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Subject[PATCH v2] device-dax: Auto-bind device after successful new_id
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Date
The typical 'new_id' attribute behavior is to immediately attach a
device to its driver after a new device-id is added. Implement this
behavior for the dax bus.

Reported-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Reported-by: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
Changes since v1:
* Fix the remove_id path since do_id_store() is shared with the new_id
path (Brice)

Brice, this works for me. I'll push it out on libnvdimm-pending, or in
the meantime you can apply this patch after reverting commit
a9f1ffdb6a20 on the current state of the branch.

drivers/dax/bus.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index c620ad52d7e5..a410154d75fb 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -57,8 +57,13 @@ static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
return match;
}

+enum id_action {
+ ID_REMOVE,
+ ID_ADD,
+};
+
static ssize_t do_id_store(struct device_driver *drv, const char *buf,
- size_t count, bool add)
+ size_t count, enum id_action action)
{
struct dax_device_driver *dax_drv = to_dax_drv(drv);
unsigned int region_id, id;
@@ -77,7 +82,7 @@ static ssize_t do_id_store(struct device_driver *drv, const char *buf,
mutex_lock(&dax_bus_lock);
dax_id = __dax_match_id(dax_drv, buf);
if (!dax_id) {
- if (add) {
+ if (action == ID_ADD) {
dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
if (dax_id) {
strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
@@ -86,26 +91,33 @@ static ssize_t do_id_store(struct device_driver *drv, const char *buf,
rc = -ENOMEM;
} else
/* nothing to remove */;
- } else if (!add) {
+ } else if (action == ID_REMOVE) {
list_del(&dax_id->list);
kfree(dax_id);
} else
/* dax_id already added */;
mutex_unlock(&dax_bus_lock);
- return rc;
+
+ if (rc < 0)
+ return rc;
+ if (action == ID_ADD)
+ rc = driver_attach(drv);
+ if (rc)
+ return rc;
+ return count;
}

static ssize_t new_id_store(struct device_driver *drv, const char *buf,
size_t count)
{
- return do_id_store(drv, buf, count, true);
+ return do_id_store(drv, buf, count, ID_ADD);
}
static DRIVER_ATTR_WO(new_id);

static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
size_t count)
{
- return do_id_store(drv, buf, count, false);
+ return do_id_store(drv, buf, count, ID_REMOVE);
}
static DRIVER_ATTR_WO(remove_id);

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