extern const struct consw vga_con; /* VGA text console */
extern const struct consw newport_con; /* SGI Newport console */
+struct screen_info;
+#ifdef CONFIG_VGA_CONSOLE
+void vgacon_register_screen(struct screen_info *si);
+#else
+static inline void vgacon_register_screen(struct screen_info *si) { }
+#endif
+
int con_is_bound(const struct consw *csw);
int do_unregister_con_driver(const struct consw *csw);
int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
* /dev/kmesg which requires a larger output buffer.
* @CON_SUSPENDED: Indicates if a console is suspended. If true, the
* printing callbacks must not be called.
+ * @CON_NBCON: Console can operate outside of the legacy style console_lock
+ * constraints.
*/
enum cons_flags {
CON_PRINTBUFFER = BIT(0),
CON_BRL = BIT(5),
CON_EXTENDED = BIT(6),
CON_SUSPENDED = BIT(7),
+ CON_NBCON = BIT(8),
+};
+
+/**
+ * struct nbcon_state - console state for nbcon consoles
+ * @atom: Compound of the state fields for atomic operations
+ *
+ * @req_prio: The priority of a handover request
+ * @prio: The priority of the current owner
+ * @unsafe: Console is busy in a non takeover region
+ * @unsafe_takeover: A hostile takeover in an unsafe state happened in the
+ * past. The console cannot be safe until re-initialized.
+ * @cpu: The CPU on which the owner runs
+ *
+ * To be used for reading and preparing of the value stored in the nbcon
+ * state variable @console::nbcon_state.
+ *
+ * The @prio and @req_prio fields are particularly important to allow
+ * spin-waiting to timeout and give up without the risk of a waiter being
+ * assigned the lock after giving up.
+ */
+struct nbcon_state {
+ union {
+ unsigned int atom;
+ struct {
+ unsigned int prio : 2;
+ unsigned int req_prio : 2;
+ unsigned int unsafe : 1;
+ unsigned int unsafe_takeover : 1;
+ unsigned int cpu : 24;
+ };
+ };
+};
+
+/*
+ * The nbcon_state struct is used to easily create and interpret values that
+ * are stored in the @console::nbcon_state variable. Ensure this struct stays
+ * within the size boundaries of the atomic variable's underlying type in
+ * order to avoid any accidental truncation.
+ */
+static_assert(sizeof(struct nbcon_state) <= sizeof(int));
+
+/**
+ * nbcon_prio - console owner priority for nbcon consoles
+ * @NBCON_PRIO_NONE: Unused
+ * @NBCON_PRIO_NORMAL: Normal (non-emergency) usage
+ * @NBCON_PRIO_EMERGENCY: Emergency output (WARN/OOPS...)
+ * @NBCON_PRIO_PANIC: Panic output
+ * @NBCON_PRIO_MAX: The number of priority levels
+ *
+ * A higher priority context can takeover the console when it is
+ * in the safe state. The final attempt to flush consoles in panic()
+ * can be allowed to do so even in an unsafe state (Hope and pray).
+ */
+enum nbcon_prio {
+ NBCON_PRIO_NONE = 0,
+ NBCON_PRIO_NORMAL,
+ NBCON_PRIO_EMERGENCY,
+ NBCON_PRIO_PANIC,
+ NBCON_PRIO_MAX,
+};
+
+struct console;
+struct printk_buffers;
+
+/**
+ * struct nbcon_context - Context for console acquire/release
+ * @console: The associated console
+ * @spinwait_max_us: Limit for spin-wait acquire
+ * @prio: Priority of the context
+ * @allow_unsafe_takeover: Allow performing takeover even if unsafe. Can
+ * be used only with NBCON_PRIO_PANIC @prio. It
+ * might cause a system freeze when the console
+ * is used later.
+ * @backlog: Ringbuffer has pending records
+ * @pbufs: Pointer to the text buffer for this context
+ * @seq: The sequence number to print for this context
+ */
+struct nbcon_context {
+ /* members set by caller */
+ struct console *console;
+ unsigned int spinwait_max_us;
+ enum nbcon_prio prio;
+ unsigned int allow_unsafe_takeover : 1;
+
+ /* members set by emit */
+ unsigned int backlog : 1;
+
+ /* members set by acquire */
+ struct printk_buffers *pbufs;
+ u64 seq;
+};
+
+/**
+ * struct nbcon_write_context - Context handed to the nbcon write callbacks
+ * @ctxt: The core console context
+ * @outbuf: Pointer to the text buffer for output
+ * @len: Length to write
+ * @unsafe_takeover: If a hostile takeover in an unsafe state has occurred
+ */
+struct nbcon_write_context {
+ struct nbcon_context __private ctxt;
+ char *outbuf;
+ unsigned int len;
+ bool unsafe_takeover;
};
/**
* @dropped: Number of unreported dropped ringbuffer records
* @data: Driver private data
* @node: hlist node for the console list
+ *
+ * @write_atomic: Write callback for atomic context
+ * @nbcon_state: State for nbcon consoles
+ * @nbcon_seq: Sequence number of the next record for nbcon to print
+ * @pbufs: Pointer to nbcon private buffer
*/
struct console {
char name[16];
unsigned long dropped;
void *data;
struct hlist_node node;
+
+ /* nbcon console specific members */
+ bool (*write_atomic)(struct console *con,
+ struct nbcon_write_context *wctxt);
+ atomic_t __private nbcon_state;
+ atomic_long_t __private nbcon_seq;
+ struct printk_buffers *pbufs;
};
#ifdef CONFIG_LOCKDEP
lockdep_assert_console_list_lock_held(); \
hlist_for_each_entry(con, &console_list, node)
+#ifdef CONFIG_PRINTK
+extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
+extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt);
+extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt);
+#else
+static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; }
+static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; }
+static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; }
+#endif
+
extern int console_set_on_cmdline;
extern struct console *early_console;
CONSOLE_REPLAY_ALL,
};
-extern int add_preferred_console(char *name, int idx, char *options);
+extern int add_preferred_console(const char *name, const short idx, char *options);
extern void console_force_preferred_locked(struct console *con);
extern void register_console(struct console *);
extern int unregister_console(struct console *);
projects / linux-2.6-block.git / blobdiff