--- /dev/null
+From f007cad159e99fa2acd3b2e9364fbb32ad28b971 Mon Sep 17 00:00:00 2001
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sun, 10 Sep 2017 21:19:06 -0700
+Subject: Revert "firmware: add sanity check on shutdown/suspend"
+
+From: Linus Torvalds <torvalds@linux-foundation.org>
+
+commit f007cad159e99fa2acd3b2e9364fbb32ad28b971 upstream.
+
+This reverts commit 81f95076281fdd3bc382e004ba1bce8e82fccbce.
+
+It causes random failures of firmware loading at resume time (well,
+random for me, it seems to be more reliable for others) because the
+firmware disabling is not actually synchronous with any particular
+resume event, and at least the btusb driver that uses a workqueue to
+load the firmware at resume seems to occasionally hit the "firmware
+loading is disabled" logic because the firmware loader hasn't gotten the
+resume event yet.
+
+Some kind of sanity check for not trying to load firmware when it's not
+possible might be a good thing, but this commit was not it.
+
+Greg seems to have silently suffered the same issue, and pointed to the
+likely culprit, and Gabriel C verified the revert fixed it for him too.
+
+Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
+Pointed-at-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Tested-by: Gabriel C <nix.or.die@gmail.com>
+Cc: Luis R. Rodriguez <mcgrof@kernel.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ Documentation/driver-api/firmware/request_firmware.rst | 11 -
+ drivers/base/firmware_class.c | 99 -----------------
+ 2 files changed, 110 deletions(-)
+
+--- a/Documentation/driver-api/firmware/request_firmware.rst
++++ b/Documentation/driver-api/firmware/request_firmware.rst
+@@ -44,17 +44,6 @@ request_firmware_nowait
+ .. kernel-doc:: drivers/base/firmware_class.c
+ :functions: request_firmware_nowait
+
+-Considerations for suspend and resume
+-=====================================
+-
+-During suspend and resume only the built-in firmware and the firmware cache
+-elements of the firmware API can be used. This is managed by fw_pm_notify().
+-
+-fw_pm_notify
+-------------
+-.. kernel-doc:: drivers/base/firmware_class.c
+- :functions: fw_pm_notify
+-
+ request firmware API expected driver use
+ ========================================
+
+--- a/drivers/base/firmware_class.c
++++ b/drivers/base/firmware_class.c
+@@ -256,38 +256,6 @@ static int fw_cache_piggyback_on_request
+ * guarding for corner cases a global lock should be OK */
+ static DEFINE_MUTEX(fw_lock);
+
+-static bool __enable_firmware = false;
+-
+-static void enable_firmware(void)
+-{
+- mutex_lock(&fw_lock);
+- __enable_firmware = true;
+- mutex_unlock(&fw_lock);
+-}
+-
+-static void disable_firmware(void)
+-{
+- mutex_lock(&fw_lock);
+- __enable_firmware = false;
+- mutex_unlock(&fw_lock);
+-}
+-
+-/*
+- * When disabled only the built-in firmware and the firmware cache will be
+- * used to look for firmware.
+- */
+-static bool firmware_enabled(void)
+-{
+- bool enabled = false;
+-
+- mutex_lock(&fw_lock);
+- if (__enable_firmware)
+- enabled = true;
+- mutex_unlock(&fw_lock);
+-
+- return enabled;
+-}
+-
+ static struct firmware_cache fw_cache;
+
+ static struct firmware_buf *__allocate_fw_buf(const char *fw_name,
+@@ -1239,12 +1207,6 @@ _request_firmware(const struct firmware
+ if (ret <= 0) /* error or already assigned */
+ goto out;
+
+- if (!firmware_enabled()) {
+- WARN(1, "firmware request while host is not available\n");
+- ret = -EHOSTDOWN;
+- goto out;
+- }
+-
+ ret = fw_get_filesystem_firmware(device, fw->priv);
+ if (ret) {
+ if (!(opt_flags & FW_OPT_NO_WARN))
+@@ -1755,62 +1717,6 @@ static void device_uncache_fw_images_del
+ msecs_to_jiffies(delay));
+ }
+
+-/**
+- * fw_pm_notify - notifier for suspend/resume
+- * @notify_block: unused
+- * @mode: mode we are switching to
+- * @unused: unused
+- *
+- * Used to modify the firmware_class state as we move in between states.
