| From 3cc2a0bb4c8c430312fe9df77b4f838df6303825 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 19 Dec 2019 09:43:50 +0100 |
| Subject: s390/dasd/cio: Interpret ccw_device_get_mdc return value correctly |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| From: Jan Höppner <hoeppner@linux.ibm.com> |
| |
| [ Upstream commit dd4b3c83b9efac10d48a94c61372119fc555a077 ] |
| |
| 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> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/s390/block/dasd_eckd.c | 9 +++++---- |
| drivers/s390/cio/device_ops.c | 2 +- |
| 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) { |
| dev_warn(&device->cdev->dev, |
| "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) |
| { |
| -- |
| 2.20.1 |
| |