Merge tag 'printk-for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

Pull printk updates from Petr Mladek:
 "The big new thing is the fully lockless ringbuffer implementation,
  including the support for continuous lines. It will allow to store and
  read messages in any situation wihtout the risk of deadlocks and
  without the need of temporary per-CPU buffers.

  The access is still serialized by logbuf_lock. It synchronizes few
  more operations, for example, temporary buffer for formatting the
  message, syslog and kmsg_dump operations. The lock removal is being
  discussed and should be ready for the next release.

  The continuous lines are handled exactly the same way as before to
  avoid regressions in user space. It means that they are appended to
  the last message when the caller is the same. Only the last message
  can be extended.

  The data ring includes plain text of the messages. Except for an
  integer at the beginning of each message that points back to the
  descriptor ring with other metadata.

  The dictionary has to stay. journalctl uses it to filter the log. It
  allows to show messages related to a given device. The dictionary
  values are stored in the descriptor ring with the other metadata.

  This is the first part of the printk rework as discussed at Plumbers
  2019, see https://lore.kernel.org/r/87k1acz5rx.fsf@linutronix.de. The
  next big step will be handling consoles by kthreads during the normal
  system operation. It will require special handling of situations when
  the kthreads could not get scheduled, for example, early boot,
  suspend, panic.

  Other changes:

   - Add John Ogness as a reviewer for printk subsystem. He is author of
     the rework and is familiar with the code and history.

   - Fix locking in serial8250_do_startup() to prevent lockdep report.

   - Few code cleanups"

* tag 'printk-for-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (27 commits)
  printk: Use fallthrough pseudo-keyword
  printk: reduce setup_text_buf size to LOG_LINE_MAX
  printk: avoid and/or handle record truncation
  printk: remove dict ring
  printk: move dictionary keys to dev_printk_info
  printk: move printk_info into separate array
  printk: reimplement log_cont using record extension
  printk: ringbuffer: add finalization/extension support
  printk: ringbuffer: change representation of states
  printk: ringbuffer: clear initial reserved fields
  printk: ringbuffer: add BLK_DATALESS() macro
  printk: ringbuffer: relocate get_data()
  printk: ringbuffer: avoid memcpy() on state_var
  printk: ringbuffer: fix setting state in desc_read()
  kernel.h: Move oops_in_progress to printk.h
  scripts/gdb: update for lockless printk ringbuffer
  scripts/gdb: add utils.read_ulong()
  docs: vmcoreinfo: add lockless printk ringbuffer vmcoreinfo
  printk: reduce LOG_BUF_SHIFT range for H8300
  printk: ringbuffer: support dataless records
  ...

5 files changed, 18 insertions, 4 deletions

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 6594dbc34a37..206bde8308b2 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -55,6 +55,9 @@ phys_addr_t paddr_vmcoreinfo_note(void);
 #define VMCOREINFO_OFFSET(name, field) \
 	vmcoreinfo_append_str("OFFSET(%s.%s)=%lu\n", #name, #field, \
 			      (unsigned long)offsetof(struct name, field))
+#define VMCOREINFO_TYPE_OFFSET(name, field) \
+	vmcoreinfo_append_str("OFFSET(%s.%s)=%lu\n", #name, #field, \
+			      (unsigned long)offsetof(name, field))
 #define VMCOREINFO_LENGTH(name, value) \
 	vmcoreinfo_append_str("LENGTH(%s)=%lu\n", #name, (unsigned long)value)
 #define VMCOREINFO_NUMBER(name) \
diff --git a/include/linux/debug_locks.h b/include/linux/debug_locks.h
index e7e45f0cc7da..2915f56ad421 100644
--- a/include/linux/debug_locks.h
+++ b/include/linux/debug_locks.h
@@ -2,9 +2,9 @@
 #ifndef __LINUX_DEBUG_LOCKING_H
 #define __LINUX_DEBUG_LOCKING_H
 
-#include <linux/kernel.h>
 #include <linux/atomic.h>
 #include <linux/bug.h>
+#include <linux/printk.h>
 
 struct task_struct;
 
diff --git a/include/linux/dev_printk.h b/include/linux/dev_printk.h
index 3028b644b4fb..6f009559ee54 100644
--- a/include/linux/dev_printk.h
+++ b/include/linux/dev_printk.h
@@ -21,6 +21,14 @@
 
 struct device;
 
+#define PRINTK_INFO_SUBSYSTEM_LEN	16
+#define PRINTK_INFO_DEVICE_LEN		48
+
+struct dev_printk_info {
+	char subsystem[PRINTK_INFO_SUBSYSTEM_LEN];
+	char device[PRINTK_INFO_DEVICE_LEN];
+};
+
 #ifdef CONFIG_PRINTK
 
 __printf(3, 0) __cold
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index c25b8e41c0ea..e4aa29b1ad62 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -526,7 +526,6 @@ extern unsigned int sysctl_oops_all_cpu_backtrace;
 #endif /* CONFIG_SMP */
 
 extern void bust_spinlocks(int yes);
-extern int oops_in_progress;		/* If set, an oops, panic(), BUG() or die() is in progress */
 extern int panic_timeout;
 extern unsigned long panic_print;
 extern int panic_on_oops;
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 34c1a7be3e01..78479633ccfc 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -12,6 +12,8 @@
 extern const char linux_banner[];
 extern const char linux_proc_banner[];
 
+extern int oops_in_progress;	/* If set, an oops, panic(), BUG() or die() is in progress */
+
 #define PRINTK_MAX_SINGLE_HEADER_LEN 2
 
 static inline int printk_get_level(const char *buffer)
@@ -159,10 +161,12 @@ static inline void printk_nmi_direct_enter(void) { }
 static inline void printk_nmi_direct_exit(void) { }
 #endif /* PRINTK_NMI */
 
+struct dev_printk_info;
+
 #ifdef CONFIG_PRINTK
-asmlinkage __printf(5, 0)
+asmlinkage __printf(4, 0)
 int vprintk_emit(int facility, int level,
-		 const char *dict, size_t dictlen,
+		 const struct dev_printk_info *dev_info,
 		 const char *fmt, va_list args);
 
 asmlinkage __printf(1, 0)