From: Michael Holzheu <holzheu@de.ibm.com>
Date: Fri, 10 Aug 2007 12:32:33 +0000 (+0200)
Subject: [S390] vmur: add "top of queue" sanity check for reader open
X-Git-Tag: firefly_0821_release~26789^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4eac34529bce2b4cca9be90a6903c965baa8193c;p=firefly-linux-kernel-4.4.55.git

[S390] vmur: add "top of queue" sanity check for reader open

If the z/VM reader is already open, it can happen that after opening the
Linux reader device, not the topmost file is processed. According the
semantics of the Linux z/VM unit record device driver, always the topmost
file has to be processed. With this fix an error is returned if that is
not the case.

Signed-off-by: Michael Holzheu <holzheu@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/char/vmur.c b/drivers/s390/char/vmur.c
index 04395c0f99d8..a9d58629e795 100644
--- a/drivers/s390/char/vmur.c
+++ b/drivers/s390/char/vmur.c
@@ -565,9 +565,14 @@ static int verify_device(struct urdev *urd)
 			return -ENOMEM;
 		rc = diag_read_file(urd->dev_id.devno, buf);
 		kfree(buf);
-
 		if ((rc != 0) && (rc != -ENODATA)) /* EOF does not hurt */
 			return rc;
+		/* check if the file on top of the queue is open now */
+		rc = diag_read_next_file_info(&fcb, 0);
+		if (rc)
+			return rc;
+		if (!(fcb.file_stat & FLG_IN_USE))
+			return -EMFILE;
 		return 0;
 	default:
 		return -ENOTSUPP;
diff --git a/drivers/s390/char/vmur.h b/drivers/s390/char/vmur.h
index 522a9dfaa275..2b3c564e0472 100644
--- a/drivers/s390/char/vmur.h
+++ b/drivers/s390/char/vmur.h
@@ -53,6 +53,7 @@ struct file_control_block {
 #define FLG_SYSTEM_HOLD	0x04
 #define FLG_CP_DUMP	0x10
 #define FLG_USER_HOLD	0x20
+#define FLG_IN_USE	0x80
 
 /*
  * A struct urdev is created for each ur device that is made available