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Commit cbea66d9 authored by Melissa Howland's avatar Melissa Howland Committed by Martin Schwidefsky
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[S390] monwriter: Serialization bug for multithreaded applications. 



Locking added so that multithreaded applications can now do writes
from different threads without the risk of storage corruption.

Signed-off-by: default avatarMelissa Howland <melissah@us.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 3eed13cc

drivers/s390/char/monwriter.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

}