Write log messages with log_level > PR_NOTICE only to in memory log

We modify write() (adding console_write()) which calls down to
a modified __flush_console() which can now decide if it's flushing
the added console contents to the console drivers or not.

A future patch may add support for changing PR_NOTICE to some other level

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

4 files changed, 36 insertions, 15 deletions

diff --git a/core/console-log.c b/core/console-log.c
index 6a70e57..3d1b43f 100644
--- a/core/console-log.c
+++ b/core/console-log.c
@@ -24,6 +24,7 @@
 #include "skiboot.h"
 #include "unistd.h"
 #include "stdio.h"
+#include "console.h"
 #include "timebase.h"
 
 static int vprlog(int log_level, const char *fmt, va_list ap)
@@ -34,7 +35,8 @@ static int vprlog(int log_level, const char *fmt, va_list ap)
 	count = snprintf(buffer, sizeof(buffer), "[%lu,%d] ",
 			 mftb(), log_level);
 	count+= vsnprintf(buffer+count, sizeof(buffer)-count, fmt, ap);
-	write(0, buffer, count);
+
+	console_write((log_level > PR_NOTICE) ? false : true, buffer, count);
 
 	return count;
 }
diff --git a/core/console.c b/core/console.c
index 5794151..9b41962 100644
--- a/core/console.c
+++ b/core/console.c
@@ -81,9 +81,11 @@ void clear_console(void)
 
 /*
  * Flush the console buffer into the driver, returns true
- * if there is more to go
+ * if there is more to go.
+ * Optionally can skip flushing to drivers, leaving messages
+ * just in memory console.
  */
-bool __flush_console(void)
+bool __flush_console(bool flush_to_drivers)
 {
 	struct cpu_thread *cpu = this_cpu();
 	size_t req, len = 0;
@@ -124,18 +126,27 @@ bool __flush_console(void)
 		more_flush = false;
 		if (con_out > con_in) {
 			req = INMEM_CON_OUT_LEN - con_out;
-			unlock(&con_lock);
-			len = con_driver->write(con_buf + con_out, req);
-			lock(&con_lock);
+			if (!flush_to_drivers) {
+				len = req;
+			} else {
+				unlock(&con_lock);
+				len = con_driver->write(con_buf + con_out,
+							req);
+				lock(&con_lock);
+			}
 			con_out = (con_out + len) % INMEM_CON_OUT_LEN;
 			if (len < req)
 				goto bail;
 		}
 		if (con_out < con_in) {
-			unlock(&con_lock);
-			len = con_driver->write(con_buf + con_out,
-						con_in - con_out);
-			lock(&con_lock);
+			if (!flush_to_drivers) {
+				len = con_in - con_out;
+			} else {
+				unlock(&con_lock);
+				len = con_driver->write(con_buf + con_out,
+							con_in - con_out);
+				lock(&con_lock);
+			}
 			con_out = (con_out + len) % INMEM_CON_OUT_LEN;
 		}
 	} while(more_flush);
@@ -149,7 +160,7 @@ bool flush_console(void)
 	bool ret;
 
 	lock(&con_lock);
-	ret = __flush_console();
+	ret = __flush_console(true);
 	unlock(&con_lock);
 
 	return ret;
@@ -206,7 +217,7 @@ static void write_char(char c)
 	inmem_write(c);
 }
 
-ssize_t write(int fd __unused, const void *buf, size_t count)
+ssize_t console_write(bool flush_to_drivers, const void *buf, size_t count)
 {
 	/* We use recursive locking here as we can get called
 	 * from fairly deep debug path
@@ -221,7 +232,7 @@ ssize_t write(int fd __unused, const void *buf, size_t count)
 		write_char(c);
 	}
 
-	__flush_console();
+	__flush_console(flush_to_drivers);
 
 	if (need_unlock)
 		unlock(&con_lock);
@@ -229,6 +240,11 @@ ssize_t write(int fd __unused, const void *buf, size_t count)
 	return count;
 }
 
+ssize_t write(int fd __unused, const void *buf, size_t count)
+{
+	return console_write(true, buf, count);
+}
+
 ssize_t read(int fd __unused, void *buf, size_t req_count)
 {
 	bool need_unlock = lock_recursive(&con_lock);
diff --git a/hw/fsp/fsp-console.c b/hw/fsp/fsp-console.c
index 858f56a..d14e520 100644
--- a/hw/fsp/fsp-console.c
+++ b/hw/fsp/fsp-console.c
@@ -667,7 +667,7 @@ void fsp_console_poll(void *data __unused)
 			if (sb->next_out == sb->next_in)
 				continue;
 			if (fs->log_port)
-				__flush_console();
+				__flush_console(true);
 			else {
 #ifdef OPAL_DEBUG_CONSOLE_POLL
 				if (debug < 5) {
diff --git a/include/console.h b/include/console.h
index 791f770..8a47bad 100644
--- a/include/console.h
+++ b/include/console.h
@@ -17,6 +17,7 @@
 #ifndef __CONSOLE_H
 #define __CONSOLE_H
 
+#include "unistd.h"
 #include <lock.h>
 
 /*
@@ -56,9 +57,11 @@ extern struct lock con_lock;
 extern bool dummy_console_enabled(void);
 extern void force_dummy_console(void);
 extern bool flush_console(void);
-extern bool __flush_console(void);
+extern bool __flush_console(bool flush_to_drivers);
 extern void set_console(struct con_ops *driver);
 
+ssize_t console_write(bool flush_to_drivers, const void *buf, size_t count);
+
 extern void clear_console(void);
 extern void memcons_add_properties(void);
 extern void dummy_console_add_nodes(void);