uml: sysrq and mconsole fixes

Fix the passing of printk output back to the mconsole client.  The existing
code was somewhat confused, accumulating output in a buffer, but writing it
out entirely whenever a new chunk was added.  This is fixed.

The earlier include cleanups caused linux/sysrq.h to not be included - this is
fixed by adding the include back, under CONFIG_MAGIC_SYSRQ.

CONFIG_MAGIC_SYSRQ is also defaulted to on in defconfig.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 10 insertions, 15 deletions

diff --git a/arch/um/defconfig b/arch/um/defconfig
index ed3196d8c908..658f65446c56 100644
--- a/arch/um/defconfig
+++ b/arch/um/defconfig
@@ -80,7 +80,7 @@ CONFIG_BINFMT_MISC=m
 # CONFIG_HOSTFS is not set
 # CONFIG_HPPFS is not set
 CONFIG_MCONSOLE=y
-# CONFIG_MAGIC_SYSRQ is not set
+CONFIG_MAGIC_SYSRQ=y
 CONFIG_NEST_LEVEL=0
 # CONFIG_HIGHMEM is not set
 CONFIG_KERNEL_STACK_ORDER=0
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 5f6dbb148218..642bee2eeaf5 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -632,10 +632,9 @@ struct mconsole_output {
 static DEFINE_SPINLOCK(client_lock);
 static LIST_HEAD(clients);
 static char console_buf[MCONSOLE_MAX_DATA];
-static int console_index = 0;
 
 static void console_write(struct console *console, const char *string,
-                          unsigned len)
+                          unsigned int len)
 {
         struct list_head *ele;
         int n;
@@ -643,24 +642,18 @@ static void console_write(struct console *console, const char *string,
         if (list_empty(&clients))
                 return;
 
-        while (1) {
-                n = min((size_t) len, ARRAY_SIZE(console_buf) - console_index);
-                strncpy(&console_buf[console_index], string, n);
-                console_index += n;
+        while (len > 0) {
+                n = min((size_t) len, ARRAY_SIZE(console_buf));
+                strncpy(console_buf, string, n);
                 string += n;
                 len -= n;
-                if (len == 0)
-                        return;
 
                 list_for_each(ele, &clients) {
                         struct mconsole_output *entry;
 
                         entry = list_entry(ele, struct mconsole_output, list);
-                        mconsole_reply_len(entry->req, console_buf,
-                                           console_index, 0, 1);
+                        mconsole_reply_len(entry->req, console_buf, n, 0, 1);
                 }
-
-                console_index = 0;
         }
 }
 
@@ -690,8 +683,7 @@ static void with_console(struct mc_request *req, void (*proc)(void *),
 
         (*proc)(arg);
 
-        mconsole_reply_len(req, console_buf, console_index, 0, 0);
-        console_index = 0;
+        mconsole_reply_len(req, "", 0, 0, 0);
 
         spin_lock_irqsave(&client_lock, flags);
         list_del(&entry.list);
@@ -699,6 +691,9 @@ static void with_console(struct mc_request *req, void (*proc)(void *),
 }
 
 #ifdef CONFIG_MAGIC_SYSRQ
+
+#include <linux/sysrq.h>
+
 static void sysrq_proc(void *arg)
 {
         char *op = arg;