i3c: master: dw: fix deadlock

Jisheng Zhang · bbrezillon · commit f36c1f9a8dfd · 2019-01-26T11:14:25.000+01:00
In dw_i3c_master_irq_handler(), we already have gotten
&amp;master-&gt;xferqueue.lock, if we try to get the same lock again in
dw_i3c_master_dequeue_xfer(), deadlock happens.

We fix this issue by introduing dw_i3c_master_dequeue_xfer_locked()
which does all what dw_i3c_master_dequeue_xfer() does without trying
to lock &amp;master-&gt;xferqueue.lock.

Signed-off-by: Jisheng Zhang &lt;Jisheng.Zhang@synaptics.com&gt;
Acked-by: Vitor Soares &lt;vitor.soares@synopsys.com&gt;
Signed-off-by: Boris Brezillon &lt;bbrezillon@kernel.org&gt;
diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
@@ -419,12 +419,9 @@ static void dw_i3c_master_enqueue_xfer(struct dw_i3c_master *master,
 	spin_unlock_irqrestore(&master->xferqueue.lock, flags);
 }
 
-static void dw_i3c_master_dequeue_xfer(struct dw_i3c_master *master,
-				       struct dw_i3c_xfer *xfer)
+static void dw_i3c_master_dequeue_xfer_locked(struct dw_i3c_master *master,
+					      struct dw_i3c_xfer *xfer)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&master->xferqueue.lock, flags);
 	if (master->xferqueue.cur == xfer) {
 		u32 status;
 
@@ -439,6 +436,15 @@ static void dw_i3c_master_dequeue_xfer(struct dw_i3c_master *master,
 	} else {
 		list_del_init(&xfer->node);
 	}
+}
+
+static void dw_i3c_master_dequeue_xfer(struct dw_i3c_master *master,
+				       struct dw_i3c_xfer *xfer)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&master->xferqueue.lock, flags);
+	dw_i3c_master_dequeue_xfer_locked(master, xfer);
 	spin_unlock_irqrestore(&master->xferqueue.lock, flags);
 }
 
@@ -494,7 +500,7 @@ static void dw_i3c_master_end_xfer_locked(struct dw_i3c_master *master, u32 isr)
 	complete(&xfer->comp);
 
 	if (ret < 0) {
-		dw_i3c_master_dequeue_xfer(master, xfer);
+		dw_i3c_master_dequeue_xfer_locked(master, xfer);
 		writel(readl(master->regs + DEVICE_CTRL) | DEV_CTRL_RESUME,
 		       master->regs + DEVICE_CTRL);
 	}
