Merge tag 'pstore-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull pstore updates from Kees Cook:
 "This has a large internal refactoring along with several smaller
  fixes.

   - constify compression structures; Bhumika Goyal

   - restore powerpc dumping; Ankit Kumar

   - fix more bugs in the rarely exercises module unloading logic

   - reorganize filesystem locking to fix problems noticed by lockdep

   - refactor internal pstore APIs to make development and review
     easier:
      - improve error reporting
      - add kernel-doc structure and function comments
      - avoid insane argument passing by using a common record
        structure"

* tag 'pstore-v4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (23 commits)
  pstore: Solve lockdep warning by moving inode locks
  pstore: Fix flags to enable dumps on powerpc
  pstore: Remove unused vmalloc.h in pmsg
  pstore: simplify write_user_compat()
  pstore: Remove write_buf() callback
  pstore: Replace arguments for write_buf_user() API
  pstore: Replace arguments for write_buf() API
  pstore: Replace arguments for erase() API
  pstore: Do not duplicate record metadata
  pstore: Allocate records on heap instead of stack
  pstore: Pass record contents instead of copying
  pstore: Always allocate buffer for decompression
  pstore: Replace arguments for write() API
  pstore: Replace arguments for read() API
  pstore: Switch pstore_mkfile to pass record
  pstore: Move record decompression to function
  pstore: Extract common arguments into structure
  pstore: Add kernel-doc for struct pstore_info
  pstore: Improve register_pstore() error reporting
  pstore: Avoid race in module unloading
  ...

1 files changed, 131 insertions, 25 deletions

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 0da29cae009b..e2233f50f428 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -30,7 +30,9 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
-/* types */
+struct module;
+
+/* pstore record types (see fs/pstore/inode.c for filename templates) */
 enum pstore_type_id {
 	PSTORE_TYPE_DMESG	= 0,
 	PSTORE_TYPE_MCE		= 1,
@@ -45,42 +47,146 @@ enum pstore_type_id {
 	PSTORE_TYPE_UNKNOWN	= 255
 };
 
-struct module;
+struct pstore_info;
+/**
+ * struct pstore_record - details of a pstore record entry
+ * @psi:	pstore backend driver information
+ * @type:	pstore record type
+ * @id:		per-type unique identifier for record
+ * @time:	timestamp of the record
+ * @buf:	pointer to record contents
+ * @size:	size of @buf
+ * @ecc_notice_size:
+ *		ECC information for @buf
+ *
+ * Valid for PSTORE_TYPE_DMESG @type:
+ *
+ * @count:	Oops count since boot
+ * @reason:	kdump reason for notification
+ * @part:	position in a multipart record
+ * @compressed:	whether the buffer is compressed
+ *
+ */
+struct pstore_record {
+	struct pstore_info	*psi;
+	enum pstore_type_id	type;
+	u64			id;
+	struct timespec		time;
+	char			*buf;
+	ssize_t			size;
+	ssize_t			ecc_notice_size;
 
