This is a note to let you know that I've just added the patch titled
net: dpaa: avoid on-stack arrays of NR_CPUS elements
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-dpaa-avoid-on-stack-arrays-of-nr_cpus-elements.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0d0481511c5bb2eaeea4fc462a5e431c833e8764
Author: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Date: Sun Jul 14 01:53:32 2024 +0300
net: dpaa: avoid on-stack arrays of NR_CPUS elements
[ Upstream commit 555a05d84ca2c587e2d4777006e2c2fb3dfbd91d ]
The dpaa-eth driver is written for PowerPC and Arm SoCs which have 1-24
CPUs. It depends on CONFIG_NR_CPUS having a reasonably small value in
Kconfig. Otherwise, there are 2 functions which allocate on-stack arrays
of NR_CPUS elements, and these can quickly explode in size, leading to
warnings such as:
drivers/net/ethernet/freescale/dpaa/dpaa_eth.c:3280:12: warning:
stack frame size (16664) exceeds limit (2048) in 'dpaa_eth_probe' [-Wframe-larger-than]
The problem is twofold:
- Reducing the array size to the boot-time num_possible_cpus() (rather
than the compile-time NR_CPUS) creates a variable-length array,
which should be avoided in the Linux kernel.
- Using NR_CPUS as an array size makes the driver blow up in stack
consumption with generic, as opposed to hand-crafted, .config files.
A simple solution is to use dynamic allocation for num_possible_cpus()
elements (aka a small number determined at runtime).
Link: https://lore.kernel.org/all/202406261920.l5pzM1rj-lkp@xxxxxxxxx/
Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
Reviewed-by: Breno Leitao <leitao@xxxxxxxxxx>
Acked-by: Madalin Bucur <madalin.bucur@xxxxxxxxxxx>
Link: https://patch.msgid.link/20240713225336.1746343-2-vladimir.oltean@xxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
index dcbc598b11c6..c6a3eefd83bf 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
@@ -931,14 +931,18 @@ static inline void dpaa_setup_egress(const struct dpaa_priv *priv,
}
}
-static void dpaa_fq_setup(struct dpaa_priv *priv,
- const struct dpaa_fq_cbs *fq_cbs,
- struct fman_port *tx_port)
+static int dpaa_fq_setup(struct dpaa_priv *priv,
+ const struct dpaa_fq_cbs *fq_cbs,
+ struct fman_port *tx_port)
{
int egress_cnt = 0, conf_cnt = 0, num_portals = 0, portal_cnt = 0, cpu;
const cpumask_t *affine_cpus = qman_affine_cpus();
- u16 channels[NR_CPUS];
struct dpaa_fq *fq;
+ u16 *channels;
+
+ channels = kcalloc(num_possible_cpus(), sizeof(u16), GFP_KERNEL);
+ if (!channels)
+ return -ENOMEM;
for_each_cpu_and(cpu, affine_cpus, cpu_online_mask)
channels[num_portals++] = qman_affine_channel(cpu);
@@ -997,6 +1001,10 @@ static void dpaa_fq_setup(struct dpaa_priv *priv,
break;
}
}
+
+ kfree(channels);
+
+ return 0;
}
static inline int dpaa_tx_fq_to_id(const struct dpaa_priv *priv,
@@ -3416,7 +3424,9 @@ static int dpaa_eth_probe(struct platform_device *pdev)
*/
dpaa_eth_add_channel(priv->channel, &pdev->dev);
- dpaa_fq_setup(priv, &dpaa_fq_cbs, priv->mac_dev->port[TX]);
+ err = dpaa_fq_setup(priv, &dpaa_fq_cbs, priv->mac_dev->port[TX]);
+ if (err)
+ goto free_dpaa_bps;
/* Create a congestion group for this netdev, with
* dynamically-allocated CGR ID.
diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c b/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c
index 5bd0b36d1feb..3f8cd4a7d845 100644
--- a/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c
+++ b/drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c
@@ -457,12 +457,16 @@ static int dpaa_set_coalesce(struct net_device *dev,
struct netlink_ext_ack *extack)
{
const cpumask_t *cpus = qman_affine_cpus();
- bool needs_revert[NR_CPUS] = {false};
struct qman_portal *portal;
u32 period, prev_period;
u8 thresh, prev_thresh;
+ bool *needs_revert;
int cpu, res;
+ needs_revert = kcalloc(num_possible_cpus(), sizeof(bool), GFP_KERNEL);
+ if (!needs_revert)
+ return -ENOMEM;
+
period = c->rx_coalesce_usecs;
thresh = c->rx_max_coalesced_frames;
@@ -485,6 +489,8 @@ static int dpaa_set_coalesce(struct net_device *dev,
needs_revert[cpu] = true;
}
+ kfree(needs_revert);
+
return 0;
revert_values:
@@ -498,6 +504,8 @@ static int dpaa_set_coalesce(struct net_device *dev,
qman_dqrr_set_ithresh(portal, prev_thresh);
}
+ kfree(needs_revert);
+
return res;
}
