Merge branch 'timers/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / drivers / s390 / char / monwriter.c

diff --git a/drivers/s390/char/monwriter.c b/drivers/s390/char/monwriter.c
index 9e451ac..4d71aa8 100644 (file)
--- a/drivers/s390/char/monwriter.c
+++ b/drivers/s390/char/monwriter.c
@@ -12,11 +12,13 @@
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/errno.h>
+#include <linux/smp_lock.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #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 +43,7 @@ struct mon_private {
        size_t hdr_to_read;
        size_t data_to_read;
        struct mon_buf *current_buf;
+       struct mutex thread_mutex;
 };
 
 /*
@@ -177,9 +180,12 @@ static int monwrite_open(struct inode *inode, struct file *filp)
        monpriv = kzalloc(sizeof(struct mon_private), GFP_KERNEL);
        if (!monpriv)
                return -ENOMEM;
+       lock_kernel();
        INIT_LIST_HEAD(&monpriv->list);
        monpriv->hdr_to_read = sizeof(monpriv->hdr);
+       mutex_init(&monpriv->thread_mutex);
        filp->private_data = monpriv;
+       unlock_kernel();
        return nonseekable_open(inode, filp);
 }
 
@@ -209,6 +215,7 @@ 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);
@@ -247,15 +254,17 @@ 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;
 }
 
-static struct file_operations monwrite_fops = {
+static const struct file_operations monwrite_fops = {
        .owner   = THIS_MODULE,
        .open    = &monwrite_open,
        .release = &monwrite_close,
@@ -289,7 +298,7 @@ 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>");