xiaomi-sm8450/android_kernel_xiaomi_sm8450
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filter: optimize sk_run_filter

Ver código fonte 
Remove pc variable to avoid arithmetic to compute fentry at each filter
instruction. Jumps directly manipulate fentry pointer.

As the last instruction of filter[] is guaranteed to be a RETURN, and
all jumps are before the last instruction, we dont need to check filter
bounds (number of instructions in filter array) at each iteration, so we
remove it from sk_run_filter() params.

On x86_32 remove f_k var introduced in commit 57fe93b374
(filter: make sure filters dont read uninitialized memory)

Note : We could use a CONFIG_ARCH_HAS_{FEW|MANY}_REGISTERS in order to
avoid too many ifdefs in this code.

This helps compiler to use cpu registers to hold fentry and A
accumulator.

On x86_32, this saves 401 bytes, and more important, sk_run_filter()
runs much faster because less register pressure (One less conditional
branch per BPF instruction)

# size net/core/filter.o net/core/filter_pre.o
   text    data     bss     dec     hex filename
   2948       0       0    2948     b84 net/core/filter.o
   3349       0       0    3349     d15 net/core/filter_pre.o

on x86_64 :
# size net/core/filter.o net/core/filter_pre.o
   text    data     bss     dec     hex filename
   5173       0       0    5173    1435 net/core/filter.o
   5224       0       0    5224    1468 net/core/filter_pre.o

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Esse commit está contido em:
Eric Dumazet
2010-11-19 09:49:59 -08:00
commit de David S. Miller
pai 0a80410dc5
commit 93aaae2e01
6 arquivos alterados com 61 adições e 64 exclusões
Baixar arquivo de patch Baixar arquivo de diferenças Expandir todos os arquivos Colapsar todos os arquivos

14
drivers/isdn/i4l/isdn_ppp.c
Ver arquivo

@@ -1147,15 +1147,14 @@ isdn_ppp_push_higher(isdn_net_dev * net_dev, isdn_net_local * lp, struct sk_buff
}
if (is->pass_filter
&& sk_run_filter(skb, is->pass_filter, is->pass_len) == 0) {
&& sk_run_filter(skb, is->pass_filter) == 0) {
if (is->debug & 0x2)
printk(KERN_DEBUG "IPPP: inbound frame filtered.\n");
kfree_skb(skb);
return;
}
if (!(is->active_filter
&& sk_run_filter(skb, is->active_filter,
is->active_len) == 0)) {
&& sk_run_filter(skb, is->active_filter) == 0)) {
if (is->debug & 0x2)
printk(KERN_DEBUG "IPPP: link-active filter: reseting huptimer.\n");
lp->huptimer = 0;
@@ -1294,15 +1293,14 @@ isdn_ppp_xmit(struct sk_buff *skb, struct net_device *netdev)
}
if (ipt->pass_filter
&& sk_run_filter(skb, ipt->pass_filter, ipt->pass_len) == 0) {
&& sk_run_filter(skb, ipt->pass_filter) == 0) {
if (ipt->debug & 0x4)
printk(KERN_DEBUG "IPPP: outbound frame filtered.\n");
kfree_skb(skb);
goto unlock;
}
if (!(ipt->active_filter
&& sk_run_filter(skb, ipt->active_filter,
ipt->active_len) == 0)) {
&& sk_run_filter(skb, ipt->active_filter) == 0)) {
if (ipt->debug & 0x4)
printk(KERN_DEBUG "IPPP: link-active filter: reseting huptimer.\n");
lp->huptimer = 0;
@@ -1492,9 +1490,9 @@ int isdn_ppp_autodial_filter(struct sk_buff *skb, isdn_net_local *lp)
}
drop |= is->pass_filter
&& sk_run_filter(skb, is->pass_filter, is->pass_len) == 0;
&& sk_run_filter(skb, is->pass_filter) == 0;
drop |= is->active_filter
&& sk_run_filter(skb, is->active_filter, is->active_len) == 0;
&& sk_run_filter(skb, is->active_filter) == 0;
skb_push(skb, IPPP_MAX_HEADER - 4);
return drop;