[PATCH v13 3/9] ref_tracker: have callers pass output function to pr_ostream()

[Jeff Layton]

In a later patch, we'll be adding a 3rd mechanism for outputting
ref_tracker info via seq_file. Instead of a conditional, have the caller
set a pointer to an output function in struct ostream. As part of this,
the log prefix must be explicitly passed in, as it's too late for the
pr_fmt macro.

Reviewed-by: Andrew Lunn <and...@lunn.ch>
Signed-off-by: Jeff Layton <jlay...@kernel.org>
---
 include/linux/ref_tracker.h |  2 ++
 lib/ref_tracker.c           | 52 ++++++++++++++++++++++++++++++++-------------
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 
8eac4f3d52547ccbaf9dcd09962ce80d26fbdff8..a0a1ee43724ffa00e60c116be18e481bfe1d1455
 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -6,6 +6,8 @@
 #include <linux/spinlock.h>
 #include <linux/stackdepot.h>
 
+#define __ostream_printf __printf(2, 3)
+
 struct ref_tracker;
 
 struct ref_tracker_dir {
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 
d374e5273e1497cac0d70c02c282baa2c3ab63fe..42872f406b2a91b5bc611405cae7ce883fd8ed22
 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -63,21 +63,38 @@ ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned 
int limit)
 }
 
 struct ostream {
+       void __ostream_printf (*func)(struct ostream *stream, char *fmt, ...);
+       char *prefix;
        char *buf;
        int size, used;
 };
 
+static void __ostream_printf pr_ostream_log(struct ostream *stream, char *fmt, 
...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       vprintk(fmt, args);
+       va_end(args);
+}
+
+static void __ostream_printf pr_ostream_buf(struct ostream *stream, char *fmt, 
...)
+{
+       int ret, len = stream->size - stream->used;
+       va_list args;
+
+       va_start(args, fmt);
+       ret = vsnprintf(stream->buf + stream->used, len, fmt, args);
+       va_end(args);
+       if (ret > 0)
+               stream->used += min(ret, len);
+}
+
 #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); \
-       } \
+       _s->func(_s, fmt, ##args); \
 })
 
 static void
@@ -96,8 +113,8 @@ __ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
 
        stats = ref_tracker_get_stats(dir, display_limit);
        if (IS_ERR(stats)) {
-               pr_ostream(s, "%s@%p: couldn't get stats, error %pe\n",
-                          dir->name, dir, stats);
+               pr_ostream(s, "%s%s@%p: couldn't get stats, error %pe\n",
+                          s->prefix, dir->name, dir, stats);
                return;
        }
 
@@ -107,14 +124,15 @@ __ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
                stack = stats->stacks[i].stack_handle;
                if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 
4))
                        sbuf[0] = 0;
-               pr_ostream(s, "%s@%p has %d/%d users at\n%s\n", dir->name, dir,
-                          stats->stacks[i].count, stats->total, sbuf);
+               pr_ostream(s, "%s%s@%p has %d/%d users at\n%s\n", s->prefix,
+                          dir->name, dir, stats->stacks[i].count,
+                          stats->total, sbuf);
                skipped -= stats->stacks[i].count;
        }
 
        if (skipped)
-               pr_ostream(s, "%s@%p skipped reports about %d/%d users.\n",
-                          dir->name, dir, skipped, stats->total);
+               pr_ostream(s, "%s%s@%p skipped reports about %d/%d users.\n",
+                          s->prefix, dir->name, dir, skipped, stats->total);
 
        kfree(sbuf);
 
@@ -124,7 +142,8 @@ __ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
 void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
                                  unsigned int display_limit)
 {
-       struct ostream os = {};
+       struct ostream os = { .func = pr_ostream_log,
+                             .prefix = "ref_tracker: " };
 
        __ref_tracker_dir_pr_ostream(dir, display_limit, &os);
 }
@@ -143,7 +162,10 @@ 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 };
+       struct ostream os = { .func = pr_ostream_buf,
+                             .prefix = "ref_tracker: ",
+                             .buf = buf,
+                             .size = size };
        unsigned long flags;
 
        spin_lock_irqsave(&dir->lock, flags);

-- 
2.49.0