Re: [PATCH net-next] tls: Skip zerocopy path for ITER_KVEC

[David Miller]

From: David Miller 
Date: Tue, 24 Jul 2018 14:38:02 -0700 (PDT)

> From: Doron Roberts-Kedes 
> Date: Fri, 20 Jul 2018 11:19:00 -0700
> 
>> The zerocopy path ultimately calls iov_iter_get_pages, which defines the
>> step function for ITER_KVECs as simply, return -EFAULT. Taking the
>> non-zerocopy path for ITER_KVECs avoids the unnecessary fallback. 
>> 
>> See 
>> https://lore.kernel.org/lkml/20150401023311.gl29...@zeniv.linux.org.uk/T/#u
>> for a discussion of why zerocopy for vmalloc data is not a good idea. 
>> 
>> Discovered while testing NBD traffic encrypted with ktls.
>> 
>> Fixes: c46234ebb4d1 ("tls: RX path for ktls")
>> Signed-off-by: Doron Roberts-Kedes 
> 
> Applied to net-next, thanks.

Actually, I reverted.  Please fix this warning:

net/tls/tls_sw.c: In function ‘tls_sw_sendmsg’:
net/tls/tls_sw.c:414:3: warning: ISO C90 forbids mixed declarations and code 
[-Wdeclaration-after-statement]
   bool iskvec = msg->msg_iter.type & ITER_KVEC;
   ^~~~
net/tls/tls_sw.c: In function ‘tls_sw_recvmsg’:
net/tls/tls_sw.c:823:4: warning: ISO C90 forbids mixed declarations and code 
[-Wdeclaration-after-statement]
bool iskvec = msg->msg_iter.type & ITER_KVEC;
^~~~

Re: [PATCH net-next] tls: Skip zerocopy path for ITER_KVEC

[David Miller]

From: Doron Roberts-Kedes 
Date: Fri, 20 Jul 2018 11:19:00 -0700

> The zerocopy path ultimately calls iov_iter_get_pages, which defines the
> step function for ITER_KVECs as simply, return -EFAULT. Taking the
> non-zerocopy path for ITER_KVECs avoids the unnecessary fallback. 
> 
> See 
> https://lore.kernel.org/lkml/20150401023311.gl29...@zeniv.linux.org.uk/T/#u
> for a discussion of why zerocopy for vmalloc data is not a good idea. 
> 
> Discovered while testing NBD traffic encrypted with ktls.
> 
> Fixes: c46234ebb4d1 ("tls: RX path for ktls")
> Signed-off-by: Doron Roberts-Kedes 

Applied to net-next, thanks.

[PATCH net-next] tls: Skip zerocopy path for ITER_KVEC

[Doron Roberts-Kedes]

The zerocopy path ultimately calls iov_iter_get_pages, which defines the
step function for ITER_KVECs as simply, return -EFAULT. Taking the
non-zerocopy path for ITER_KVECs avoids the unnecessary fallback. 

See https://lore.kernel.org/lkml/20150401023311.gl29...@zeniv.linux.org.uk/T/#u
for a discussion of why zerocopy for vmalloc data is not a good idea. 

Discovered while testing NBD traffic encrypted with ktls.

Fixes: c46234ebb4d1 ("tls: RX path for ktls")
Signed-off-by: Doron Roberts-Kedes 
---
 net/tls/tls_sw.c | 6 --
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 4618f1c31137..ef15e35232dd 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -426,7 +426,8 @@ int tls_sw_sendmsg(struct sock *sk, struct msghdr *msg, 
size_t size)
full_record = true;
}
 
-   if (full_record || eor) {
+   bool iskvec = msg->msg_iter.type & ITER_KVEC;
+   if (!iskvec && (full_record || eor)) {
ret = zerocopy_from_iter(sk, &msg->msg_iter,
try_to_copy, &ctx->sg_plaintext_num_elem,
&ctx->sg_plaintext_size,
@@ -804,7 +805,8 @@ int tls_sw_recvmsg(struct sock *sk,
page_count = iov_iter_npages(&msg->msg_iter,
 MAX_SKB_FRAGS);
to_copy = rxm->full_len - tls_ctx->rx.overhead_size;
-   if (to_copy <= len && page_count < MAX_SKB_FRAGS &&
+   bool iskvec = msg->msg_iter.type & ITER_KVEC;
+   if (!iskvec && to_copy <= len && page_count < 
MAX_SKB_FRAGS &&
likely(!(flags & MSG_PEEK)))  {
struct scatterlist sgin[MAX_SKB_FRAGS + 1];
int pages = 0;
-- 
2.17.1