Merge branch 'rework/nbcon-in-kdb' into for-linus (2d786a5b) · Commits · git / linux-net

arch/um/kernel/kmsg_dump.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -31,7 +31,7 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
		* expected to output the crash information.
		*/
		if (strcmp(con->name, "ttynull") != 0 &&
		(console_srcu_read_flags(con) & CON_ENABLED)) {
		console_is_usable(con, console_srcu_read_flags(con), true)) {
		break;
		}
		}

drivers/tty/serial/kgdboc.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -577,7 +577,6 @@ static int __init kgdboc_earlycon_init(char *opt)
		console_list_lock();
		for_each_console(con) {
		if (con->write && con->read &&
		(con->flags & (CON_BOOT \| CON_ENABLED)) &&
		(!opt \|\| !opt[0] \|\| strcmp(con->name, opt) == 0))
		break;
		}

include/linux/console.h

+55 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@
		#include <linux/irq_work.h>
		#include <linux/rculist.h>
		#include <linux/rcuwait.h>
		#include <linux/smp.h>
		#include <linux/types.h>
		#include <linux/vesa.h>

		@@ -602,16 +603,70 @@ static inline bool console_is_registered(const struct console *con)
		extern void nbcon_cpu_emergency_enter(void);
		extern void nbcon_cpu_emergency_exit(void);
		extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
		extern void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
		char *buf, unsigned int len);
		extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt);
		extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt);
		extern void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt);
		extern bool nbcon_kdb_try_acquire(struct console *con,
		struct nbcon_write_context *wctxt);
		extern void nbcon_kdb_release(struct nbcon_write_context *wctxt);

		/*
		* Check if the given console is currently capable and allowed to print
		* records. Note that this function does not consider the current context,
		* which can also play a role in deciding if @con can be used to print
		* records.
		*/
		static inline bool console_is_usable(struct console *con, short flags, bool use_atomic)
		{
		if (!(flags & CON_ENABLED))
		return false;

		if ((flags & CON_SUSPENDED))
		return false;

		if (flags & CON_NBCON) {
		/* The write_atomic() callback is optional. */
		if (use_atomic && !con->write_atomic)
		return false;

		/*
		* For the !use_atomic case, @printk_kthreads_running is not
		* checked because the write_thread() callback is also used
		* via the legacy loop when the printer threads are not
		* available.
		*/
		} else {
		if (!con->write)
		return false;
		}

		/*
		* Console drivers may assume that per-cpu resources have been
		* allocated. So unless they're explicitly marked as being able to
		* cope (CON_ANYTIME) don't call them until this CPU is officially up.
		*/
		if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
		return false;

		return true;
		}

		#else
		static inline void nbcon_cpu_emergency_enter(void) { }
		static inline void nbcon_cpu_emergency_exit(void) { }
		static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; }
		static inline void nbcon_write_context_set_buf(struct nbcon_write_context *wctxt,
		char *buf, unsigned int len) { }
		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; }
		static inline void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt) { }
		static inline bool nbcon_kdb_try_acquire(struct console *con,
		struct nbcon_write_context *wctxt) { return false; }
		static inline void nbcon_kdb_release(struct nbcon_write_context *wctxt) { }
		static inline bool console_is_usable(struct console *con, short flags,
		bool use_atomic) { return false; }
		#endif

		extern int console_set_on_cmdline;

include/linux/kdb.h

+16 −0

Original line number	Diff line number	Diff line
		@@ -14,6 +14,7 @@
		*/

		#include <linux/list.h>
		#include <linux/smp.h>

		/* Shifted versions of the command enable bits are be used if the command
		* has no arguments (see kdb_check_flags). This allows commands, such as
		@@ -207,11 +208,26 @@ static inline const char kdb_walk_kallsyms(loff_t pos)
		/* Dynamic kdb shell command registration */
		extern int kdb_register(kdbtab_t *cmd);
		extern void kdb_unregister(kdbtab_t *cmd);

		/* Return true when KDB as locked for printing a message on this CPU. */
		static inline
		bool kdb_printf_on_this_cpu(void)
		{
		/*
		* We can use raw_smp_processor_id() here because the task could
		* not get migrated when KDB has locked for printing on this CPU.
		*/
		return unlikely(READ_ONCE(kdb_printf_cpu) == raw_smp_processor_id());
		}

		#else /* ! CONFIG_KGDB_KDB */
		static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
		static inline void kdb_init(int level) {}
		static inline int kdb_register(kdbtab_t *cmd) { return 0; }
		static inline void kdb_unregister(kdbtab_t *cmd) {}

		static inline bool kdb_printf_on_this_cpu(void) { return false; }

		#endif /* CONFIG_KGDB_KDB */
		enum {
		KDB_NOT_INITIALIZED,

kernel/debug/kdb/kdb_io.c

+32 −15

Original line number	Diff line number	Diff line
		@@ -589,12 +589,28 @@ static void kdb_msg_write(const char *msg, int msg_len)
		*/
		cookie = console_srcu_read_lock();
		for_each_console_srcu(c) {
		if (!(console_srcu_read_flags(c) & CON_ENABLED))
		short flags = console_srcu_read_flags(c);

		if (!console_is_usable(c, flags, true))
		continue;
		if (c == dbg_io_ops->cons)
		continue;
		if (!c->write)

		if (flags & CON_NBCON) {
		struct nbcon_write_context wctxt = { };

		/*
		* Do not continue if the console is NBCON and the context
		* can't be acquired.
		*/
		if (!nbcon_kdb_try_acquire(c, &wctxt))
		continue;

		nbcon_write_context_set_buf(&wctxt, (char *)msg, msg_len);

		c->write_atomic(c, &wctxt);
		nbcon_kdb_release(&wctxt);
		} else {
		/*
		* Set oops_in_progress to encourage the console drivers to
		* disregard their internal spin locks: in the current calling
		@@ -607,6 +623,7 @@ static void kdb_msg_write(const char *msg, int msg_len)
		++oops_in_progress;
		c->write(c, msg, msg_len);
		--oops_in_progress;
		}
		touch_nmi_watchdog();
		}
		console_srcu_read_unlock(cookie);