| From 716bb4f84cfd4d0e9c5edbeda89863b9d8e4b44c Mon Sep 17 00:00:00 2001 |
| From: =?UTF-8?q?Jan=20H=C3=B6ppner?= <hoeppner@linux.ibm.com> |
| Date: Thu, 19 Dec 2019 09:43:50 +0100 |
| Subject: [PATCH] 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 |
| |
| commit dd4b3c83b9efac10d48a94c61372119fc555a077 upstream. |
| |
| 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 Hรถppner <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: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c |
| index c09039eea707..7b1a71716b54 100644 |
| --- a/drivers/s390/block/dasd_eckd.c |
| +++ b/drivers/s390/block/dasd_eckd.c |
| @@ -1135,7 +1135,8 @@ 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; |
| @@ -1149,7 +1150,7 @@ 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 { |
| @@ -1160,12 +1161,12 @@ 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 4435ae0b3027..f0cae1973f78 100644 |
| --- a/drivers/s390/cio/device_ops.c |
| +++ b/drivers/s390/cio/device_ops.c |
| @@ -624,7 +624,7 @@ 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) |
| { |
| -- |
| 2.7.4 |
| |
