diff options
authorVishal Verma <>2019-02-22 16:58:54 -0700
committerDan Williams <>2019-02-27 21:03:48 -0800
commitc347bd71dcdb2d0ac8b3a771486584dca8c8dd80 (patch)
parent21c75763a3ae18679e5c4e2260aa9379b073566b (diff)
device-dax: Add a 'modalias' attribute to DAX 'bus' devices
Add a 'modalias' attribute to devices under the DAX bus so that userspace is able to dynamically load modules as needed. Normally, udev can get the modalias from 'uevent', and that is correctly set up by the DAX bus. However other tooling such as 'libndctl' for interacting with drivers/nvdimm/, and 'libdaxctl' for drivers/dax/ can also use the modalias to dynamically load modules via libkmod lookups. The 'nd' bus set up by the libnvdimm subsystem exports a modalias attribute. Imitate this to export the same for the 'dax' bus. Cc: Dave Hansen <> Signed-off-by: Vishal Verma <> Signed-off-by: Dan Williams <>
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 28c3324271ac..2109cfe80219 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -295,6 +295,17 @@ static ssize_t target_node_show(struct device *dev,
static DEVICE_ATTR_RO(target_node);
+static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+ /*
+ * We only ever expect to handle device-dax instances, i.e. the
+ * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
+ */
+ return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
+static DEVICE_ATTR_RO(modalias);
static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
struct device *dev = container_of(kobj, struct device, kobj);
@@ -306,6 +317,7 @@ static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
static struct attribute *dev_dax_attributes[] = {
+ &dev_attr_modalias.attr,