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| author | Jan Höppner <hoeppner@linux.ibm.com> | 2019-12-19 11:43:50 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-12 14:12:00 +0300 |
| commit | 29753fc2f8d0b406f2435c53f5e49c959c381ac5 (patch) | |
| tree | 9c688dbd26efe9a237b006f876d842de562fb86e /drivers/s390/block | |
| parent | f1cf84a64527c94c24e009e73bf2c38ce2361596 (diff) | |
| download | linux-29753fc2f8d0b406f2435c53f5e49c959c381ac5.tar.xz | |
s390/dasd/cio: Interpret ccw_device_get_mdc return value correctly
[ 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>
Diffstat (limited to 'drivers/s390/block')
| -rw-r--r-- | drivers/s390/block/dasd_eckd.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c index 0d5e2d92e05b..81359312a987 100644 --- a/drivers/s390/block/dasd_eckd.c +++ b/drivers/s390/block/dasd_eckd.c @@ -1133,7 +1133,8 @@ 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; @@ -1147,7 +1148,7 @@ 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 { @@ -1158,12 +1159,12 @@ 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", |