[PATCH] i3c: master: dw: fix deadlock

Jisheng Zhang
2019-01-25T07:42:05Z

In dw_i3c_master_irq_handler(), we already have gotten
&master->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 &master->xferqueue.lock.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
drivers/i3c/master/dw-i3c-master.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
index f8c00b94817f..bb03079fbade 100644
--- 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);
}
--
2.20.1

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