* [PATCH] tun: make tun_build_skb() thread safe
@ 2017-08-16 14:14 Jason Wang
2017-08-16 14:29 ` Jason Wang
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Jason Wang @ 2017-08-16 14:14 UTC (permalink / raw)
To: davem, netdev, linux-kernel; +Cc: mst, Eric Dumazet, Jason Wang
From: Eric Dumazet <eric.dumazet@gmail.com>
tun_build_skb() is not thread safe since it uses per queue page frag,
this will break things when multiple threads are sending through same
queue. Switch to use per-thread generator (no lock involved).
Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet")
Tested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/net/tun.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 5892284..c38cd84 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -175,7 +175,6 @@ struct tun_file {
struct list_head next;
struct tun_struct *detached;
struct skb_array tx_array;
- struct page_frag alloc_frag;
};
struct tun_flow_entry {
@@ -578,8 +577,6 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
}
if (tun)
skb_array_cleanup(&tfile->tx_array);
- if (tfile->alloc_frag.page)
- put_page(tfile->alloc_frag.page);
sock_put(&tfile->sk);
}
}
@@ -1272,7 +1269,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
struct virtio_net_hdr *hdr,
int len, int *generic_xdp)
{
- struct page_frag *alloc_frag = &tfile->alloc_frag;
+ struct page_frag *alloc_frag = ¤t->task_frag;
struct sk_buff *skb;
struct bpf_prog *xdp_prog;
int buflen = SKB_DATA_ALIGN(len + TUN_RX_PAD) +
@@ -2580,8 +2577,6 @@ static int tun_chr_open(struct inode *inode, struct file * file)
tfile->sk.sk_write_space = tun_sock_write_space;
tfile->sk.sk_sndbuf = INT_MAX;
- tfile->alloc_frag.page = NULL;
-
file->private_data = tfile;
INIT_LIST_HEAD(&tfile->next);
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: make tun_build_skb() thread safe
2017-08-16 14:14 [PATCH] tun: make tun_build_skb() thread safe Jason Wang
@ 2017-08-16 14:29 ` Jason Wang
2017-08-16 16:55 ` Michael S. Tsirkin
2017-08-16 21:27 ` David Miller
2 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2017-08-16 14:29 UTC (permalink / raw)
To: davem, netdev, linux-kernel; +Cc: mst, Eric Dumazet
On 2017年08月16日 22:14, Jason Wang wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
>
> tun_build_skb() is not thread safe since it uses per queue page frag,
> this will break things when multiple threads are sending through same
> queue. Switch to use per-thread generator (no lock involved).
>
> Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet")
> Tested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> drivers/net/tun.c | 7 +------
Forget to mention, this is for net-next.
Thanks
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: make tun_build_skb() thread safe
2017-08-16 14:14 [PATCH] tun: make tun_build_skb() thread safe Jason Wang
2017-08-16 14:29 ` Jason Wang
@ 2017-08-16 16:55 ` Michael S. Tsirkin
2017-08-17 3:37 ` Jason Wang
2017-08-16 21:27 ` David Miller
2 siblings, 1 reply; 5+ messages in thread
From: Michael S. Tsirkin @ 2017-08-16 16:55 UTC (permalink / raw)
To: Jason Wang; +Cc: davem, netdev, linux-kernel, Eric Dumazet
On Wed, Aug 16, 2017 at 10:14:33PM +0800, Jason Wang wrote:
> From: Eric Dumazet <eric.dumazet@gmail.com>
>
> tun_build_skb() is not thread safe since it uses per queue page frag,
> this will break things when multiple threads are sending through same
> queue. Switch to use per-thread generator (no lock involved).
>
> Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet")
> Tested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Jason, given the switch to task_frag, would it be worth it to look at
using higher order allocs along the lines of
5640f7685831e088fe6c2e1f863a6805962f8e81 as well?
