[PATCH 5.4 100/151] lan743x: fix "BUG: invalid wait context" when setting rx mode

[Greg Kroah-Hartman]

From: Sven Van Asbroeck <thesve...@gmail.com>

[ Upstream commit 2b52a4b65bc8f14520fe6e996ea7fb3f7e400761 ]

In the net core, the struct net_device_ops -> ndo_set_rx_mode()
callback is called with the dev->addr_list_lock spinlock held.

However, this driver's ndo_set_rx_mode callback eventually calls
lan743x_dp_write(), which acquires a mutex. Mutex acquisition
may sleep, and this is not allowed when holding a spinlock.

Fix by removing the dp_lock mutex entirely. Its purpose is to
prevent concurrent accesses to the data port. No concurrent
accesses are possible, because the dev->addr_list_lock
spinlock in the core only lets through one thread at a time.

Fixes: 23f0703c125b ("lan743x: Add main source files for new lan743x driver")
Signed-off-by: Sven Van Asbroeck <thesve...@gmail.com>
Link: https://lore.kernel.org/r/20201109203828.5115-1-thesve...@gmail.com
Signed-off-by: Jakub Kicinski <k...@kernel.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/net/ethernet/microchip/lan743x_main.c | 12 +++---------
 drivers/net/ethernet/microchip/lan743x_main.h |  3 ---
 2 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c 
b/drivers/net/ethernet/microchip/lan743x_main.c
index a43140f7b5eb8..b8e0e08b79de2 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -672,14 +672,12 @@ clean_up:
 static int lan743x_dp_write(struct lan743x_adapter *adapter,
                            u32 select, u32 addr, u32 length, u32 *buf)
 {
-       int ret = -EIO;
        u32 dp_sel;
        int i;
 
-       mutex_lock(&adapter->dp_lock);
        if (lan743x_csr_wait_for_bit(adapter, DP_SEL, DP_SEL_DPRDY_,
                                     1, 40, 100, 100))
-               goto unlock;
+               return -EIO;
        dp_sel = lan743x_csr_read(adapter, DP_SEL);
        dp_sel &= ~DP_SEL_MASK_;
        dp_sel |= select;
@@ -691,13 +689,10 @@ static int lan743x_dp_write(struct lan743x_adapter 
*adapter,
                lan743x_csr_write(adapter, DP_CMD, DP_CMD_WRITE_);
                if (lan743x_csr_wait_for_bit(adapter, DP_SEL, DP_SEL_DPRDY_,
                                             1, 40, 100, 100))
-                       goto unlock;
+                       return -EIO;
        }
-       ret = 0;
 
-unlock:
-       mutex_unlock(&adapter->dp_lock);
-       return ret;
+       return 0;
 }
 
 static u32 lan743x_mac_mii_access(u16 id, u16 index, int read)
@@ -2674,7 +2669,6 @@ static int lan743x_hardware_init(struct lan743x_adapter 
*adapter,
 
        adapter->intr.irq = adapter->pdev->irq;
        lan743x_csr_write(adapter, INT_EN_CLR, 0xFFFFFFFF);
-       mutex_init(&adapter->dp_lock);
 
        ret = lan743x_gpio_init(adapter);
        if (ret)
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h 
b/drivers/net/ethernet/microchip/lan743x_main.h
index 3b02eeae5f45d..1fbcef3910989 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -706,9 +706,6 @@ struct lan743x_adapter {
        struct lan743x_csr      csr;
        struct lan743x_intr     intr;
 
-       /* lock, used to prevent concurrent access to data port */
-       struct mutex            dp_lock;
-
        struct lan743x_gpio     gpio;
        struct lan743x_ptp      ptp;
 
-- 
2.27.0