linux-kernel - [PATCH] firmware_loader: Add reboot_in

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Date:   Fri, 15 Sep 2023 15:51:28 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     <mcgrof@...nel.org>, <russell.h.weight@...el.com>,
        <gregkh@...uxfoundation.org>, <rafael@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        Mukesh Ojha <quic_mojha@...cinc.com>
Subject: [PATCH] firmware_loader: Add reboot_in_progress for user helper path

There could be following scenario where there is a ongoing reboot
is going from processA which tries to call all the reboot notifier
callback and one of them is firmware reboot call which tries to
abort all the ongoing firmware userspace request under fw_lock
but there could be another processB which tries to do request
firmware, which came just after abort done from ProcessA and
ask for userspace to load the firmware and this can stop the
ongoing reboot ProcessA to stall for next 60s(default timeout)
which may be expected behaviour everyone like to see, instead
we should abort every request which came after once firmware
marks reboot notification.

      ProcessA                             ProcessB

kernel_restart_prepare
  blocking_notifier_call_chain
   fw_shutdown_notify
     kill_pending_fw_fallback_reqs
      __fw_load_abort
       fw_state_aborted	              request_firmware
         __fw_state_set                   firmware_fallback_sysfs
...                                        fw_load_from_user_helper
..                                         ...
.                                          ..
                                            usermodehelper_read_trylock
                                             fw_load_sysfs_fallback
                                              fw_sysfs_wait_timeout
usermodehelper_disable
 __usermodehelper_disable
  down_write()

Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
---
 drivers/base/firmware_loader/fallback.c | 2 +-
 drivers/base/firmware_loader/firmware.h | 1 +
 drivers/base/firmware_loader/main.c     | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index bf68e3947814..a5546aeea91f 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -86,7 +86,7 @@ static int fw_load_sysfs_fallback(struct fw_sysfs *fw_sysfs, long timeout)
 	}
 
 	mutex_lock(&fw_lock);
-	if (fw_state_is_aborted(fw_priv)) {
+	if (reboot_in_progress || fw_state_is_aborted(fw_priv)) {
 		mutex_unlock(&fw_lock);
 		retval = -EINTR;
 		goto out;
diff --git a/drivers/base/firmware_loader/firmware.h b/drivers/base/firmware_loader/firmware.h
index bf549d6500d7..6f44248e2e44 100644
--- a/drivers/base/firmware_loader/firmware.h
+++ b/drivers/base/firmware_loader/firmware.h
@@ -86,6 +86,7 @@ struct fw_priv {
 
 extern struct mutex fw_lock;
 extern struct firmware_cache fw_cache;
+extern bool reboot_in_progress;
 
 static inline bool __fw_state_check(struct fw_priv *fw_priv,
 				    enum fw_status status)
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index b58c42f1b1ce..d72b7950edf0 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -93,6 +93,7 @@ static inline struct fw_priv *to_fw_priv(struct kref *ref)
 DEFINE_MUTEX(fw_lock);
 
 struct firmware_cache fw_cache;
+bool reboot_in_progress;
 
 void fw_state_init(struct fw_priv *fw_priv)
 {
@@ -1613,6 +1614,7 @@ static int fw_shutdown_notify(struct notifier_block *unused1,
 	 * and avoid a deadlock with the usermode_lock.
 	 */
 	kill_pending_fw_fallback_reqs(false);
+	reboot_in_progress = true;
 
 	return NOTIFY_DONE;
 }
-- 
2.7.4