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[S390] monwriter: Serialization bug for multithreaded applications.

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

Signed-off-by: Melissa Howland <melissah@us.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Melissa Howland
2007-08-10 14:32:35 +02:00
committed by Martin Schwidefsky
parent 3eed13cc3b
commit cbea66d978
1 changed files with 6 additions and 0 deletions
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6
drivers/s390/char/monwriter.c
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@@ -17,6 +17,7 @@
#include <linux/miscdevice.h> #include <linux/miscdevice.h>
#include <linux/ctype.h> #include <linux/ctype.h>
#include <linux/poll.h> #include <linux/poll.h>
#include <linux/mutex.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
#include <asm/ebcdic.h> #include <asm/ebcdic.h>
#include <asm/io.h> #include <asm/io.h>
@@ -41,6 +42,7 @@ struct mon_private {
size_t hdr_to_read; size_t hdr_to_read;
size_t data_to_read; size_t data_to_read;
struct mon_buf *current_buf; 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; return -ENOMEM;
INIT_LIST_HEAD(&monpriv->list); INIT_LIST_HEAD(&monpriv->list);
monpriv->hdr_to_read = sizeof(monpriv->hdr); monpriv->hdr_to_read = sizeof(monpriv->hdr);
mutex_init(&monpriv->thread_mutex);
filp->private_data = monpriv; filp->private_data = monpriv;
return nonseekable_open(inode, filp); return nonseekable_open(inode, filp);
} }
@@ -209,6 +212,7 @@ static ssize_t monwrite_write(struct file *filp, const char __user *data,
void *to; void *to;
int rc; int rc;
mutex_lock(&monpriv->thread_mutex);
for (written = 0; written < count; ) { for (written = 0; written < count; ) {
if (monpriv->hdr_to_read) { if (monpriv->hdr_to_read) {
len = min(count - written, 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); monpriv->hdr_to_read = sizeof(monpriv->hdr);
} }
mutex_unlock(&monpriv->thread_mutex);
return written; return written;
out_error: out_error:
monpriv->data_to_read = 0; monpriv->data_to_read = 0;
monpriv->hdr_to_read = sizeof(struct monwrite_hdr); monpriv->hdr_to_read = sizeof(struct monwrite_hdr);
mutex_unlock(&monpriv->thread_mutex);
return rc; return rc;
} }