[PATCH V4 2/3] nvmet: make ctrl model configurable

[Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>]

From: Mark Ruijter <MRuijter@onestopsystems.com>

This patch adds a new target subsys attribute which allows user to
optionally specify model name which then used in the
nvmet_execute_identify_ctrl() to fill up the nvme_id_ctrl structure.

The default value for the model is set to "Linux" for backward
compatibility.

Signed-off-by: Mark Ruijter <MRuijter@onestopsystems.com>
[use macro for default model, coding style fixes]
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---
Changes from V3:-

1, Update commit description with additional changes on the top of
   original patch.
2. Reduce the size of the lock in nvmet_subsys_attr_model_store().
3. Don't initialize subsys->model = NULL nvmet_subsys_alloc().

Changes from V2:-

1. Use if else pattern than ternary operators.
2. Change the name nvmet_subsys_model() -> nvmet_model_number().
3. Introduce nvmet_is_ascii() to filter the model characters.
4. Change tmp -> tmp_model in nvmet_subsys_attr_model_store().

Changes from V1:-

1. Don't allocate memory for default subsys model,
2. Use helper to get the default model string from ctrl->subsys in the
   nvmet_execute_identify_ctrl() and nvmet_subsys_attr_model()_show.
   Later is needed so that nvmetcli can display default value Linux
   when the model is not set from the user.
3. Get rid of the extra variable c in the nvmet_subsys_attr_model_store()
   and replace for with while loop without loosing the code redability.
---
 drivers/nvme/target/admin-cmd.c | 12 +++++++--
 drivers/nvme/target/configfs.c  | 46 +++++++++++++++++++++++++++++++++
 drivers/nvme/target/core.c      |  1 +
 drivers/nvme/target/nvmet.h     |  4 +++
 4 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index 56c21b501185..613e715dc7d3 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -312,12 +312,20 @@ static void nvmet_execute_get_log_page(struct nvmet_req *req)
 	nvmet_req_complete(req, NVME_SC_INVALID_FIELD | NVME_SC_DNR);
 }
 
+const char *nvmet_model_number(struct nvmet_subsys *subsys)
+{
+	if (subsys->model)
+		return subsys->model;
+
+	return NVMET_DEFAULT_CTRL_MODEL;
+}
+
 static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 {
+	const char *model = nvmet_model_number(req->sq->ctrl->subsys);
 	struct nvmet_ctrl *ctrl = req->sq->ctrl;
 	struct nvme_id_ctrl *id;
 	u16 status = 0;
-	const char model[] = "Linux";
 
 	id = kzalloc(sizeof(*id), GFP_KERNEL);
 	if (!id) {
@@ -332,7 +340,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	memset(id->sn, ' ', sizeof(id->sn));
 	bin2hex(id->sn, &ctrl->subsys->serial,
 		min(sizeof(ctrl->subsys->serial), sizeof(id->sn) / 2));
-	memcpy_and_pad(id->mn, sizeof(id->mn), model, sizeof(model) - 1, ' ');
+	memcpy_and_pad(id->mn, sizeof(id->mn), model, strlen(model), ' ');
 	memcpy_and_pad(id->fr, sizeof(id->fr),
 		       UTS_RELEASE, strlen(UTS_RELEASE), ' ');
 
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 772a74a7d969..4dea77a7da3e 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -932,12 +932,58 @@ static ssize_t nvmet_subsys_attr_cntlid_max_store(struct config_item *item,
 }
 CONFIGFS_ATTR(nvmet_subsys_, attr_cntlid_max);
 
+static ssize_t nvmet_subsys_attr_model_show(struct config_item *item,
+					    char *page)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+
+	return snprintf(page, PAGE_SIZE, "%s\n",
+			nvmet_model_number(subsys));
+}
+
+/* See Section 1.5 of NVMe 1.4 */
+static bool nvmet_is_ascii(const char c)
+{
+	return c >= 0x20 && c <= 0x7e;
+}
+
+static ssize_t nvmet_subsys_attr_model_store(struct config_item *item,
+					     const char *page, size_t count)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	int pos = 0, len;
+	char *tmp_model;
+
+	len = strcspn(page, "\n");
+	if (!len)
+		return -EINVAL;
+
+	for (pos = 0; pos < len; pos++) {
+		if (!nvmet_is_ascii(page[pos]))
+			return -EINVAL;
+	}
+
+	tmp_model = kstrndup(page, len, GFP_KERNEL);
+	if (!tmp_model)
+		return -ENOMEM;
+
+	down_write(&nvmet_config_sem);
+	kfree(subsys->model);
+	subsys->model = tmp_model;
+	up_write(&nvmet_config_sem);
+
+	return count;
+}
+
+CONFIGFS_ATTR(nvmet_subsys_, attr_model);
+
 static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_allow_any_host,
 	&nvmet_subsys_attr_attr_version,
 	&nvmet_subsys_attr_attr_serial,
 	&nvmet_subsys_attr_attr_cntlid_min,
 	&nvmet_subsys_attr_attr_cntlid_max,
+	&nvmet_subsys_attr_attr_model,
 	NULL,
 };
 
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 387628ec7e37..c041d88ed3ea 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1436,6 +1436,7 @@ static void nvmet_subsys_free(struct kref *ref)
 	WARN_ON_ONCE(!list_empty(&subsys->namespaces));
 
 	kfree(subsys->subsysnqn);
+	kfree(subsys->model);
 	kfree(subsys);
 }
 
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 6492d12e626a..c54ce5f66f09 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -23,6 +23,7 @@
 #define NVMET_ASYNC_EVENTS		4
 #define NVMET_ERROR_LOG_SLOTS		128
 #define NVMET_NO_ERROR_LOC		((u16)-1)
+#define NVMET_DEFAULT_CTRL_MODEL	"Linux"
 
 /*
  * Supported optional AENs:
@@ -224,6 +225,7 @@ struct nvmet_subsys {
 	u64			ver;
 	u64			serial;
 	char			*subsysnqn;
+	char			*model;
 
 	struct config_group	group;
 
@@ -489,6 +491,8 @@ u16 nvmet_bdev_flush(struct nvmet_req *req);
 u16 nvmet_file_flush(struct nvmet_req *req);
 void nvmet_ns_changed(struct nvmet_subsys *subsys, u32 nsid);
 
+const char *nvmet_model_number(struct nvmet_subsys *subsys);
+
 static inline u32 nvmet_rw_len(struct nvmet_req *req)
 {
 	return ((u32)le16_to_cpu(req->cmd->rw.length) + 1) <<
-- 
2.22.1


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