The carrier_lock spinlock protects the carrier detection. While it is
hold, framer_get_status() is called witch in turn takes a mutex.
This is not correct and can lead to a deadlock.
A run with PROVE_LOCKING enabled detected the issue:
[ BUG: Invalid wait context ]
...
c204ddbc (&framer->mutex){+.+.}-{3:3}, at: framer_get_status+0x40/0x78
other info that might help us debug this:
context-{4:4}
2 locks held by ifconfig/146:
#0: c0926a38 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x12c/0x664
#1: c2006a40 (&qmc_hdlc->carrier_lock){....}-{2:2}, at: qmc_hdlc_framer_set_carrier+0x30/0x98
Avoid the spinlock usage and convert carrier_lock to a mutex.
Fixes: 54762918ca85 ("net: wan: fsl_qmc_hdlc: Add framer support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
---
drivers/net/wan/fsl_qmc_hdlc.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/net/wan/fsl_qmc_hdlc.c b/drivers/net/wan/fsl_qmc_hdlc.c
index c5e7ca793c43..64b4bfa6fea7 100644
--- a/drivers/net/wan/fsl_qmc_hdlc.c
+++ b/drivers/net/wan/fsl_qmc_hdlc.c
@@ -18,6 +18,7 @@
#include <linux/hdlc.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
@@ -37,7 +38,7 @@ struct qmc_hdlc {
struct qmc_chan *qmc_chan;
struct net_device *netdev;
struct framer *framer;
- spinlock_t carrier_lock; /* Protect carrier detection */
+ struct mutex carrier_lock; /* Protect carrier detection */
struct notifier_block nb;
bool is_crc32;
spinlock_t tx_lock; /* Protect tx descriptors */
@@ -60,7 +61,7 @@ static int qmc_hdlc_framer_set_carrier(struct qmc_hdlc *qmc_hdlc)
if (!qmc_hdlc->framer)
return 0;
- guard(spinlock_irqsave)(&qmc_hdlc->carrier_lock);
+ guard(mutex)(&qmc_hdlc->carrier_lock);
ret = framer_get_status(qmc_hdlc->framer, &framer_status);
if (ret) {
@@ -706,7 +707,7 @@ static int qmc_hdlc_probe(struct platform_device *pdev)
qmc_hdlc->dev = dev;
spin_lock_init(&qmc_hdlc->tx_lock);
- spin_lock_init(&qmc_hdlc->carrier_lock);
+ mutex_init(&qmc_hdlc->carrier_lock);
qmc_hdlc->qmc_chan = devm_qmc_chan_get_bychild(dev, dev->of_node);
if (IS_ERR(qmc_hdlc->qmc_chan))
--
2.45.0