+- * The firmware_class implements a firmware cache to enable device driver
+- * to fetch firmware upon resume before the root filesystem is ready. We
+- * disable API calls which do not use the built-in firmware or the firmware
+- * cache when we know these calls will not work.
+- *
+- * The inner logic behind all this is a bit complex so it is worth summarizing
+- * the kernel's own suspend/resume process with context and focus on how this
+- * can impact the firmware API.
+- *
+- * First a review on how we go to suspend::
+- *
+- * pm_suspend() --> enter_state() -->
+- * sys_sync()
+- * suspend_prepare() -->
+- * __pm_notifier_call_chain(PM_SUSPEND_PREPARE, ...);
+- * suspend_freeze_processes() -->
+- * freeze_processes() -->
+- * __usermodehelper_set_disable_depth(UMH_DISABLED);
+- * freeze all tasks ...
+- * freeze_kernel_threads()
+- * suspend_devices_and_enter() -->
+- * dpm_suspend_start() -->
+- * dpm_prepare()
+- * dpm_suspend()
+- * suspend_enter() -->
+- * platform_suspend_prepare()
+- * dpm_suspend_late()
+- * freeze_enter()
+- * syscore_suspend()
+- *
+- * When we resume we bail out of a loop from suspend_devices_and_enter() and
+- * unwind back out to the caller enter_state() where we were before as follows::
+- *
+- * enter_state() -->
+- * suspend_devices_and_enter() --> (bail from loop)
+- * dpm_resume_end() -->
+- * dpm_resume()
+- * dpm_complete()
+- * suspend_finish() -->
+- * suspend_thaw_processes() -->
+- * thaw_processes() -->
+- * __usermodehelper_set_disable_depth(UMH_FREEZING);
+- * thaw_workqueues();
+- * thaw all processes ...
+- * usermodehelper_enable();
+- * pm_notifier_call_chain(PM_POST_SUSPEND);
+- *
+- * fw_pm_notify() works through pm_notifier_call_chain().
+- */
+ static int fw_pm_notify(struct notifier_block *notify_block,
+ unsigned long mode, void *unused)
+ {
+@@ -1824,7 +1730,6 @@ static int fw_pm_notify(struct notifier_
+ */
+ kill_pending_fw_fallback_reqs(true);
+ device_cache_fw_images();
+- disable_firmware();
+ break;
+
+ case PM_POST_SUSPEND:
+@@ -1837,7 +1742,6 @@ static int fw_pm_notify(struct notifier_
+ mutex_lock(&fw_lock);
+ fw_cache.state = FW_LOADER_NO_CACHE;
+ mutex_unlock(&fw_lock);
+- enable_firmware();
+
+ device_uncache_fw_images_delay(10 * MSEC_PER_SEC);
+ break;
+@@ -1886,7 +1790,6 @@ static void __init fw_cache_init(void)
+ static int fw_shutdown_notify(struct notifier_block *unused1,
+ unsigned long unused2, void *unused3)
+ {
+- disable_firmware();
+ /*
+ * Kill all pending fallback requests to avoid both stalling shutdown,
+ * and avoid a deadlock with the usermode_lock.
+@@ -1902,7 +1805,6 @@ static struct notifier_block fw_shutdown
+
+ static int __init firmware_class_init(void)
+ {
+- enable_firmware();
+ fw_cache_init();
+ register_reboot_notifier(&fw_shutdown_nb);
+ #ifdef CONFIG_FW_LOADER_USER_HELPER
+@@ -1914,7 +1816,6 @@ static int __init firmware_class_init(vo
+
+ static void __exit firmware_class_exit(void)
+ {
+- disable_firmware();
+ #ifdef CONFIG_PM_SLEEP
+ unregister_syscore_ops(&fw_syscore_ops);
+ unregister_pm_notifier(&fw_cache.pm_notify);
projects / thirdparty / kernel / stable-queue.git / commitdiff
