* [PATCH 15/16] netfilter: Replace smp_read_barrier_depends() with lockless_dereference()
[not found] <1415906662-4576-1-git-send-email-bobby.prani@gmail.com>
@ 2014-11-13 19:24 ` Pranith Kumar
2014-11-13 19:24 ` [PATCH 16/16] rxrpc: " Pranith Kumar
2014-11-13 20:07 ` [RFC PATCH 00/16] Replace smp_read_barrier_depends() with lockless_derefrence() Paul E. McKenney
2 siblings, 0 replies; 8+ messages in thread
From: Pranith Kumar @ 2014-11-13 19:24 UTC (permalink / raw)
To: Pablo Neira Ayuso, Patrick McHardy, Jozsef Kadlecsik,
David S. Miller, Alexey Kuznetsov, James Morris,
Hideaki YOSHIFUJI, netfilter-devel, coreteam,
open list:NETWORKING [IPv4/..., open list
Cc: paulmck
Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
net/ipv4/netfilter/arp_tables.c | 3 +--
net/ipv4/netfilter/ip_tables.c | 3 +--
net/ipv6/netfilter/ip6_tables.c | 3 +--
3 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index f95b6f9..fc7533d 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -270,12 +270,11 @@ unsigned int arpt_do_table(struct sk_buff *skb,
local_bh_disable();
addend = xt_write_recseq_begin();
- private = table->private;
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
- smp_read_barrier_depends();
+ private = lockless_dereference(table->private);
table_base = private->entries[smp_processor_id()];
e = get_entry(table_base, private->hook_entry[hook]);
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 99e810f..e0fd044 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -325,13 +325,12 @@ ipt_do_table(struct sk_buff *skb,
IP_NF_ASSERT(table->valid_hooks & (1 << hook));
local_bh_disable();
addend = xt_write_recseq_begin();
- private = table->private;
cpu = smp_processor_id();
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
- smp_read_barrier_depends();
+ private = lockless_dereference(table->private);
table_base = private->entries[cpu];
jumpstack = (struct ipt_entry **)private->jumpstack[cpu];
stackptr = per_cpu_ptr(private->stackptr, cpu);
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index e080fbb..0459d6a 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -348,12 +348,11 @@ ip6t_do_table(struct sk_buff *skb,
local_bh_disable();
addend = xt_write_recseq_begin();
- private = table->private;
/*
* Ensure we load private-> members after we've fetched the base
* pointer.
*/
- smp_read_barrier_depends();
+ private = lockless_dereference(table->private);
cpu = smp_processor_id();
table_base = private->entries[cpu];
jumpstack = (struct ip6t_entry **)private->jumpstack[cpu];
--
1.9.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()
[not found] <1415906662-4576-1-git-send-email-bobby.prani@gmail.com>
2014-11-13 19:24 ` [PATCH 15/16] netfilter: Replace smp_read_barrier_depends() with lockless_dereference() Pranith Kumar
@ 2014-11-13 19:24 ` Pranith Kumar
2014-11-13 20:17 ` David Howells
2014-11-13 20:47 ` David Howells
2014-11-13 20:07 ` [RFC PATCH 00/16] Replace smp_read_barrier_depends() with lockless_derefrence() Paul E. McKenney
2 siblings, 2 replies; 8+ messages in thread
From: Pranith Kumar @ 2014-11-13 19:24 UTC (permalink / raw)
To: David S. Miller, David Howells, Dan Carpenter,
open list:NETWORKING [GENERAL], open list
Cc: paulmck
Recently lockless_dereference() was added which can be used in place of
hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
net/rxrpc/ar-ack.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/net/rxrpc/ar-ack.c b/net/rxrpc/ar-ack.c
index c6be17a..9237448 100644
--- a/net/rxrpc/ar-ack.c
+++ b/net/rxrpc/ar-ack.c
@@ -234,8 +234,7 @@ static void rxrpc_resend(struct rxrpc_call *call)
loop != call->acks_head || stop;
loop = (loop + 1) & (call->acks_winsz - 1)
) {
- p_txb = call->acks_window + loop;
- smp_read_barrier_depends();
+ p_txb = lockless_dereference(call)->acks_window + loop;
if (*p_txb & 1)
continue;
@@ -303,8 +302,7 @@ static void rxrpc_resend_timer(struct rxrpc_call *call)
loop != call->acks_head;
loop = (loop + 1) & (call->acks_winsz - 1)
) {
- p_txb = call->acks_window + loop;
- smp_read_barrier_depends();
+ p_txb = lockless_dereference(call)->acks_window + loop;
