linux-kernel - [PATCH 04/12] xen: make use of xenbus_read

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Message-Id: <1477932510-28594-5-git-send-email-jgross@suse.com>
Date:   Mon, 31 Oct 2016 17:48:22 +0100
From:   Juergen Gross <jgross@...e.com>
To:     linux-kernel@...r.kernel.org, xen-devel@...ts.xen.org
Cc:     david.vrabel@...rix.com, boris.ostrovsky@...cle.com,
        Juergen Gross <jgross@...e.com>, peterhuewe@....de,
        tpmdd@...horst.net, jarkko.sakkinen@...ux.intel.com,
        jgunthorpe@...idianresearch.com, tpmdd-devel@...ts.sourceforge.net
Subject: [PATCH 04/12] xen: make use of xenbus_read_unsigned() in xen-tpmfront

Use xenbus_read_unsigned() instead of xenbus_scanf() when possible.
This requires to change the type of one read from int to unsigned,
but this case has been wrong before: negative values are not allowed
for the modified case.

Cc: peterhuewe@....de
Cc: tpmdd@...horst.net
Cc: jarkko.sakkinen@...ux.intel.com
Cc: jgunthorpe@...idianresearch.com
Cc: tpmdd-devel@...ts.sourceforge.net

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 drivers/char/tpm/xen-tpmfront.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index 62028f4..50072cc 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -337,18 +337,14 @@ static int tpmfront_resume(struct xenbus_device *dev)
 static void backend_changed(struct xenbus_device *dev,
 		enum xenbus_state backend_state)
 {
-	int val;
-
 	switch (backend_state) {
 	case XenbusStateInitialised:
 	case XenbusStateConnected:
 		if (dev->state == XenbusStateConnected)
 			break;
 
-		if (xenbus_scanf(XBT_NIL, dev->otherend,
-				"feature-protocol-v2", "%d", &val) < 0)
-			val = 0;
-		if (!val) {
+		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
+					  0)) {
 			xenbus_dev_fatal(dev, -EINVAL,
 					"vTPM protocol 2 required");
 			return;
-- 
2.6.6