kmsg - kmsg_dump() use iterator to receive log buffer content

Provide an iterator to receive the log buffer content, and convert all
kmsg_dump() users to it.

The structured data in the kmsg buffer now contains binary data, which
should no longer be copied verbatim to the kmsg_dump() users.

The iterator should provide reliable access to the buffer data, and also
supports proper log line-aware chunking of data while iterating.

Signed-off-by: Kay Sievers <kay@vrfy.org>
Tested-by: Tony Luck <tony.luck@intel.com>
Reported-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Tested-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 38 insertions, 7 deletions

diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
index 35f7237ec97..af4eb5a39d9 100644
--- a/include/linux/kmsg_dump.h
+++ b/include/linux/kmsg_dump.h
@@ -21,6 +21,7 @@
  * is passed to the kernel.
  */
 enum kmsg_dump_reason {
+	KMSG_DUMP_UNDEF,
 	KMSG_DUMP_PANIC,
 	KMSG_DUMP_OOPS,
 	KMSG_DUMP_EMERG,
@@ -31,23 +32,37 @@ enum kmsg_dump_reason {
 
 /**
  * struct kmsg_dumper - kernel crash message dumper structure
- * @dump:	The callback which gets called on crashes. The buffer is passed
- * 		as two sections, where s1 (length l1) contains the older
- * 		messages and s2 (length l2) contains the newer.
  * @list:	Entry in the dumper list (private)
+ * @dump:	Call into dumping code which will retrieve the data with
+ * 		through the record iterator
+ * @max_reason:	filter for highest reason number that should be dumped
  * @registered:	Flag that specifies if this is already registered
  */
 struct kmsg_dumper {
-	void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason,
-			const char *s1, unsigned long l1,
-			const char *s2, unsigned long l2);
 	struct list_head list;
-	int registered;
+	void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
+	enum kmsg_dump_reason max_reason;
+	bool active;
+	bool registered;
+
+	/* private state of the kmsg iterator */
+	u32 cur_idx;
+	u32 next_idx;
+	u64 cur_seq;
+	u64 next_seq;
 };
 
 #ifdef CONFIG_PRINTK
 void kmsg_dump(enum kmsg_dump_reason reason);
 
+bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+			char *line, size_t size, size_t *len);
+
+bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+			  char *buf, size_t size, size_t *len);
+
+void kmsg_dump_rewind(struct kmsg_dumper *dumper);
+
 int kmsg_dump_register(struct kmsg_dumper *dumper);
 
 int kmsg_dump_unregister(struct kmsg_dumper *dumper);
@@ -56,6 +71,22 @@ static inline void kmsg_dump(enum kmsg_dump_reason reason)
 {
 }
 
+bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog,
+			  const char *line, size_t size, size_t *len)
+{
+	return false;
+}
+
+bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
+			    char *buf, size_t size, size_t *len)
+{
+	return false;
+}
+
+void kmsg_dump_rewind(struct kmsg_dumper *dumper)
+{
+}
+
 static inline int kmsg_dump_register(struct kmsg_dumper *dumper)
 {
 	return -EINVAL;