---

yaml
---
r: 84303
b: refs/heads/master
c: 388bbb0
h: refs/heads/master
i:
  84301: 0fd8304
  84299: 540ac20
  84295: 980c885
  84287: 755c68f
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 76b104671632c225ad594a50f9e26ada67bc0a74
+refs/heads/master: 388bbb09b991c792310af2f6b49f6c55edb3dff0

trunk/drivers/mtd/mtdpart.c

@@ -151,6 +151,20 @@ static int part_write (struct mtd_info *mtd, loff_t to, size_t len,
 				    len, retlen, buf);
 }
 
+static int part_panic_write (struct mtd_info *mtd, loff_t to, size_t len,
+			size_t *retlen, const u_char *buf)
+{
+	struct mtd_part *part = PART(mtd);
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+	if (to >= mtd->size)
+		len = 0;
+	else if (to + len > mtd->size)
+		len = mtd->size - to;
+	return part->master->panic_write (part->master, to + part->offset,
+				    len, retlen, buf);
+}
+
 static int part_write_oob(struct mtd_info *mtd, loff_t to,
 			 struct mtd_oob_ops *ops)
 {
@@ -352,6 +366,9 @@ int add_mtd_partitions(struct mtd_info *master,
 		slave->mtd.read = part_read;
 		slave->mtd.write = part_write;
 
+		if (master->panic_write)
+			slave->mtd.panic_write = part_panic_write;
+
 		if(master->point && master->unpoint){
 			slave->mtd.point = part_point;
 			slave->mtd.unpoint = part_unpoint;

trunk/include/linux/mtd/mtd.h

@@ -152,6 +152,15 @@ struct mtd_info {
 	int (*read) (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf);
 	int (*write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);
 
+	/* In blackbox flight recorder like scenarios we want to make successful
+	   writes in interrupt context. panic_write() is only intended to be
+	   called when its known the kernel is about to panic and we need the
+	   write to succeed. Since the kernel is not going to be running for much
+	   longer, this function can break locks and delay to ensure the write
+	   succeeds (but not sleep). */
+
+	int (*panic_write) (struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const u_char *buf);
+
 	int (*read_oob) (struct mtd_info *mtd, loff_t from,
 			 struct mtd_oob_ops *ops);
 	int (*write_oob) (struct mtd_info *mtd, loff_t to,