greybus: fw-download: Manage firmware requests with kref

This patch updates the fw-download core to manage firmware requests with
kref. This is required for the next patch, which will introduce timeouts
for firmware downloads.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/fw-download.c b/drivers/staging/greybus/fw-download.c
index e60abde2d70484dad6883e29b3ecf1a8c212f4fc..6bd26180bca6fa8b453b71e30e19f8cd651a4d82 100644 (file)
--- a/drivers/staging/greybus/fw-download.c
+++ b/drivers/staging/greybus/fw-download.c
@@ -19,6 +19,9 @@ struct fw_request {
        char                    name[FW_NAME_LEN];
        const struct firmware   *fw;
        struct list_head        node;
+
+       struct kref             kref;
+       struct fw_download      *fw_download;
 };
 
 struct fw_download {
@@ -28,26 +31,49 @@ struct fw_download {
        struct ida              id_map;
 };
 
-static struct fw_request *match_firmware(struct fw_download *fw_download,
-                                        u8 firmware_id)
+static void fw_req_release(struct kref *kref)
+{
+       struct fw_request *fw_req = container_of(kref, struct fw_request, kref);
+
+       dev_dbg(fw_req->fw_download->parent, "firmware %s released\n",
+               fw_req->name);
+
+       release_firmware(fw_req->fw);
+       ida_simple_remove(&fw_req->fw_download->id_map, fw_req->firmware_id);
+       kfree(fw_req);
+}
+
+/* Caller must call put_fw_req() after using struct fw_request */
+static struct fw_request *get_fw_req(struct fw_download *fw_download,
+                                    u8 firmware_id)
 {
        struct fw_request *fw_req;
 
        list_for_each_entry(fw_req, &fw_download->fw_requests, node) {
-               if (fw_req->firmware_id == firmware_id)
+               if (fw_req->firmware_id == firmware_id) {
+                       kref_get(&fw_req->kref);
                        return fw_req;
+               }
        }
 
        return NULL;
 }
 
+/*
+ * Incoming requests are serialized for a connection, and this will never be
+ * racy.
+ */
+static void put_fw_req(struct fw_request *fw_req)
+{
+       kref_put(&fw_req->kref, fw_req_release);
+}
+
 static void free_firmware(struct fw_download *fw_download,
                          struct fw_request *fw_req)
 {
        list_del(&fw_req->node);
-       release_firmware(fw_req->fw);
-       ida_simple_remove(&fw_download->id_map, fw_req->firmware_id);
-       kfree(fw_req);
+
+       put_fw_req(fw_req);
 }
 
 /* This returns path of the firmware blob on the disk */
@@ -87,6 +113,8 @@ static struct fw_request *find_firmware(struct fw_download *fw_download,
                goto err_free_id;
        }
 
+       fw_req->fw_download = fw_download;
+       kref_init(&fw_req->kref);
        list_add(&fw_req->node, &fw_download->fw_requests);
 
        return fw_req;
@@ -155,6 +183,7 @@ static int fw_download_fetch_firmware(struct gb_operation *op)
        const struct firmware *fw;
        unsigned int offset, size;
        u8 firmware_id;
+       int ret = 0;
 
        if (op->request->payload_size != sizeof(*request)) {
                dev_err(fw_download->parent,
@@ -168,7 +197,7 @@ static int fw_download_fetch_firmware(struct gb_operation *op)
        size = le32_to_cpu(request->size);
        firmware_id = request->firmware_id;
 
-       fw_req = match_firmware(fw_download, firmware_id);
+       fw_req = get_fw_req(fw_download, firmware_id);
        if (!fw_req) {
                dev_err(fw_download->parent,
                        "firmware not available for id: %02u\n", firmware_id);
@@ -181,14 +210,16 @@ static int fw_download_fetch_firmware(struct gb_operation *op)
                dev_err(fw_download->parent,
                        "bad fetch firmware request (offs = %u, size = %u)\n",
                        offset, size);
-               return -EINVAL;
+               ret = -EINVAL;
+               goto put_fw;
        }
 
        if (!gb_operation_response_alloc(op, sizeof(*response) + size,
                                         GFP_KERNEL)) {
                dev_err(fw_download->parent,
                        "error allocating fetch firmware response\n");
-               return -ENOMEM;
+               ret = -ENOMEM;
+               goto put_fw;
        }
 
        response = op->response->payload;
@@ -198,7 +229,10 @@ static int fw_download_fetch_firmware(struct gb_operation *op)
                "responding with firmware (offs = %u, size = %u)\n", offset,
                size);
 
-       return 0;
+put_fw:
+       put_fw_req(fw_req);
+
+       return ret;
 }
 
 static int fw_download_release_firmware(struct gb_operation *op)
@@ -219,7 +253,7 @@ static int fw_download_release_firmware(struct gb_operation *op)
        request = op->request->payload;
        firmware_id = request->firmware_id;
 
-       fw_req = match_firmware(fw_download, firmware_id);
+       fw_req = get_fw_req(fw_download, firmware_id);
        if (!fw_req) {
                dev_err(fw_download->parent,
                        "firmware not available for id: %02u\n", firmware_id);
@@ -227,6 +261,7 @@ static int fw_download_release_firmware(struct gb_operation *op)
        }
 
        free_firmware(fw_download, fw_req);
+       put_fw_req(fw_req);
 
        dev_dbg(fw_download->parent, "release firmware\n");