[PATCH 5.4 17/77] net: moxa: get rid of asymmetry in DMA mapping/unmapping

Greg Kroah-Hartman
2022-09-02T12:33:29Z

From: Sergei Antonov <saproj@gmail.com>

[ Upstream commit 0ee7828dfc56e97d71e51e6374dc7b4eb2b6e081 ]

Since priv->rx_mapping[i] is maped in moxart_mac_open(), we
should unmap it from moxart_mac_stop(). Fixes 2 warnings.

1. During error unwinding in moxart_mac_probe(): "goto init_fail;",
then moxart_mac_free_memory() calls dma_unmap_single() with
priv->rx_mapping[i] pointers zeroed.

WARNING: CPU: 0 PID: 1 at kernel/dma/debug.c:963 check_unmap+0x704/0x980
DMA-API: moxart-ethernet 92000000.mac: device driver tries to free DMA memory it has not allocated [device address=0x0000000000000000] [size=1600 bytes]
CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0+ #60
Hardware name: Generic DT based system
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x34/0x44
dump_stack_lvl from __warn+0xbc/0x1f0
__warn from warn_slowpath_fmt+0x94/0xc8
warn_slowpath_fmt from check_unmap+0x704/0x980
check_unmap from debug_dma_unmap_page+0x8c/0x9c
debug_dma_unmap_page from moxart_mac_free_memory+0x3c/0xa8
moxart_mac_free_memory from moxart_mac_probe+0x190/0x218
moxart_mac_probe from platform_probe+0x48/0x88
platform_probe from really_probe+0xc0/0x2e4

2. After commands:
ip link set dev eth0 down
ip link set dev eth0 up

WARNING: CPU: 0 PID: 55 at kernel/dma/debug.c:570 add_dma_entry+0x204/0x2ec
DMA-API: moxart-ethernet 92000000.mac: cacheline tracking EEXIST, overlapping mappings aren't supported
CPU: 0 PID: 55 Comm: ip Not tainted 5.19.0+ #57
Hardware name: Generic DT based system
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x34/0x44
dump_stack_lvl from __warn+0xbc/0x1f0
__warn from warn_slowpath_fmt+0x94/0xc8
warn_slowpath_fmt from add_dma_entry+0x204/0x2ec
add_dma_entry from dma_map_page_attrs+0x110/0x328
dma_map_page_attrs from moxart_mac_open+0x134/0x320
moxart_mac_open from __dev_open+0x11c/0x1ec
__dev_open from __dev_change_flags+0x194/0x22c
__dev_change_flags from dev_change_flags+0x14/0x44
dev_change_flags from devinet_ioctl+0x6d4/0x93c
devinet_ioctl from inet_ioctl+0x1ac/0x25c

v1 -> v2:
Extraneous change removed.

Fixes: 6c821bd9edc9 ("net: Add MOXA ART SoCs ethernet driver")
Signed-off-by: Sergei Antonov <saproj@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220819110519.1230877-1-saproj@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/moxa/moxart_ether.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c
index 383d72415c659..87327086ea8ca 100644
--- a/drivers/net/ethernet/moxa/moxart_ether.c
+++ b/drivers/net/ethernet/moxa/moxart_ether.c
@@ -74,11 +74,6 @@ static int moxart_set_mac_address(struct net_device *ndev, void *addr)
static void moxart_mac_free_memory(struct net_device *ndev)
{
struct moxart_mac_priv_t *priv = netdev_priv(ndev);
- int i;
-
- for (i = 0; i < RX_DESC_NUM; i++)
- dma_unmap_single(&priv->pdev->dev, priv->rx_mapping[i],
- priv->rx_buf_size, DMA_FROM_DEVICE);

if (priv->tx_desc_base)
dma_free_coherent(&priv->pdev->dev,
@@ -193,6 +188,7 @@ static int moxart_mac_open(struct net_device *ndev)
static int moxart_mac_stop(struct net_device *ndev)
{
struct moxart_mac_priv_t *priv = netdev_priv(ndev);
+ int i;

napi_disable(&priv->napi);

@@ -204,6 +200,11 @@ static int moxart_mac_stop(struct net_device *ndev)
/* disable all functions */
writel(0, priv->base + REG_MAC_CTRL);

+ /* unmap areas mapped in moxart_mac_setup_desc_ring() */
+ for (i = 0; i < RX_DESC_NUM; i++)
+ dma_unmap_single(&priv->pdev->dev, priv->rx_mapping[i],
+ priv->rx_buf_size, DMA_FROM_DEVICE);
+
return 0;
}

--
2.35.1