[PATCH v6 05/10] ref_tracker: allow pr_ostream() to print directly to a seq_file

[Jeff Layton]

Allow pr_ostream to also output directly to a seq_file without an
intermediate buffer. The first caller of +ref_tracker_dir_seq_print()
will come in a later patch, so mark that __maybe_unused for now. That
designation will be removed once it is used.

Reviewed-by: Andrew Lunn <and...@lunn.ch>
Signed-off-by: Jeff Layton <jlay...@kernel.org>
---
 lib/ref_tracker.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 
b6e0a87dd75eddef4d504419c0cf398ea65c19d8..b69c11e83c18c19aaa2dc23f802291d4a7e82a66
 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -8,6 +8,7 @@
 #include <linux/slab.h>
 #include <linux/stacktrace.h>
 #include <linux/stackdepot.h>
+#include <linux/seq_file.h>
 
 #define REF_TRACKER_STACK_ENTRIES 16
 #define STACK_BUF_SIZE 1024
@@ -70,6 +71,7 @@ struct ostream {
        void __ostream_printf (*func)(struct ostream *stream, char *fmt, ...);
        char *prefix;
        char *buf;
+       struct seq_file *seq;
        int size, used;
 };
 
@@ -93,6 +95,15 @@ static void __ostream_printf pr_ostream_buf(struct ostream 
*stream, char *fmt, .
        stream->used += min(ret, len);
 }
 
+static void __ostream_printf pr_ostream_seq(struct ostream *stream, char *fmt, 
...)
+{
+       va_list args;
+
+       va_start(args, fmt);
+       seq_vprintf(stream->seq, fmt, args);
+       va_end(args);
+}
+
 #define pr_ostream(stream, fmt, args...) \
 ({ \
        struct ostream *_s = (stream); \
@@ -302,6 +313,21 @@ EXPORT_SYMBOL_GPL(ref_tracker_free);
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 
+static __maybe_unused int
+ref_tracker_dir_seq_print(struct ref_tracker_dir *dir, struct seq_file *seq)
+{
+       struct ostream os = { .func = pr_ostream_seq,
+                             .prefix = "",
+                             .seq = seq };
+       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;
+}
+
 static int __init ref_tracker_debugfs_init(void)
 {
        ref_tracker_debug_dir = debugfs_create_dir("ref_tracker", NULL);

-- 
2.49.0