X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=drivers%2Fs390%2Fchar%2Fmonwriter.c;h=a86c0534cd49f337dbceb8ef2dab3ac2e0115688;hb=f4798748dee00c807a63f5518f08b3df161e0f6d;hp=268598ef3efe9ada78e23881b416ce6ef933b44e;hpb=cbe56159a3e60624b5f44cf48b640fa470436e34;p=linux-2.6-omap-h63xx.git

diff --git a/drivers/s390/char/monwriter.c b/drivers/s390/char/monwriter.c
index 268598ef3ef..a86c0534cd4 100644
--- a/drivers/s390/char/monwriter.c
+++ b/drivers/s390/char/monwriter.c
@@ -17,6 +17,7 @@
 #include <linux/miscdevice.h>
 #include <linux/ctype.h>
 #include <linux/poll.h>
+#include <linux/mutex.h>
 #include <asm/uaccess.h>
 #include <asm/ebcdic.h>
 #include <asm/io.h>
@@ -41,6 +42,7 @@ struct mon_private {
 	size_t hdr_to_read;
 	size_t data_to_read;
 	struct mon_buf *current_buf;
+	struct mutex thread_mutex;
 };
 
 /*
@@ -179,6 +181,7 @@ static int monwrite_open(struct inode *inode, struct file *filp)
 		return -ENOMEM;
 	INIT_LIST_HEAD(&monpriv->list);
 	monpriv->hdr_to_read = sizeof(monpriv->hdr);
+	mutex_init(&monpriv->thread_mutex);
 	filp->private_data = monpriv;
 	return nonseekable_open(inode, filp);
 }
@@ -209,6 +212,7 @@ static ssize_t monwrite_write(struct file *filp, const char __user *data,
 	void *to;
 	int rc;
 
+	mutex_lock(&monpriv->thread_mutex);
 	for (written = 0; written < count; ) {
 		if (monpriv->hdr_to_read) {
 			len = min(count - written, monpriv->hdr_to_read);
@@ -247,11 +251,13 @@ static ssize_t monwrite_write(struct file *filp, const char __user *data,
 		}
 		monpriv->hdr_to_read = sizeof(monpriv->hdr);
 	}
+	mutex_unlock(&monpriv->thread_mutex);
 	return written;
 
 out_error:
 	monpriv->data_to_read = 0;
 	monpriv->hdr_to_read = sizeof(struct monwrite_hdr);
+	mutex_unlock(&monpriv->thread_mutex);
 	return rc;
 }
 
@@ -289,7 +295,7 @@ module_init(mon_init);
 module_exit(mon_exit);
 
 module_param_named(max_bufs, mon_max_bufs, int, 0644);
-MODULE_PARM_DESC(max_bufs, "Maximum number of sample monitor data buffers"
+MODULE_PARM_DESC(max_bufs, "Maximum number of sample monitor data buffers "
 		 "that can be active at one time");
 
 MODULE_AUTHOR("Melissa Howland <Melissa.Howland@us.ibm.com>");