[PATCH net v2] net: wireless: marvell: mwifiex: fix sleep in atomic context bugs

[Duoming Zhou]

There are sleep in atomic context bugs when uploading device dump
data on usb interface. The root cause is that the operations that
may sleep are called in fw_dump_timer_fn which is a timer handler.
The call tree shows the execution paths that could lead to bugs:

   (Interrupt context)
fw_dump_timer_fn
  mwifiex_upload_device_dump
    dev_coredumpv(..., GFP_KERNEL)
      dev_coredumpm()
        kzalloc(sizeof(*devcd), gfp); //may sleep
        dev_set_name
          kobject_set_name_vargs
            kvasprintf_const(GFP_KERNEL, ...); //may sleep
            kstrdup(s, GFP_KERNEL); //may sleep

This patch moves the operations that may sleep into a work item.
The work item will run in another kernel thread which is in
process context to execute the bottom half of the interrupt.
So it could prevent atomic context from sleeping.

Fixes: f5ecd02a8b20 ("mwifiex: device dump support for usb interface")
Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
---
Changes in v2:
  - Fix compile problem.

 drivers/net/wireless/marvell/mwifiex/init.c      | 12 +++++++++++-
 drivers/net/wireless/marvell/mwifiex/main.h      |  1 +
 drivers/net/wireless/marvell/mwifiex/sta_event.c |  1 +
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/init.c b/drivers/net/wireless/marvell/mwifiex/init.c
index 88c72d1827a..cc3f1121eb9 100644
--- a/drivers/net/wireless/marvell/mwifiex/init.c
+++ b/drivers/net/wireless/marvell/mwifiex/init.c
@@ -63,11 +63,19 @@ static void wakeup_timer_fn(struct timer_list *t)
 		adapter->if_ops.card_reset(adapter);
 }
 
+static void fw_dump_work(struct work_struct *work)
+{
+	struct mwifiex_adapter *adapter =
+		container_of(work, struct mwifiex_adapter, devdump_work);
+
+	mwifiex_upload_device_dump(adapter);
+}
+
 static void fw_dump_timer_fn(struct timer_list *t)
 {
 	struct mwifiex_adapter *adapter = from_timer(adapter, t, devdump_timer);
 
-	mwifiex_upload_device_dump(adapter);
+	schedule_work(&adapter->devdump_work);
 }
 
 /*
@@ -321,6 +329,7 @@ static void mwifiex_init_adapter(struct mwifiex_adapter *adapter)
 	adapter->active_scan_triggered = false;
 	timer_setup(&adapter->wakeup_timer, wakeup_timer_fn, 0);
 	adapter->devdump_len = 0;
+	INIT_WORK(&adapter->devdump_work, fw_dump_work);
 	timer_setup(&adapter->devdump_timer, fw_dump_timer_fn, 0);
 }
 
@@ -401,6 +410,7 @@ mwifiex_adapter_cleanup(struct mwifiex_adapter *adapter)
 {
 	del_timer(&adapter->wakeup_timer);
 	del_timer_sync(&adapter->devdump_timer);
+	cancel_work_sync(&adapter->devdump_work);
 	mwifiex_cancel_all_pending_cmd(adapter);
 	wake_up_interruptible(&adapter->cmd_wait_q.wait);
 	wake_up_interruptible(&adapter->hs_activate_wait_q);
diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
index 332dd1c8db3..c8ac2f57f18 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.h
+++ b/drivers/net/wireless/marvell/mwifiex/main.h
@@ -900,6 +900,7 @@ struct mwifiex_adapter {
 	struct work_struct rx_work;
 	struct workqueue_struct *dfs_workqueue;
 	struct work_struct dfs_work;
+	struct work_struct devdump_work;
 	bool rx_work_enabled;
 	bool rx_processing;
 	bool delay_main_work;
diff --git a/drivers/net/wireless/marvell/mwifiex/sta_event.c b/drivers/net/wireless/marvell/mwifiex/sta_event.c
index 7d42c5d2dbf..8e28d0107d7 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_event.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_event.c
@@ -644,6 +644,7 @@ mwifiex_fw_dump_info_event(struct mwifiex_private *priv,
 
 upload_dump:
 	del_timer_sync(&adapter->devdump_timer);
+	cancel_work_sync(&adapter->devdump_work);
 	mwifiex_upload_device_dump(adapter);
 }
 
-- 
2.17.1