Re: [PATCH 3/4] net: mv643xx_eth: use kzalloc

From: Joe Perches
Date: Wed Sep 09 2015 - 19:25:37 EST


On Wed, 2015-09-09 at 11:45 -0700, Joe Perches wrote:
> On Wed, 2015-09-09 at 20:34 +0200, Rasmus Villemoes wrote:
> > mc_spec and mc_other are u32*, we allocate 0x200 = 512 bytes = 128
> > u32s, and pointer arithmetic makes mc_other point to the latter 64. Then
> > the memory is cleared 256 bytes at a time.
> >
> > It's unusual and slightly obfuscated code, but I don't think it's
> > wrong.

Perhaps this would make the code a bit clearer:

Use kcalloc, decimal sizes, decimal indexing,
and a promiscuous exit block using the same
style as the non-promiscuous multicast block.
---
drivers/net/ethernet/marvell/mv643xx_eth.c | 46 ++++++++++++++----------------
1 file changed, 22 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mv643xx_eth.c b/drivers/net/ethernet/marvell/mv643xx_eth.c
index d52639b..9230ed5 100644
--- a/drivers/net/ethernet/marvell/mv643xx_eth.c
+++ b/drivers/net/ethernet/marvell/mv643xx_eth.c
@@ -1845,32 +1845,19 @@ static void mv643xx_eth_program_multicast_filter(struct net_device *dev)
struct netdev_hw_addr *ha;
int i;

- if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) {
- int port_num;
- u32 accept;
+ if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI))
+ goto promiscuous;

-oom:
- port_num = mp->port_num;
- accept = 0x01010101;
- for (i = 0; i < 0x100; i += 4) {
- wrl(mp, SPECIAL_MCAST_TABLE(port_num) + i, accept);
- wrl(mp, OTHER_MCAST_TABLE(port_num) + i, accept);
- }
- return;
- }
-
- mc_spec = kmalloc(0x200, GFP_ATOMIC);
- if (mc_spec == NULL)
- goto oom;
- mc_other = mc_spec + (0x100 >> 2);
-
- memset(mc_spec, 0, 0x100);
- memset(mc_other, 0, 0x100);
+ /* Allocate both mc_spec and mc_other tables */
+ mc_spec = kcalloc(128, sizeof(u32), GFP_ATOMIC);
+ if (!mc_spec)
+ goto promiscuous;
+ mc_other = &mc_spec[64];

netdev_for_each_mc_addr(ha, dev) {
u8 *a = ha->addr;
u32 *table;
- int entry;
+ u8 entry;

if (memcmp(a, "\x01\x00\x5e\x00\x00", 5) == 0) {
table = mc_spec;
@@ -1883,12 +1870,23 @@ oom:
table[entry >> 2] |= 1 << (8 * (entry & 3));
}

- for (i = 0; i < 0x100; i += 4) {
- wrl(mp, SPECIAL_MCAST_TABLE(mp->port_num) + i, mc_spec[i >> 2]);
- wrl(mp, OTHER_MCAST_TABLE(mp->port_num) + i, mc_other[i >> 2]);
+ for (i = 0; i < 64; i++) {
+ wrl(mp, SPECIAL_MCAST_TABLE(mp->port_num) + i * sizeof(u32),
+ mc_spec[i]);
+ wrl(mp, OTHER_MCAST_TABLE(mp->port_num) + i * sizeof(u32),
+ mc_other[i]);
}

kfree(mc_spec);
+ return;
+
+promiscuous:
+ for (i = 0; i < 64; i++) {
+ wrl(mp, SPECIAL_MCAST_TABLE(mp->port_num) + i * sizeof(u32),
+ 0x01010101u);
+ wrl(mp, OTHER_MCAST_TABLE(mp->port_num) + i * sizeof(u32),
+ 0x01010101u);
+ }
}

static void mv643xx_eth_set_rx_mode(struct net_device *dev)


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