From 44b073b7ec467aee0d7de381d455b8ace1199184 Mon Sep 17 00:00:00 2001

From: John Ogness <john.ogness@linutronix.de>

Date: Wed, 25 Nov 2020 10:10:31 +0106

Subject: [PATCH 2/2] [PATCH 2/2] printk: use committed/finalized state values

* Required for kernel 5.10

The ringbuffer entries use 2 state values (committed and finalized)

rather than a single flag to represent being available for reading.

Copy the definitions and state lookup function directly from the

kernel source and use the new states.

Signed-off-by: John Ogness <john.ogness@linutronix.de>

---

 printk.c | 48 +++++++++++++++++++++++++++++++++++++++++-------

 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/makedumpfile-1.6.8/printk.c b/makedumpfile-1.6.8/printk.c

index acffb6c..2af8562 100644

--- a/makedumpfile-1.6.8/printk.c

+++ b/makedumpfile-1.6.8/printk.c

@@ -1,12 +1,6 @@

 #include "makedumpfile.h"

 #include <ctype.h>

-#define DESC_SV_BITS		(sizeof(unsigned long) * 8)

-#define DESC_COMMITTED_MASK	(1UL << (DESC_SV_BITS - 1))

-#define DESC_REUSE_MASK		(1UL << (DESC_SV_BITS - 2))

-#define DESC_FLAGS_MASK		(DESC_COMMITTED_MASK | DESC_REUSE_MASK)

-#define DESC_ID_MASK		(~DESC_FLAGS_MASK)

-

 /* convenience struct for passing many values to helper functions */

 struct prb_map {

 	char		*prb;

@@ -21,12 +15,51 @@ struct prb_map {

 	char		*text_data;

 };

+/*

+ * desc_state and DESC_* definitions taken from kernel source:

+ *

+ * kernel/printk/printk_ringbuffer.h

+ */

+

+/* The possible responses of a descriptor state-query. */

+enum desc_state {

+	desc_miss	=  -1,	/* ID mismatch (pseudo state) */

+	desc_reserved	= 0x0,	/* reserved, in use by writer */

+	desc_committed	= 0x1,	/* committed by writer, could get reopened */

+	desc_finalized	= 0x2,	/* committed, no further modification allowed */

+	desc_reusable	= 0x3,	/* free, not yet used by any writer */

+};

+

+#define DESC_SV_BITS		(sizeof(unsigned long) * 8)

+#define DESC_FLAGS_SHIFT	(DESC_SV_BITS - 2)

+#define DESC_FLAGS_MASK		(3UL << DESC_FLAGS_SHIFT)

+#define DESC_STATE(sv)		(3UL & (sv >> DESC_FLAGS_SHIFT))

+#define DESC_ID_MASK		(~DESC_FLAGS_MASK)

+#define DESC_ID(sv)		((sv) & DESC_ID_MASK)

+

+/*

+ * get_desc_state() taken from kernel source:

+ *

+ * kernel/printk/printk_ringbuffer.c

+ */

+

+/* Query the state of a descriptor. */

+static enum desc_state get_desc_state(unsigned long id,

+				      unsigned long state_val)

+{

+	if (id != DESC_ID(state_val))

+		return desc_miss;

+

+	return DESC_STATE(state_val);

+}

+

 static void

 dump_record(struct prb_map *m, unsigned long id)

 {

 	unsigned long long ts_nsec;

 	unsigned long state_var;

 	unsigned short text_len;

+	enum desc_state state;

 	unsigned long begin;

 	unsigned long next;

 	char buf[BUFSIZE];

@@ -45,7 +78,8 @@ dump_record(struct prb_map *m, unsigned long id)

 	/* skip non-committed record */

 	state_var = ULONG(desc + OFFSET(prb_desc.state_var) + OFFSET(atomic_long_t.counter));

-	if ((state_var & DESC_FLAGS_MASK) != DESC_COMMITTED_MASK)

+	state = get_desc_state(id, state_var);

+	if (state != desc_committed && state != desc_finalized)

 		return;

 	begin = ULONG(desc + OFFSET(prb_desc.text_blk_lpos) + OFFSET(prb_data_blk_lpos.begin)) %

-- 

2.29.2