diff mbox series

[SRU,o:azure,2/2] net: mana: Improve mana_set_channels() in low mem conditions

Message ID 20241107230842.83344-5-vinicius.peixoto@canonical.com
State New
Headers show
Series None | expand

Commit Message

Vinicius Peixoto Nov. 7, 2024, 11:08 p.m. UTC 
From: Shradha Gupta <shradhagupta@linux.microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/2086863

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>
(cherry picked from commit 1705341485ff1eec097dfa26891d03afe5907e16)
Signed-off-by: Vinicius Peixoto <vinicius.peixoto@canonical.com>
---
 drivers/net/ethernet/microsoft/mana/mana_en.c |  6 ++--
 .../ethernet/microsoft/mana/mana_ethtool.c    | 28 ++++++++++---------
 include/net/mana/mana.h                       |  2 +-
 3 files changed, 19 insertions(+), 17 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index eeabc8ef3cfb..c47266d1c7c2 100644
--- 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 d6a35fbda447..dc3864377538 100644
--- 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 59770dbc9f08..f2a5200d8a0f 100644
--- a/include/net/mana/mana.h
+++ b/include/net/mana/mana.h
@@ -490,7 +490,7 @@  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;