On Sun, 14 Jun 2009 04:15:28 pm Herbert Xu wrote:

On Sat, Jun 13, 2009 at 10:00:37PM +0930, Rusty Russell wrote:

quoted

But re your comment that the 67 drivers using TX_BUSY are doing it
because of driver bugs, that's hard to believe.  It either hardly ever
happens (in which case just drop the packet), or it happens (in which
case we should handle it correctly).

Most of them just do this:

start_xmit:

if (unlikely(queue is full)) {
	/* This should never happen. */
	return TX_BUSY;
}

OK, so I did a rough audit, trying to figure out the "never happens" ones (N, 
could be kfree_skb(skb); return NETDEV_TX_OK) from the "will actually happen" 
ones (Y).

One question: can netif_queue_stopped() ever be true inside start_xmit?  Some 
drivers test that, like sun3lance.c.

Some have multiple returns, and some are unclear, but my best guess on a 
quickish reading is below.

Summary: we still have about 54 in-tree drivers which actually use 
NETDEV_TX_BUSY for normal paths.  Can I fix it now?

Thanks,
Rusty.

sungem.c: Y, N
fs_enet: N
mace.c: N
sh_eth.c: Y
de620.c: N
acenic.c: N (but goes through stupid hoops to avoid it)
e1000_main.c: N, Y
korina.c: N (Buggy: frees skb and returns TX_BUSY.)
sky2.c: N
cassini.c: N
ixgbe: N
b44.c: N, Y, Y (last two buggy: OOM, does not stop q)
macb.c: N
niu.c: N
smctr.c: N
olympic.c: Y
tms380tr.c: N
3c359.c: Y
lanstreamer.c: Y
lib8390.c: N
xirc2ps_cs.c: Y
smc91c92_cs.c: N
fmvj18x_cs.c: N (and buggy: can't happen AFAICT, and return 0 above?)
axnet_cs.c: N
smsc9420.c: N (and buggy: doesn't stop q)
mkiss.c: N (In xmit, can netif_running be false? Can netif_queue_stopped?)
skge.c: N
qlge: N, N, Y, N (buggy, OOM, does not stop q) 
chelsio: N
s2io.c: Y, Y?
macmace.c: N
3c505.c: Y
defxx.c: Y
myri10ge: N
sbni.c: Y
wanxl.c: N
cycx_x25.c: N, N, Y?
dlci.c: Y
qla3xxx.c: N, N (buggy, OOM, does not stop q), Y, N, 
tlan.c: Y
skfp.c: N
cs89x0.c: N
smc9194.c: N
fec_mpc52xx.c: N
mv643xx_eth.c: N (buggy, OOM, does not stop q)
ll_temac_main.c: Y, Y
netxen: Y
tsi108_eth.c: N, N
ni65.c: N
sunhme.c: N
atl1c.c: Y
ps3_gelic_net.c: Y
igbvf: N
csgb3.c: N
ks8695net.c: N, N (buggy, neither stops q, latter OOM)
ether3.c: N
at91_ether.c: N
bnx2x_main.c: N, N
dm9000.c: N
jme.c: N
3c537.c: Y (plus, leak on skb_padto fail)
arcnet.c: N?
3c59x.c: N
au1000_eth.c: Y
ixgb: N
de600.c: N, N, N
myri_sbus.c: Y
bnx2.c: N
atl1e: Y
sonic.c: who cares, that won't even compile... (missing semicolon)
sun3_82586.c: N
3c515.c: N
ibm_newemac.c: Y
donaubae.c:Y?, Y?, Y?, Y (but never stops q)
sir_dev.c: Y
au1k_ir.c: Y, Y
cpmac.c: N (no stop q, and leak on skb_padto fail), Y
davinci_emac.c: N (no stop q), Y
de2104x.c: N
uli526x.c: N
dmfe.c: N
xircom_cb.c: N
iwmc3200wifi: Y
orinoco: N, N, N, N (no stop q)
atmel.c: Y
p54common.c: N, Y?
arlan-main.c: Y?
libipw_tx.c: Y (no stop q), N (alloc failure)
hostap_80211_tx.c: Y
strip.c: N
wavelan.c: N, N, N
at76c50x-usb.c: N
libertas/tx.c: Y
ray_cs.c: N, N
airo.c: Y, Y, Y
plip.c: N, N, N (starts q, BUSY on too big pkt?)
ns83820.c: N, N
ehea: Y, Y (no stop q)
rionet.c: N
enic: N
sis900.c: N
starfire.c: Y
r6040.c: N
sun3lance.c: N, N
sfc: Y, N, Y
mac89x0.c: N
sb1250-mac.c: Y
pasemi_mac.c: Y
8139cp.c: N
e1000e: N
r8169.c: N?
sis190.c: N
e100.c: N
tg3.c: N, Y?, N
fec.c: N (no stop q), N
hamachi.c: N
forcedeth.c: Y, Y
vxge: Y?, Y?
ks8842.c: Y
spider_net.c: Y
igb: N
ewrk3.c: N
gianfar.c: Y
sunvnet.c: N
mlx4: Y
atlx: Y, Y