The patch titled
printk: add interfaces for external access to the log buffer
has been removed from the -mm tree. Its filename was
printk-add-interfaces-for-external-access-to-the-log-buffer.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: printk: add interfaces for external access to the log buffer
From: Mike Frysinger <vapier.adi@xxxxxxxxx>
Add two new functions for reading the kernel log buffer. The intention is for
them to be used by recovery/dump/debug code so the kernel log can be easily
retrieved/parsed in a crash scenario, but they are generic enough for other
people to dream up other fun uses.
[akpm@xxxxxxxxxxxxxxxxxxxx: buncha fixes]
Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>
Cc: Robin Getz <rgetz@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg Ungerer <gerg@xxxxxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Paul Mundt <lethal@xxxxxxxxxxxx>
Acked-by: Tim Bird <tim.bird@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kernel.h | 6 ++++
kernel/printk.c | 52 +++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff -puN include/linux/kernel.h~printk-add-interfaces-for-external-access-to-the-log-buffer include/linux/kernel.h
--- a/include/linux/kernel.h~printk-add-interfaces-for-external-access-to-the-log-buffer
+++ a/include/linux/kernel.h
@@ -172,6 +172,9 @@ asmlinkage int vprintk(const char *fmt,
__attribute__ ((format (printf, 1, 0)));
asmlinkage int printk(const char * fmt, ...)
__attribute__ ((format (printf, 1, 2))) __cold;
+extern int log_buf_get_len(void);
+extern int log_buf_read(int idx);
+extern int log_buf_copy(char *dest, int idx, int len);
#else
static inline int vprintk(const char *s, va_list args)
__attribute__ ((format (printf, 1, 0)));
@@ -179,6 +182,9 @@ static inline int vprintk(const char *s,
static inline int printk(const char *s, ...)
__attribute__ ((format (printf, 1, 2)));
static inline int __cold printk(const char *s, ...) { return 0; }
+static inline int log_buf_get_len(void) { return 0; }
+static inline int log_buf_read(int idx) { return 0; }
+static inline int log_buf_copy(char *dest, int idx, int len) { return 0; }
#endif
unsigned long int_sqrt(unsigned long);
diff -puN kernel/printk.c~printk-add-interfaces-for-external-access-to-the-log-buffer kernel/printk.c
--- a/kernel/printk.c~printk-add-interfaces-for-external-access-to-the-log-buffer
+++ a/kernel/printk.c
@@ -220,6 +220,58 @@ static inline void boot_delay_msec(void)
#endif
/*
+ * Return the number of unread characters in the log buffer.
+ */
+int log_buf_get_len(void)
+{
+ return logged_chars;
+}
+
+/*
+ * Copy a range of characters from the log buffer.
+ */
+int log_buf_copy(char *dest, int idx, int len)
+{
+ int ret, max;
+ bool took_lock = false;
+
+ if (!oops_in_progress) {
+ spin_lock_irq(&logbuf_lock);
+ took_lock = true;
+ }
+
+ max = log_buf_get_len();
+ if (idx < 0 || idx >= max) {
+ ret = -1;
+ } else {
+ if (len > max)
+ len = max;
+ ret = len;
+ idx += (log_end - max);
+ while (len-- > 0)
+ dest[len] = LOG_BUF(idx + len);
+ }
+
+ if (took_lock)
+ spin_unlock_irq(&logbuf_lock);
+
+ return ret;
+}
+
+/*
+ * Extract a single character from the log buffer.
+ */
+int log_buf_read(int idx)
+{
+ char ret;
+
+ if (log_buf_copy(&ret, idx, 1) == 1)
+ return ret;
+ else
+ return -1;
+}
+
+/*
* Commands to do_syslog:
*
* 0 -- Close the log. Currently a NOP.
_
Patches currently in -mm which might be from vapier.adi@xxxxxxxxx are
origin.patch
kernel-printkc-concerns-about-the-console-handover.patch
-
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