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From: Marek Vasut <marex@denx.de>
To: linux-i2c@vger.kernel.org
Cc: Marek Vasut <marex@denx.de>,
	Michal Simek <michal.simek@xilinx.com>,
	Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>,
	Wolfram Sang <wsa@kernel.org>
Subject: [PATCH v2 1/6] i2c: xiic: Fix broken locking on tx_msg
Date: Mon, 23 Aug 2021 23:41:40 +0200	[thread overview]
Message-ID: <20210823214145.295104-2-marex@denx.de> (raw)
In-Reply-To: <20210823214145.295104-1-marex@denx.de>

The tx_msg is set from multiple places, sometimes without locking,
which fall apart on any SMP system. Only ever access tx_msg inside
the driver mutex.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Cc: Wolfram Sang <wsa@kernel.org>
---
V2: Initialize RX message pointer in xiic_start_xfer() too
---
 drivers/i2c/busses/i2c-xiic.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index bb93db98404ef..50320dd32eea9 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -170,7 +170,7 @@ struct xiic_i2c {
 #define xiic_tx_space(i2c) ((i2c)->tx_msg->len - (i2c)->tx_pos)
 #define xiic_rx_space(i2c) ((i2c)->rx_msg->len - (i2c)->rx_pos)
 
-static int xiic_start_xfer(struct xiic_i2c *i2c);
+static int xiic_start_xfer(struct xiic_i2c *i2c, struct i2c_msg *msgs, int num);
 static void __xiic_start_xfer(struct xiic_i2c *i2c);
 
 /*
@@ -684,15 +684,25 @@ static void __xiic_start_xfer(struct xiic_i2c *i2c)
 
 }
 
-static int xiic_start_xfer(struct xiic_i2c *i2c)
+static int xiic_start_xfer(struct xiic_i2c *i2c, struct i2c_msg *msgs, int num)
 {
 	int ret;
+
 	mutex_lock(&i2c->lock);
 
+	ret = xiic_busy(i2c);
+	if (ret)
+		goto out;
+
+	i2c->tx_msg = msgs;
+	i2c->rx_msg = NULL;
+	i2c->nmsgs = num;
+
 	ret = xiic_reinit(i2c);
 	if (!ret)
 		__xiic_start_xfer(i2c);
 
+out:
 	mutex_unlock(&i2c->lock);
 
 	return ret;
@@ -710,14 +720,7 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	if (err < 0)
 		return err;
 
-	err = xiic_busy(i2c);
-	if (err)
-		goto out;
-
-	i2c->tx_msg = msgs;
-	i2c->nmsgs = num;
-
-	err = xiic_start_xfer(i2c);
+	err = xiic_start_xfer(i2c, msgs, num);
 	if (err < 0) {
 		dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
 		goto out;
@@ -725,9 +728,11 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 
 	if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
 		(i2c->state == STATE_DONE), HZ)) {
+		mutex_lock(&i2c->lock);
 		err = (i2c->state == STATE_DONE) ? num : -EIO;
 		goto out;
 	} else {
+		mutex_lock(&i2c->lock);
 		i2c->tx_msg = NULL;
 		i2c->rx_msg = NULL;
 		i2c->nmsgs = 0;
@@ -735,6 +740,7 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 		goto out;
 	}
 out:
+	mutex_unlock(&i2c->lock);
 	pm_runtime_mark_last_busy(i2c->dev);
 	pm_runtime_put_autosuspend(i2c->dev);
 	return err;
-- 
2.32.0


  reply	other threads:[~2021-08-23 21:42 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 21:41 [PATCH v2 0/6] i2c: xiic: Fix broken locking Marek Vasut
2021-08-23 21:41 ` Marek Vasut [this message]
2021-08-23 21:41 ` [PATCH v2 2/6] i2c: xiic: Drop broken interrupt handler Marek Vasut
2021-08-23 21:41 ` [PATCH v2 3/6] i2c: xiic: Defer xiic_wakeup() and __xiic_start_xfer() in xiic_process() Marek Vasut
2021-08-23 21:41 ` [PATCH v2 4/6] i2c: xiic: Switch from waitqueue to completion Marek Vasut
2021-08-23 21:41 ` [PATCH v2 5/6] i2c: xiic: Only ever transfer single message Marek Vasut
2021-08-23 21:41 ` [PATCH v2 6/6] i2c: xiic: Fix RX IRQ busy check Marek Vasut
2021-08-24  6:58 ` [PATCH v2 0/6] i2c: xiic: Fix broken locking Michal Simek
2021-08-27  8:31   ` Raviteja Narayanam
2021-08-27  8:34     ` Michal Simek
2021-09-14 10:29 ` Wolfram Sang
2021-09-14 11:54   ` Michal Simek

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