diff options
authorJan Höppner <hoeppner@linux.ibm.com>2019-12-19 09:43:50 +0100
committerJens Axboe <axboe@kernel.dk>2019-12-20 11:52:01 -0700
commitdd4b3c83b9efac10d48a94c61372119fc555a077 (patch)
parentblock: Fix a lockdep complaint triggered by request queue flushing (diff)
s390/dasd/cio: Interpret ccw_device_get_mdc return value correctly
The max data count (mdc) is an unsigned 16-bit integer value as per AR documentation and is received via ccw_device_get_mdc() for a specific path mask from the CIO layer. The function itself also always returns a positive mdc value or 0 in case mdc isn't supported or couldn't be determined. Though, the comment for this function describes a negative return value to indicate failures. As a result, the DASD device driver interprets the return value of ccw_device_get_mdc() incorrectly. The error case is essentially a dead code path. To fix this behaviour, check explicitly for a return value of 0 and change the comment for ccw_device_get_mdc() accordingly. This fix merely enables the error code path in the DASD functions get_fcx_max_data() and verify_fcx_max_data(). The actual functionality stays the same and is still correct. Reviewed-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com> Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com> Reviewed-by: Stefan Haberland <sth@linux.ibm.com> Signed-off-by: Stefan Haberland <sth@linux.ibm.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2 files changed, 6 insertions, 5 deletions
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index c94184d080f8..f5622f4a2ecf 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -1128,7 +1128,8 @@ static u32 get_fcx_max_data(struct dasd_device *device)
struct dasd_eckd_private *private = device->private;
int fcx_in_css, fcx_in_gneq, fcx_in_features;
- int tpm, mdc;
+ unsigned int mdc;
+ int tpm;
if (dasd_nofcx)
return 0;
@@ -1142,7 +1143,7 @@ static u32 get_fcx_max_data(struct dasd_device *device)
return 0;
mdc = ccw_device_get_mdc(device->cdev, 0);
- if (mdc < 0) {
+ if (mdc == 0) {
dev_warn(&device->cdev->dev, "Detecting the maximum supported data size for zHPF requests failed\n");
return 0;
} else {
@@ -1153,12 +1154,12 @@ static u32 get_fcx_max_data(struct dasd_device *device)
static int verify_fcx_max_data(struct dasd_device *device, __u8 lpm)
struct dasd_eckd_private *private = device->private;
- int mdc;
+ unsigned int mdc;
u32 fcx_max_data;
if (private->fcx_max_data) {
mdc = ccw_device_get_mdc(device->cdev, lpm);
- if ((mdc < 0)) {
+ if (mdc == 0) {
"Detecting the maximum data size for zHPF "
"requests failed (rc=%d) for a new path %x\n",
diff --git a/drivers/s390/cio/device_ops.c b/drivers/s390/cio/device_ops.c
index 65841af15748..ccecf6b9504e 100644
--- a/drivers/s390/cio/device_ops.c
+++ b/drivers/s390/cio/device_ops.c
@@ -635,7 +635,7 @@ EXPORT_SYMBOL(ccw_device_tm_start_timeout);
* @mask: mask of paths to use
* Return the number of 64K-bytes blocks all paths at least support
- * for a transport command. Return values <= 0 indicate failures.
+ * for a transport command. Return value 0 indicates failure.
int ccw_device_get_mdc(struct ccw_device *cdev, u8 mask)