+	int			count;
+	enum kmsg_dump_reason	reason;
+	unsigned int		part;
+	bool			compressed;
+};
+
+/**
+ * struct pstore_info - backend pstore driver structure
+ *
+ * @owner:	module which is repsonsible for this backend driver
+ * @name:	name of the backend driver
+ *
+ * @buf_lock:	spinlock to serialize access to @buf
+ * @buf:	preallocated crash dump buffer
+ * @bufsize:	size of @buf available for crash dump writes
+ *
+ * @read_mutex:	serializes @open, @read, @close, and @erase callbacks
+ * @flags:	bitfield of frontends the backend can accept writes for
+ * @data:	backend-private pointer passed back during callbacks
+ *
+ * Callbacks:
+ *
+ * @open:
+ *	Notify backend that pstore is starting a full read of backend
+ *	records. Followed by one or more @read calls, and a final @close.
+ *
+ *	@psi:	in: pointer to the struct pstore_info for the backend
+ *
+ *	Returns 0 on success, and non-zero on error.
+ *
+ * @close:
+ *	Notify backend that pstore has finished a full read of backend
+ *	records. Always preceded by an @open call and one or more @read
+ *	calls.
+ *
+ *	@psi:	in: pointer to the struct pstore_info for the backend
+ *
+ *	Returns 0 on success, and non-zero on error. (Though pstore will
+ *	ignore the error.)
+ *
+ * @read:
+ *	Read next available backend record. Called after a successful
+ *	@open.
+ *
+ *	@record:
+ *		pointer to record to populate. @buf should be allocated
+ *		by the backend and filled. At least @type and @id should
+ *		be populated, since these are used when creating pstorefs
+ *		file names.
+ *
+ *	Returns record size on success, zero when no more records are
+ *	available, or negative on error.
+ *
+ * @write:
+ *	A newly generated record needs to be written to backend storage.
+ *
+ *	@record:
+ *		pointer to record metadata. When @type is PSTORE_TYPE_DMESG,
+ *		@buf will be pointing to the preallocated @psi.buf, since
+ *		memory allocation may be broken during an Oops. Regardless,
+ *		@buf must be proccesed or copied before returning. The
+ *		backend is also expected to write @id with something that
+ 8		can help identify this record to a future @erase callback.
+ *
+ *	Returns 0 on success, and non-zero on error.
+ *
+ * @write_user:
+ *	Perform a frontend write to a backend record, using a specified
+ *	buffer that is coming directly from userspace, instead of the
+ *	@record @buf.
+ *
+ *	@record:	pointer to record metadata.
+ *	@buf:		pointer to userspace contents to write to backend
+ *
+ *	Returns 0 on success, and non-zero on error.
+ *
+ * @erase:
+ *	Delete a record from backend storage.  Different backends
+ *	identify records differently, so entire original record is
+ *	passed back to assist in identification of what the backend
+ *	should remove from storage.
+ *
+ *	@record:	pointer to record metadata.
+ *
+ *	Returns 0 on success, and non-zero on error.
+ *
+ */
 struct pstore_info {
 	struct module	*owner;
 	char		*name;
-	spinlock_t	buf_lock;	/* serialize access to 'buf' */
+
+	spinlock_t	buf_lock;
 	char		*buf;
 	size_t		bufsize;
-	struct mutex	read_mutex;	/* serialize open/read/close */
+
+	struct mutex	read_mutex;
+
 	int		flags;
+	void		*data;
+
 	int		(*open)(struct pstore_info *psi);
 	int		(*close)(struct pstore_info *psi);
-	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
-			int *count, struct timespec *time, char **buf,
-			bool *compressed, ssize_t *ecc_notice_size,
-			struct pstore_info *psi);
-	int		(*write)(enum pstore_type_id type,
-			enum kmsg_dump_reason reason, u64 *id,
-			unsigned int part, int count, bool compressed,
-			size_t size, struct pstore_info *psi);
-	int		(*write_buf)(enum pstore_type_id type,
-			enum kmsg_dump_reason reason, u64 *id,
-			unsigned int part, const char *buf, bool compressed,
-			size_t size, struct pstore_info *psi);
-	int		(*write_buf_user)(enum pstore_type_id type,
-			enum kmsg_dump_reason reason, u64 *id,
-			unsigned int part, const char __user *buf,
-			bool compressed, size_t size, struct pstore_info *psi);
-	int		(*erase)(enum pstore_type_id type, u64 id,
-			int count, struct timespec time,
-			struct pstore_info *psi);
-	void		*data;
+	ssize_t		(*read)(struct pstore_record *record);
+	int		(*write)(struct pstore_record *record);
+	int		(*write_user)(struct pstore_record *record,
+				      const char __user *buf);
+	int		(*erase)(struct pstore_record *record);
 };
 
+/* Supported frontends */
 #define PSTORE_FLAGS_DMESG	(1 << 0)
-#define PSTORE_FLAGS_FRAGILE	PSTORE_FLAGS_DMESG
 #define PSTORE_FLAGS_CONSOLE	(1 << 1)
 #define PSTORE_FLAGS_FTRACE	(1 << 2)
 #define PSTORE_FLAGS_PMSG	(1 << 3)