| Message ID | 20220818182948.931712-2-saproj@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [1/2] net: moxa: do not call dma_unmap_single() with null | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Thu, Aug 18, 2022 at 09:29:48PM +0300, Sergei Antonov wrote: > Fix the warning poping up after bringing the link down, then up: > 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 > > Unmap RX memory areas in moxart_mac_stop(), so that moxart_mac_open() > will map them anew instead of double-mapping. To avoid code duplication, > create a new function moxart_mac_unmap_rx(). Nullify unmapped pointers to > prevent double-unmapping (ex: moxart_mac_stop(), then moxart_remove()). This makes the code symmetric, which is good. However, moxart_mac_free_memory() will also free the descriptors, which is not required. moxart_remove() should undo what the probe did, nothing more. Andrew
On Thu, 18 Aug 2022 at 22:27, Andrew Lunn <andrew@lunn.ch> wrote: > > Unmap RX memory areas in moxart_mac_stop(), so that moxart_mac_open() > > will map them anew instead of double-mapping. To avoid code duplication, > > create a new function moxart_mac_unmap_rx(). Nullify unmapped pointers to > > prevent double-unmapping (ex: moxart_mac_stop(), then moxart_remove()). > > This makes the code symmetric, which is good. > > However, moxart_mac_free_memory() will also free the descriptors, > which is not required. moxart_remove() should undo what the probe did, > nothing more. Having considered your comments, I now think I should make another patch, which fixes two problems at once. To unmap DMA areas only in moxart_mac_stop() and not in moxart_remove(). It will fix error unwinding during probe and double-mapping on link down, link up. It will be correct if Linux always calls moxart_mac_stop() before calling moxart_remove().
On Fri, Aug 19, 2022 at 11:12:11AM +0300, Sergei Antonov wrote: > On Thu, 18 Aug 2022 at 22:27, Andrew Lunn <andrew@lunn.ch> wrote: > > > Unmap RX memory areas in moxart_mac_stop(), so that moxart_mac_open() > > > will map them anew instead of double-mapping. To avoid code duplication, > > > create a new function moxart_mac_unmap_rx(). Nullify unmapped pointers to > > > prevent double-unmapping (ex: moxart_mac_stop(), then moxart_remove()). > > > > This makes the code symmetric, which is good. > > > > However, moxart_mac_free_memory() will also free the descriptors, > > which is not required. moxart_remove() should undo what the probe did, > > nothing more. > > Having considered your comments, I now think I should make another > patch, which fixes two problems at once. To unmap DMA areas only in > moxart_mac_stop() and not in moxart_remove(). It will fix error > unwinding during probe and double-mapping on link down, link up. It > will be correct if Linux always calls moxart_mac_stop() before calling > moxart_remove(). The way this is supposed to work is that from moxart_remove() you call unregister_netdev(), and this calls dev_close[_many]() internally. The dev_close() method calls your ndo_stop callback.
diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c index edd1dab2ec43..22d0bf4a21e7 100644 --- a/drivers/net/ethernet/moxa/moxart_ether.c +++ b/drivers/net/ethernet/moxa/moxart_ether.c @@ -71,15 +71,23 @@ static int moxart_set_mac_address(struct net_device *ndev, void *addr) return 0; } -static void moxart_mac_free_memory(struct net_device *ndev) +static void moxart_mac_unmap_rx(struct moxart_mac_priv_t *priv) { - struct moxart_mac_priv_t *priv = netdev_priv(ndev); int i; for (i = 0; i < RX_DESC_NUM; i++) - if (priv->rx_mapping[i]) + if (priv->rx_mapping[i]) { dma_unmap_single(&priv->pdev->dev, priv->rx_mapping[i], priv->rx_buf_size, DMA_FROM_DEVICE); + priv->rx_mapping[i] = 0; + } +} + +static void moxart_mac_free_memory(struct net_device *ndev) +{ + struct moxart_mac_priv_t *priv = netdev_priv(ndev); + + moxart_mac_unmap_rx(priv); if (priv->tx_desc_base) dma_free_coherent(&priv->pdev->dev, @@ -205,6 +213,7 @@ static int moxart_mac_stop(struct net_device *ndev) /* disable all functions */ writel(0, priv->base + REG_MAC_CTRL); + moxart_mac_unmap_rx(priv); return 0; }
Fix the warning poping up after bringing the link down, then up: 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 Unmap RX memory areas in moxart_mac_stop(), so that moxart_mac_open() will map them anew instead of double-mapping. To avoid code duplication, create a new function moxart_mac_unmap_rx(). Nullify unmapped pointers to prevent double-unmapping (ex: moxart_mac_stop(), then moxart_remove()). Fixes: 6c821bd9edc9 ("net: Add MOXA ART SoCs ethernet driver") Signed-off-by: Sergei Antonov <saproj@gmail.com> --- drivers/net/ethernet/moxa/moxart_ether.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)