From: Eric Dumazet

Date: Fri, 09 Jan 2009 16:42:44 +0100
> David, if you referred to code at line 1374 of net/ipv4/tcp.c, I

quoted text
> believe there is no issue with it. We really want to break from this

> loop if !timeo .

Correct, I agree, and I gave some detailed analysis of this in

another response :-)
> Willy patch makes splice() behaving like tcp_recvmsg(), but we might call

quoted text
> tcp_cleanup_rbuf() several times, with copied=1460 (for each frame processed)

"Like", sure, but not the same since splice() lacks the low-water

and backlog checks.
> I wonder if the right fix should be done in tcp_read_sock() : this is the

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> one who should eat several skbs IMHO, if we want optimal ACK generation.

>

> We break out of its loop at line 1246

>

> if (!desc->count) /* this test is always true */

> 	break;

>

> (__tcp_splice_read() set count to 0, right before calling tcp_read_sock())

>

> So code at line 1246 (tcp_read_sock()) seems wrong, or pessimistic at least.

Yes, that's very odd.

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