txb = (struct sk_buff *) (*p_txb & ~1);
sp = rxrpc_skb(txb);
@@ -354,9 +352,10 @@ static int rxrpc_process_soft_ACKs(struct rxrpc_call *call,
resend = 0;
resend_at = 0;
for (loop = 0; loop < ack->nAcks; loop++) {
- p_txb = call->acks_window;
- p_txb += (call->acks_tail + loop) & (call->acks_winsz - 1);
- smp_read_barrier_depends();
+ struct rxrpc_call *callp = lockless_dereference(call);
+
+ p_txb = callp->acks_window;
+ p_txb += (callp->acks_tail + loop) & (callp->acks_winsz - 1);
txb = (struct sk_buff *) (*p_txb & ~1);
sp = rxrpc_skb(txb);
@@ -385,8 +384,7 @@ static int rxrpc_process_soft_ACKs(struct rxrpc_call *call,
loop != call->acks_head;
loop = (loop + 1) & (call->acks_winsz - 1)
) {
- p_txb = call->acks_window + loop;
- smp_read_barrier_depends();
+ p_txb = lockless_dereference(call)->acks_window + loop;
txb = (struct sk_buff *) (*p_txb & ~1);
sp = rxrpc_skb(txb);
@@ -432,8 +430,7 @@ static void rxrpc_rotate_tx_window(struct rxrpc_call *call, u32 hard)
ASSERTCMP(hard - call->acks_hard, <=, win);
while (call->acks_hard < hard) {
- smp_read_barrier_depends();
- _skb = call->acks_window[tail] & ~1;
+ _skb = lockless_dereference(call)->acks_window[tail] & ~1;
rxrpc_free_skb((struct sk_buff *) _skb);
old_tail = tail;
tail = (tail + 1) & (call->acks_winsz - 1);
@@ -577,8 +574,7 @@ static void rxrpc_zap_tx_window(struct rxrpc_call *call)
call->acks_window = NULL;
while (CIRC_CNT(call->acks_head, call->acks_tail, winsz) > 0) {
- tail = call->acks_tail;
- smp_read_barrier_depends();
+ tail = lockless_dereference(call)->acks_tail;
_skb = acks_window[tail] & ~1;
smp_mb();
call->acks_tail = (call->acks_tail + 1) & (winsz - 1);
--
1.9.1
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()
2014-11-13 19:24 ` [PATCH 16/16] rxrpc: " Pranith Kumar
@ 2014-11-13 20:17 ` David Howells
2014-11-13 20:47 ` David Howells
1 sibling, 0 replies; 8+ messages in thread
From: David Howells @ 2014-11-13 20:17 UTC (permalink / raw)
To: Pranith Kumar
Cc: dhowells, David S. Miller, Dan Carpenter,
open list:NETWORKING [GENERAL], open list, paulmck
Pranith Kumar <bobby.prani@gmail.com> wrote:
> loop != call->acks_head || stop;
> loop = (loop + 1) & (call->acks_winsz - 1)
> ) {
> - p_txb = call->acks_window + loop;
> - smp_read_barrier_depends();
> + p_txb = lockless_dereference(call)->acks_window + loop;
Nack. You've stuck an implicit barrier on a dereference that doesn't matter.
And similar for other hunks of this patch.
David
^ permalink raw reply [flat|nested] 8+ messages in thread* Re: [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()
2014-11-13 19:24 ` [PATCH 16/16] rxrpc: " Pranith Kumar
2014-11-13 20:17 ` David Howells
@ 2014-11-13 20:47 ` David Howells
2014-11-13 21:55 ` Pranith Kumar
1 sibling, 1 reply; 8+ messages in thread
From: David Howells @ 2014-11-13 20:47 UTC (permalink / raw)
To: Pranith Kumar
Cc: dhowells, David S. Miller, Dan Carpenter,
open list:NETWORKING [GENERAL], open list, paulmck
Pranith Kumar <bobby.prani@gmail.com> wrote:
> Recently lockless_dereference() was added which can be used in place of
> hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
Actually, the use of smp_read_barrier_depends() is wrong in circular
buffering. See Documentation/circular-buffers.txt
David
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 16/16] rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()
2014-11-13 20:47 ` David Howells
@ 2014-11-13 21:55 ` Pranith Kumar
2014-11-13 23:07 ` David Howells
0 siblings, 1 reply; 8+ messages in thread
From: Pranith Kumar @ 2014-11-13 21:55 UTC (permalink / raw)
To: David Howells
Cc: David S. Miller, Dan Carpenter, open list:NETWORKING [GENERAL],
open list, paulmck
On 11/13/2014 03:47 PM, David Howells wrote:
> Pranith Kumar <bobby.prani@gmail.com> wrote:
>
>> Recently lockless_dereference() was added which can be used in place of
>> hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
>
> Actually, the use of smp_read_barrier_depends() is wrong in circular
> buffering. See Documentation/circular-buffers.txt
>
OK. Should I send in a patch removing these barriers then?
