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authorCornelia Huck <cohuck@redhat.com>2019-06-13 13:08:15 +0200
committerVasily Gorbik <gor@linux.ibm.com>2019-07-02 16:00:26 +0200
commitebc3d179150347f3b6d97d8f249378bb2218f95e (patch)
treefd608926e7c655a331816d91722b45ef4cec11e5 /drivers/s390/cio
parentvfio-ccw: make convert_ccw0_to_ccw1 static (diff)
downloadlinux-dev-ebc3d179150347f3b6d97d8f249378bb2218f95e.tar.xz
linux-dev-ebc3d179150347f3b6d97d8f249378bb2218f95e.zip
s390/cio: introduce driver_override on the css bus
Sometimes, we want to control which of the matching drivers binds to a subchannel device (e.g. for subchannels we want to handle via vfio-ccw). For pci devices, a mechanism to do so has been introduced in 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override"). It makes sense to introduce the driver_override attribute for subchannel devices as well, so that we can easily extend the 'driverctl' tool (which makes use of the driver_override attribute for pci). Note that unlike pci we still require a driver override to match the subchannel type; matching more than one subchannel type is probably not useful anyway. Signed-off-by: Cornelia Huck <cohuck@redhat.com> Reviewed-by: Halil Pasic <pasic@linux.ibm.com> Reviewed-by: Sebastian Ott <sebott@linux.ibm.com> Signed-off-by: Sebastian Ott <sebott@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'drivers/s390/cio')
-rw-r--r--drivers/s390/cio/cio.h1
-rw-r--r--drivers/s390/cio/css.c53
2 files changed, 54 insertions, 0 deletions
diff --git a/drivers/s390/cio/cio.h b/drivers/s390/cio/cio.h
index 4d6c7d16416e..ba7d2480613b 100644
--- a/drivers/s390/cio/cio.h
+++ b/drivers/s390/cio/cio.h
@@ -113,6 +113,7 @@ struct subchannel {
enum sch_todo todo;
struct work_struct todo_work;
struct schib_config config;
+ char *driver_override; /* Driver name to force a match */
} __attribute__ ((aligned(8)));
DECLARE_PER_CPU_ALIGNED(struct irb, cio_irb);
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 7159933d9d3e..e1f2d0eed544 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -167,6 +167,7 @@ static void css_subchannel_release(struct device *dev)
sch->config.intparm = 0;
cio_commit_config(sch);
+ kfree(sch->driver_override);
kfree(sch->lock);
kfree(sch);
}
@@ -323,9 +324,57 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
static DEVICE_ATTR_RO(modalias);
+static ssize_t driver_override_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct subchannel *sch = to_subchannel(dev);
+ char *driver_override, *old, *cp;
+
+ /* We need to keep extra room for a newline */
+ if (count >= (PAGE_SIZE - 1))
+ return -EINVAL;
+
+ driver_override = kstrndup(buf, count, GFP_KERNEL);
+ if (!driver_override)
+ return -ENOMEM;
+
+ cp = strchr(driver_override, '\n');
+ if (cp)
+ *cp = '\0';
+
+ device_lock(dev);
+ old = sch->driver_override;
+ if (strlen(driver_override)) {
+ sch->driver_override = driver_override;
+ } else {
+ kfree(driver_override);
+ sch->driver_override = NULL;
+ }
+ device_unlock(dev);
+
+ kfree(old);
+
+ return count;
+}
+
+static ssize_t driver_override_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct subchannel *sch = to_subchannel(dev);
+ ssize_t len;
+
+ device_lock(dev);
+ len = snprintf(buf, PAGE_SIZE, "%s\n", sch->driver_override);
+ device_unlock(dev);
+ return len;
+}
+static DEVICE_ATTR_RW(driver_override);
+
static struct attribute *subch_attrs[] = {
&dev_attr_type.attr,
&dev_attr_modalias.attr,
+ &dev_attr_driver_override.attr,
NULL,
};
@@ -1348,6 +1397,10 @@ static int css_bus_match(struct device *dev, struct device_driver *drv)
struct css_driver *driver = to_cssdriver(drv);
struct css_device_id *id;
+ /* When driver_override is set, only bind to the matching driver */
+ if (sch->driver_override && strcmp(sch->driver_override, drv->name))
+ return 0;
+
for (id = driver->subchannel_type; id->match_flags; id++) {
if (sch->st == id->type)
return 1;