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net: dpaa: avoid on-stack arrays of NR_CPUS elements

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[ Upstream commit 555a05d84c ]

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@intel.com/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Acked-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Link: https://patch.msgid.link/20240713225336.1746343-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Vladimir Oltean 2024-07-14 01:53:32 +03:00 committed by Greg Kroah-Hartman
parent 04e85a3285
commit 289d0822be
2 changed files with 24 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
View File

@ -910,14 +910,18 @@ 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);
@ -976,6 +980,10 @@ 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,
@ -3444,7 +3452,9 @@ 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.

10
drivers/net/ethernet/freescale/dpaa/dpaa_ethtool.c
View File

@ -541,12 +541,16 @@ 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;
@ -569,6 +573,8 @@ static int dpaa_set_coalesce(struct net_device *dev,
needs_revert[cpu] = true;
}
kfree(needs_revert);
return 0;
revert_values:
@ -582,6 +588,8 @@ revert_values:
qman_dqrr_set_ithresh(portal, prev_thresh);
}
kfree(needs_revert);
return res;
}