--
Pranith
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [RFC PATCH 00/16] Replace smp_read_barrier_depends() with lockless_derefrence()
[not found] <1415906662-4576-1-git-send-email-bobby.prani@gmail.com>
2014-11-13 19:24 ` [PATCH 15/16] netfilter: Replace smp_read_barrier_depends() with lockless_dereference() Pranith Kumar
2014-11-13 19:24 ` [PATCH 16/16] rxrpc: " Pranith Kumar
@ 2014-11-13 20:07 ` Paul E. McKenney
2 siblings, 0 replies; 8+ messages in thread
From: Paul E. McKenney @ 2014-11-13 20:07 UTC (permalink / raw)
To: Pranith Kumar
Cc: Herbert Xu, David S. Miller, Cristian Stoica, Horia Geanta,
Ruchika Gupta, Michael Neuling, Wolfram Sang,
open list:CRYPTO API, open list, Vinod Koul, Dan Williams,
Bartlomiej Zolnierkiewicz, Kyungmin Park, Manuel Schölling,
Dave Jiang, Rashika, open list:DMA GENERIC OFFLO...
On Thu, Nov 13, 2014 at 02:24:06PM -0500, Pranith Kumar wrote:
> Recently lockless_dereference() was added which can be used in place of
> hard-coding smp_read_barrier_depends().
>
> http://lkml.iu.edu/hypermail/linux/kernel/1410.3/04561.html
>
> The following series tries to do this.
>
> There are still some hard-coded locations which I was not sure how to replace
> with. I will send in separate patches/questions regarding them.
Thank you for taking this on! Some questions and comments in response
to the individual patches.
Thanx, Paul
> Pranith Kumar (16):
> crypto: caam - Remove unnecessary smp_read_barrier_depends()
> doc: memory-barriers.txt: Document use of lockless_dereference()
> drivers: dma: Replace smp_read_barrier_depends() with
> lockless_dereference()
> dcache: Replace smp_read_barrier_depends() with lockless_dereference()
> overlayfs: Replace smp_read_barrier_depends() with
> lockless_dereference()
> assoc_array: Replace smp_read_barrier_depends() with
> lockless_dereference()
> hyperv: Replace smp_read_barrier_depends() with lockless_dereference()
> rcupdate: Replace smp_read_barrier_depends() with
> lockless_dereference()
> percpu: Replace smp_read_barrier_depends() with lockless_dereference()
> perf: Replace smp_read_barrier_depends() with lockless_dereference()
> seccomp: Replace smp_read_barrier_depends() with
> lockless_dereference()
> task_work: Replace smp_read_barrier_depends() with
> lockless_dereference()
> ksm: Replace smp_read_barrier_depends() with lockless_dereference()
> slab: Replace smp_read_barrier_depends() with lockless_dereference()
> netfilter: Replace smp_read_barrier_depends() with
> lockless_dereference()
> rxrpc: Replace smp_read_barrier_depends() with lockless_dereference()
>
> Documentation/memory-barriers.txt | 2 +-
> drivers/crypto/caam/jr.c | 3 ---
> drivers/dma/ioat/dma_v2.c | 3 +--
> drivers/dma/ioat/dma_v3.c | 3 +--
> fs/dcache.c | 7 ++-----
> fs/overlayfs/super.c | 4 +---
> include/linux/assoc_array_priv.h | 11 +++++++----
> include/linux/hyperv.h | 9 ++++-----
> include/linux/percpu-refcount.h | 4 +---
> include/linux/rcupdate.h | 10 +++++-----
> kernel/events/core.c | 3 +--
> kernel/events/uprobes.c | 8 ++++----
> kernel/seccomp.c | 7 +++----
> kernel/task_work.c | 3 +--
> lib/assoc_array.c | 7 -------
> mm/ksm.c | 7 +++----
> mm/slab.h | 6 +++---
> net/ipv4/netfilter/arp_tables.c | 3 +--
> net/ipv4/netfilter/ip_tables.c | 3 +--
> net/ipv6/netfilter/ip6_tables.c | 3 +--
> net/rxrpc/ar-ack.c | 22 +++++++++-------------
> security/keys/keyring.c | 6 ------
> 22 files changed, 50 insertions(+), 84 deletions(-)
>
> --
> 1.9.1
>
--
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^ permalink raw reply [flat|nested] 8+ messages in thread