net: mana: Improve mana_set_channels() in low mem conditions

The mana_set_channels() function requires detaching the mana
driver and reattaching it with changed channel values.
During this operation if the system is low on memory, the reattach
might fail, causing the network device being down.
To avoid this we pre-allocate buffers at the beginning of set operation,
to prevent complete network loss

Signed-off-by: Shradha Gupta <shradhagupta@linux.microsoft.com>
Reviewed-by: Gerhard Engleder <gerhard@engleder-embedded.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/1725248734-21760-1-git-send-email-shradhagupta@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index 3e865985340ed1985d4ed85e42a43d83c78ca25b..a174ca719aba5ae3b01f04a26972ec7cf868c1ae 100644 (file)
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -608,7 +608,7 @@ static void mana_get_rxbuf_cfg(int mtu, u32 *datasize, u32 *alloc_size,
        *datasize = mtu + ETH_HLEN;
 }
 
-int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu)
+int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu, int num_queues)
 {
        struct device *dev;
        struct page *page;
@@ -622,7 +622,7 @@ int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu)
 
        dev = mpc->ac->gdma_dev->gdma_context->dev;
 
-       num_rxb = mpc->num_queues * mpc->rx_queue_size;
+       num_rxb = num_queues * mpc->rx_queue_size;
 
        WARN(mpc->rxbufs_pre, "mana rxbufs_pre exists\n");
        mpc->rxbufs_pre = kmalloc_array(num_rxb, sizeof(void *), GFP_KERNEL);
@@ -682,7 +682,7 @@ static int mana_change_mtu(struct net_device *ndev, int new_mtu)
        int err;
 
        /* Pre-allocate buffers to prevent failure in mana_attach later */
-       err = mana_pre_alloc_rxbufs(mpc, new_mtu);
+       err = mana_pre_alloc_rxbufs(mpc, new_mtu, mpc->num_queues);
        if (err) {
                netdev_err(ndev, "Insufficient memory for new MTU\n");
                return err;

diff --git a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
index d6a35fbda447742b52bd60a022ea10a4df4206bb..dc38643775384624d7c4bdea8567832837b1be7e 100644 (file)
--- a/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_ethtool.c
@@ -345,27 +345,29 @@ static int mana_set_channels(struct net_device *ndev,
        struct mana_port_context *apc = netdev_priv(ndev);
        unsigned int new_count = channels->combined_count;
        unsigned int old_count = apc->num_queues;
-       int err, err2;
+       int err;
+
+       err = mana_pre_alloc_rxbufs(apc, ndev->mtu, new_count);
+       if (err) {
+               netdev_err(ndev, "Insufficient memory for new allocations");
+               return err;
+       }
 
        err = mana_detach(ndev, false);
        if (err) {
                netdev_err(ndev, "mana_detach failed: %d\n", err);
-               return err;
+               goto out;
        }
 
        apc->num_queues = new_count;
        err = mana_attach(ndev);
-       if (!err)
-               return 0;
-
-       netdev_err(ndev, "mana_attach failed: %d\n", err);
-
-       /* Try to roll it back to the old configuration. */
-       apc->num_queues = old_count;
-       err2 = mana_attach(ndev);
-       if (err2)
-               netdev_err(ndev, "mana re-attach failed: %d\n", err2);
+       if (err) {
+               apc->num_queues = old_count;
+               netdev_err(ndev, "mana_attach failed: %d\n", err);
+       }
 
+out:
+       mana_pre_dealloc_rxbufs(apc);
        return err;
 }
 
@@ -414,7 +416,7 @@ static int mana_set_ringparam(struct net_device *ndev,
 
        /* pre-allocating new buffers to prevent failures in mana_attach() later */
        apc->rx_queue_size = new_rx;
-       err = mana_pre_alloc_rxbufs(apc, ndev->mtu);
+       err = mana_pre_alloc_rxbufs(apc, ndev->mtu, apc->num_queues);
        apc->rx_queue_size = old_rx;
        if (err) {
                netdev_err(ndev, "Insufficient memory for new allocations\n");

diff --git a/include/net/mana/mana.h b/include/net/mana/mana.h
index 1f869624811d059975c095de00aade87dd325050..dfbf78d4e557e447320c6bb0bdc5bd7ac4fac496 100644 (file)
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -488,7 +488,7 @@ struct bpf_prog *mana_xdp_get(struct mana_port_context *apc);
 void mana_chn_setxdp(struct mana_port_context *apc, struct bpf_prog *prog);
 int mana_bpf(struct net_device *ndev, struct netdev_bpf *bpf);
 void mana_query_gf_stats(struct mana_port_context *apc);
-int mana_pre_alloc_rxbufs(struct mana_port_context *apc, int mtu);
+int mana_pre_alloc_rxbufs(struct mana_port_context *apc, int mtu, int num_queues);
 void mana_pre_dealloc_rxbufs(struct mana_port_context *apc);
 
 extern const struct ethtool_ops mana_ethtool_ops;