Commit 936ced41 authored Dec 02, 2020 by Arjun Roy Committed by Jakub Kicinski Dec 04, 2020

net-zerocopy: Fast return if inq < PAGE_SIZE



Sometimes, we may call tcp receive zerocopy when inq is 0,
or inq < PAGE_SIZE, in which case we cannot remap pages. In this case,
simply return the appropriate hint for regular copying without taking
mmap_sem.

Signed-off-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 98917cf0

net/ipv4/tcp.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1904,6 +1904,14 @@ static int tcp_zerocopy_receive(struct sock *sk,

		sock_rps_record_flow(sk);

		if (inq < PAGE_SIZE) {
		zc->length = 0;
		zc->recv_skip_hint = inq;
		if (!inq && sock_flag(sk, SOCK_DONE))
		return -EIO;
		return 0;
		}

		mmap_read_lock(current->mm);

		vma = find_vma(current->mm, address);

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