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Commit 6eeaf72f authored by Subash Abhinov Kasiviswanathan's avatar Subash Abhinov Kasiviswanathan
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soc: qcom: dfc: Fix potential data stall 



The worker thread callback can potentially fail to acquire
the trylock(). In such a case, retry to acquire the lock to avoid
dropping any flow enable messages which would result in a stall.

Usually multiple flow control messages with flow enable are sent
so this scenario could likely never occur.

CRs-Fixed: 2285862
Change-Id: Ic92d811c65e48829bcad26f3b8b6b720d16c6c1e
Signed-off-by: default avatarSubash Abhinov Kasiviswanathan <subashab@codeaurora.org>
parent 130b5c4c

drivers/soc/qcom/dfc_qmi.c

+17 −4
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ struct dfc_qmi_data { 
	struct qmi_handle handle;

	struct sockaddr_qrtr ssctl;

	int index;

	int restart_state;

};



struct dfc_svc_ind {
@@ -605,6 +606,7 @@ static void dfc_do_burst_flow_control(struct work_struct *work) 
		return;

	}



get_lock:

	local_bh_disable();

	/* This will drop some messages but that is

	 * unavoidable for now since the notifier callback is
@@ -612,11 +614,20 @@ static void dfc_do_burst_flow_control(struct work_struct *work) 
	 * will dead lock with this.

	 */

	if (!rtnl_trylock()) {

		if (!svc_ind->data->restart_state) {

			local_bh_enable();

			msleep(20);

			goto get_lock;

		} else {

			kfree(ind);

			kfree(svc_ind);

			local_bh_enable();

			return;

		}

	}



	if (unlikely(svc_ind->data->restart_state))

		goto clean_out;



	for (i = 0; i < ind->flow_status_len; i++) {

		flow_status = &ind->flow_status[i];
@@ -767,6 +778,7 @@ int dfc_qmi_client_init(void *port, int index, struct qmi_info *qmi) 


	data->rmnet_port = port;

	data->index = index;

	data->restart_state = 0;



	data->dfc_wq = create_singlethread_workqueue("dfc_wq");

	if (!data->dfc_wq) {
@@ -811,6 +823,7 @@ void dfc_qmi_client_exit(void *dfc_data) 
		return;

	}



	data->restart_state = 1;

	trace_dfc_client_state_down(data->index, 0);

	qmi_handle_release(&data->handle);