void ref_tracker_dir_print(struct ref_tracker_dir *dir,
@@ -81,6 +108,19 @@ void ref_tracker_dir_print(struct ref_tracker_dir *dir,
}
EXPORT_SYMBOL(ref_tracker_dir_print);

+int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)
+{
+ struct ostream os = { .buf = buf, .size = size };
+ unsigned long flags;
+
+ spin_lock_irqsave(&dir->lock, flags);
+ __ref_tracker_dir_pr_ostream(dir, 16, &os);
+ spin_unlock_irqrestore(&dir->lock, flags);
+
+ return os.used;
+}
+EXPORT_SYMBOL(ref_tracker_dir_snprint);
+
void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
{
struct ref_tracker *tracker, *n;
--
2.25.1