[PATCH v3 10/10] FIT: add support to cache opened fit images

[Marco Felsch]

Cache the FIT image fit_open() calls to avoid loading the same FIT image
twice. This is very useful if the same FIT image is used to provide the
base devicetree, kernel and initrd as well as devicetree overlays.

Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
---
 common/image-fit.c  | 32 ++++++++++++++++++++++++++++++++
 include/image-fit.h |  4 ++++
 2 files changed, 36 insertions(+)

diff --git a/common/image-fit.c b/common/image-fit.c
index 4839d8dd33a4..a75bb79d1761 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -16,6 +16,7 @@
 #include <fs.h>
 #include <malloc.h>
 #include <linux/ctype.h>
+#include <linux/refcount.h>
 #include <asm/byteorder.h>
 #include <errno.h>
 #include <linux/err.h>
@@ -32,6 +33,8 @@
 #define CHECK_LEVEL_SIG 2
 #define CHECK_LEVEL_MAX 3
 
+static LIST_HEAD(open_fits);
+
 static uint32_t dt_struct_advance(struct fdt_header *f, uint32_t dt, int size)
 {
 	dt += size;
@@ -847,6 +850,18 @@ void *fit_open_configuration(struct fit_handle *handle, const char *name,
 	return conf_node;
 }
 
+static struct fit_handle *fit_get_handle(const char *filename)
+{
+	struct fit_handle *handle;
+
+	list_for_each_entry(handle, &open_fits, entry) {
+		if (!strcmp(filename, handle->filename))
+			return handle;
+	}
+
+	return NULL;
+}
+
 static int fit_do_open(struct fit_handle *handle)
 {
 	const char *desc = "(no description)";
@@ -896,6 +911,8 @@ struct fit_handle *fit_open_buf(const void *buf, size_t size, bool verbose,
 	handle->size = size;
 	handle->verify = verify;
 
+	refcount_set(&handle->users, 1);
+
 	ret = fit_do_open(handle);
 	if (ret) {
 		fit_close(handle);
@@ -923,6 +940,12 @@ struct fit_handle *fit_open(const char *filename, bool verbose,
 	struct fit_handle *handle;
 	int ret;
 
+	handle = fit_get_handle(filename);
+	if (handle) {
+		refcount_inc(&handle->users);
+		return handle;
+	}
+
 	handle = xzalloc(sizeof(struct fit_handle));
 
 	handle->verbose = verbose;
@@ -939,6 +962,9 @@ struct fit_handle *fit_open(const char *filename, bool verbose,
 	handle->fit = handle->fit_alloc;
 	handle->filename = xstrdup(filename);
 
+	refcount_set(&handle->users, 1);
+	list_add(&handle->entry, &open_fits);
+
 	ret = fit_do_open(handle);
 	if (ret) {
 		fit_close(handle);
@@ -950,9 +976,15 @@ struct fit_handle *fit_open(const char *filename, bool verbose,
 
 void fit_close(struct fit_handle *handle)
 {
+	if (!refcount_dec_and_test(&handle->users))
+		return;
+
 	if (handle->root)
 		of_delete_node(handle->root);
 
+	if (handle->filename)
+		list_del(&handle->entry);
+
 	free(handle->filename);
 	free(handle->fit_alloc);
 	free(handle);
diff --git a/include/image-fit.h b/include/image-fit.h
index 68f70f4365cb..f9791ff251c5 100644
--- a/include/image-fit.h
+++ b/include/image-fit.h
@@ -7,6 +7,7 @@
 #define __IMAGE_FIT_H__
 
 #include <linux/types.h>
+#include <linux/refcount.h>
 #include <bootm.h>
 
 struct fit_handle {
@@ -15,6 +16,9 @@ struct fit_handle {
 	size_t size;
 	char *filename;
 
+	struct list_head entry;
+	refcount_t users;
+
 	bool verbose;
 	enum bootm_verify verify;
 

-- 
2.39.2