firmware loader: let caching firmware piggyback on loading firmware

After starting caching firmware, there is still some time left
before devices are suspended, during the period, request_firmware
or its nowait version may still be triggered by the below situations
to load firmware images which can't be cached during suspend/resume
cycle.

	- new devices added
	- driver bind
	- or device open kind of things

This patch utilizes the piggyback trick to cache firmware for
this kind of situation: just increase the firmware buf's reference
count and add the fw name entry into cache entry list after starting
caching firmware and before syscore_suspend() is called.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 74 insertions, 9 deletions

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index edc88bc68b3d..95f6851b3010 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -25,6 +25,7 @@
 #include <linux/async.h>
 #include <linux/pm.h>
 #include <linux/suspend.h>
+#include <linux/syscore_ops.h>
 
 #include "base.h"
 
@@ -105,6 +106,8 @@ struct firmware_cache {
         spinlock_t name_lock;
         struct list_head fw_names;
 
+        int state;
+
         wait_queue_head_t wait_queue;
         int cnt;
         struct delayed_work work;
@@ -146,6 +149,11 @@ struct fw_name_devm {
 
 #define to_fwbuf(d) container_of(d, struct firmware_buf, ref)
 
+#define FW_LOADER_NO_CACHE      0
+#define FW_LOADER_START_CACHE   1
+
+static int fw_cache_piggyback_on_request(const char *name);
+
 /* fw_lock could be moved to 'struct firmware_priv' but since it is just
  * guarding for corner cases a global lock should be OK */
 static DEFINE_MUTEX(fw_lock);
@@ -741,6 +749,7 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
         int retval = 0;
         struct device *f_dev = &fw_priv->dev;
         struct firmware_buf *buf = fw_priv->buf;
+        struct firmware_cache *fwc = &fw_cache;
 
         dev_set_uevent_suppress(f_dev, true);
 
@@ -796,6 +805,15 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent,
         if (!retval)
                 retval = fw_map_pages_buf(buf);
 
+        /*
+         * After caching firmware image is started, let it piggyback
+         * on request firmware.
+         */
+        if (!retval && fwc->state == FW_LOADER_START_CACHE) {
+                if (fw_cache_piggyback_on_request(buf->fw_id))
+                        kref_get(&buf->ref);
+        }
+
         /* pass the pages buffer to driver at the last minute */
         fw_set_page_data(buf, fw_priv->fw);
 
@@ -1041,6 +1059,29 @@ exit:
         return fce;
 }
 
+static int fw_cache_piggyback_on_request(const char *name)
+{
+        struct firmware_cache *fwc = &fw_cache;
+        struct fw_cache_entry *fce;
+        int ret = 0;
+
+        spin_lock(&fwc->name_lock);
+        list_for_each_entry(fce, &fwc->fw_names, list) {
+                if (!strcmp(fce->name, name))
+                        goto found;
+        }
+
+        fce = alloc_fw_cache_entry(name);
+        if (fce) {
+                ret = 1;
+                list_add(&fce->list, &fwc->fw_names);
+                pr_debug("%s: fw: %s\n", __func__, name);
+        }
+found:
+        spin_unlock(&fwc->name_lock);
+        return ret;
+}
+
 static void free_fw_cache_entry(struct fw_cache_entry *fce)
 {
         kfree(fce);
@@ -1054,17 +1095,14 @@ static void __async_dev_cache_fw_image(void *fw_entry,
         int ret;
 
         ret = cache_firmware(fce->name);
-        if (ret)
-                goto free;
+        if (ret) {
+                spin_lock(&fwc->name_lock);
+                list_del(&fce->list);
+                spin_unlock(&fwc->name_lock);
 
-        spin_lock(&fwc->name_lock);
-        list_add(&fce->list, &fwc->fw_names);
-        spin_unlock(&fwc->name_lock);
-        goto drop_ref;
+                free_fw_cache_entry(fce);
+        }
 
-free:
-        free_fw_cache_entry(fce);
-drop_ref:
         spin_lock(&fwc->name_lock);
         fwc->cnt--;
         spin_unlock(&fwc->name_lock);
@@ -1109,6 +1147,7 @@ static void dev_cache_fw_image(struct device *dev, void *data)
 
                 spin_lock(&fwc->name_lock);
                 fwc->cnt++;
+                list_add(&fce->list, &fwc->fw_names);
                 spin_unlock(&fwc->name_lock);
 
                 async_schedule(__async_dev_cache_fw_image, (void *)fce);
@@ -1164,7 +1203,10 @@ static void device_cache_fw_images(void)
         old_timeout = loading_timeout;
         loading_timeout = 10;
 
+        mutex_lock(&fw_lock);
+        fwc->state = FW_LOADER_START_CACHE;
         dpm_for_each_dev(NULL, dev_cache_fw_image);
+        mutex_unlock(&fw_lock);
 
         /* wait for completion of caching firmware for all devices */
         spin_lock(&fwc->name_lock);
@@ -1229,6 +1271,14 @@ static int fw_pm_notify(struct notifier_block *notify_block,
         case PM_POST_SUSPEND:
         case PM_POST_HIBERNATION:
         case PM_POST_RESTORE:
+                /*
+                 * In case that system sleep failed and syscore_suspend is
+                 * not called.
+                 */
+                mutex_lock(&fw_lock);
+                fw_cache.state = FW_LOADER_NO_CACHE;
+                mutex_unlock(&fw_lock);
+
                 device_uncache_fw_images_delay(10 * MSEC_PER_SEC);
                 break;
         }
@@ -1243,6 +1293,17 @@ static int fw_pm_notify(struct notifier_block *notify_block,
 }
 #endif
 
+/* stop caching firmware once syscore_suspend is reached */
+static int fw_suspend(void)
+{
+        fw_cache.state = FW_LOADER_NO_CACHE;
+        return 0;
+}
+
+static struct syscore_ops fw_syscore_ops = {
+        .suspend = fw_suspend,
+};
+
 static void __init fw_cache_init(void)
 {
         spin_lock_init(&fw_cache.lock);
@@ -1251,6 +1312,7 @@ static void __init fw_cache_init(void)
         spin_lock_init(&fw_cache.name_lock);
         INIT_LIST_HEAD(&fw_cache.fw_names);
         fw_cache.cnt = 0;
+        fw_cache.state = FW_LOADER_NO_CACHE;
 
         init_waitqueue_head(&fw_cache.wait_queue);
         INIT_DELAYED_WORK(&fw_cache.work,
@@ -1258,6 +1320,8 @@ static void __init fw_cache_init(void)
 
         fw_cache.pm_notify.notifier_call = fw_pm_notify;
         register_pm_notifier(&fw_cache.pm_notify);
+
+        register_syscore_ops(&fw_syscore_ops);
 }
 
 static int __init firmware_class_init(void)
@@ -1268,6 +1332,7 @@ static int __init firmware_class_init(void)
 
 static void __exit firmware_class_exit(void)
 {
+        unregister_syscore_ops(&fw_syscore_ops);
         unregister_pm_notifier(&fw_cache.pm_notify);
         class_unregister(&firmware_class);
 }