lkml.org 
[lkml]   [2018]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2] net: dsa: Remove VLA usage
From: Salvatore Mesoraca <s.mesoraca16@gmail.com>

We avoid 2 VLAs by using a pre-allocated field in dsa_switch. We also
try to avoid dynamic allocation whenever possible (when using fewer than
bits-per-long ports, which is the common case).

Link: http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Link: http://lkml.kernel.org/r/20180505185145.GB32630@lunn.ch
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
[kees: tweak commit subject and message slightly]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
include/net/dsa.h | 3 +++
net/dsa/dsa2.c | 14 ++++++++++++++
net/dsa/switch.c | 22 ++++++++++------------
3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index fdbd6082945d..461e8a7661b7 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -259,6 +259,9 @@ struct dsa_switch {
/* Number of switch port queues */
unsigned int num_tx_queues;

+ unsigned long *bitmap;
+ unsigned long _bitmap;
+
/* Dynamically allocated ports, keep last */
size_t num_ports;
struct dsa_port ports[];
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index dc5d9af3dc80..a1917025e155 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -775,6 +775,20 @@ struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n)
if (!ds)
return NULL;

+ /* We avoid allocating memory outside dsa_switch
+ * if it is not needed.
+ */
+ if (n <= sizeof(ds->_bitmap) * 8) {
+ ds->bitmap = &ds->_bitmap;
+ } else {
+ ds->bitmap = devm_kcalloc(dev,
+ BITS_TO_LONGS(n),
+ sizeof(unsigned long),
+ GFP_KERNEL);
+ if (unlikely(!ds->bitmap))
+ return NULL;
+ }
+
ds->dev = dev;
ds->num_ports = n;

diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index b93511726069..142b294d3446 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c
@@ -136,21 +136,20 @@ static int dsa_switch_mdb_add(struct dsa_switch *ds,
{
const struct switchdev_obj_port_mdb *mdb = info->mdb;
struct switchdev_trans *trans = info->trans;
- DECLARE_BITMAP(group, ds->num_ports);
int port;

/* Build a mask of Multicast group members */
- bitmap_zero(group, ds->num_ports);
+ bitmap_zero(ds->bitmap, ds->num_ports);
if (ds->index == info->sw_index)
- set_bit(info->port, group);
+ set_bit(info->port, ds->bitmap);
for (port = 0; port < ds->num_ports; port++)
if (dsa_is_dsa_port(ds, port))
- set_bit(port, group);
+ set_bit(port, ds->bitmap);

if (switchdev_trans_ph_prepare(trans))
- return dsa_switch_mdb_prepare_bitmap(ds, mdb, group);
+ return dsa_switch_mdb_prepare_bitmap(ds, mdb, ds->bitmap);

- dsa_switch_mdb_add_bitmap(ds, mdb, group);
+ dsa_switch_mdb_add_bitmap(ds, mdb, ds->bitmap);

return 0;
}
@@ -204,21 +203,20 @@ static int dsa_switch_vlan_add(struct dsa_switch *ds,
{
const struct switchdev_obj_port_vlan *vlan = info->vlan;
struct switchdev_trans *trans = info->trans;
- DECLARE_BITMAP(members, ds->num_ports);
int port;

/* Build a mask of VLAN members */
- bitmap_zero(members, ds->num_ports);
+ bitmap_zero(ds->bitmap, ds->num_ports);
if (ds->index == info->sw_index)
- set_bit(info->port, members);
+ set_bit(info->port, ds->bitmap);
for (port = 0; port < ds->num_ports; port++)
if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
- set_bit(port, members);
+ set_bit(port, ds->bitmap);

if (switchdev_trans_ph_prepare(trans))
- return dsa_switch_vlan_prepare_bitmap(ds, vlan, members);
+ return dsa_switch_vlan_prepare_bitmap(ds, vlan, ds->bitmap);

- dsa_switch_vlan_add_bitmap(ds, vlan, members);
+ dsa_switch_vlan_add_bitmap(ds, vlan, ds->bitmap);

return 0;
}
--
2.17.1

--
Kees Cook
Pixel Security

\
 
 \ /
  Last update: 2018-07-17 06:11    [W:0.117 / U:0.248 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site