> ---
> drivers/net/tun.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 5892284..c38cd84 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -175,7 +175,6 @@ struct tun_file {
> struct list_head next;
> struct tun_struct *detached;
> struct skb_array tx_array;
> - struct page_frag alloc_frag;
> };
>
> struct tun_flow_entry {
> @@ -578,8 +577,6 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
> }
> if (tun)
> skb_array_cleanup(&tfile->tx_array);
> - if (tfile->alloc_frag.page)
> - put_page(tfile->alloc_frag.page);
> sock_put(&tfile->sk);
> }
> }
> @@ -1272,7 +1269,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
> struct virtio_net_hdr *hdr,
> int len, int *generic_xdp)
> {
> - struct page_frag *alloc_frag = &tfile->alloc_frag;
> + struct page_frag *alloc_frag = ¤t->task_frag;
> struct sk_buff *skb;
> struct bpf_prog *xdp_prog;
> int buflen = SKB_DATA_ALIGN(len + TUN_RX_PAD) +
> @@ -2580,8 +2577,6 @@ static int tun_chr_open(struct inode *inode, struct file * file)
> tfile->sk.sk_write_space = tun_sock_write_space;
> tfile->sk.sk_sndbuf = INT_MAX;
>
> - tfile->alloc_frag.page = NULL;
> -
> file->private_data = tfile;
> INIT_LIST_HEAD(&tfile->next);
>
> --
> 2.7.4
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: make tun_build_skb() thread safe
2017-08-16 14:14 [PATCH] tun: make tun_build_skb() thread safe Jason Wang
2017-08-16 14:29 ` Jason Wang
2017-08-16 16:55 ` Michael S. Tsirkin
@ 2017-08-16 21:27 ` David Miller
2 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2017-08-16 21:27 UTC (permalink / raw)
To: jasowang; +Cc: netdev, linux-kernel, mst, eric.dumazet
From: Jason Wang <jasowang@redhat.com>
Date: Wed, 16 Aug 2017 22:14:33 +0800
> From: Eric Dumazet <eric.dumazet@gmail.com>
>
> tun_build_skb() is not thread safe since it uses per queue page frag,
> this will break things when multiple threads are sending through same
> queue. Switch to use per-thread generator (no lock involved).
>
> Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet")
> Tested-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
Applied, thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tun: make tun_build_skb() thread safe
2017-08-16 16:55 ` Michael S. Tsirkin
@ 2017-08-17 3:37 ` Jason Wang
0 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2017-08-17 3:37 UTC (permalink / raw)
To: Michael S. Tsirkin; +Cc: davem, netdev, linux-kernel, Eric Dumazet
On 2017年08月17日 00:55, Michael S. Tsirkin wrote:
> On Wed, Aug 16, 2017 at 10:14:33PM +0800, Jason Wang wrote:
>> From: Eric Dumazet<eric.dumazet@gmail.com>
>>
>> tun_build_skb() is not thread safe since it uses per queue page frag,
>> this will break things when multiple threads are sending through same
>> queue. Switch to use per-thread generator (no lock involved).
>>
>> Fixes: 66ccbc9c87c2 ("tap: use build_skb() for small packet")
>> Tested-by: Jason Wang<jasowang@redhat.com>
>> Signed-off-by: Eric Dumazet<eric.dumazet@gmail.com>
>> Signed-off-by: Jason Wang<jasowang@redhat.com>
> Acked-by: Michael S. Tsirkin<mst@redhat.com>
>
> Jason, given the switch to task_frag, would it be worth it to look at
> using higher order allocs along the lines of
> 5640f7685831e088fe6c2e1f863a6805962f8e81 as well?
>
I think we've already used high order, don't we?
Thanks
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-08-17 3:37 UTC | newest]
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2017-08-16 14:14 [PATCH] tun: make tun_build_skb() thread safe Jason Wang
2017-08-16 14:29 ` Jason Wang
2017-08-16 16:55 ` Michael S. Tsirkin
2017-08-17 3:37 ` Jason Wang
2017-08-16 21:27 ` David Miller
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