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Revert "net: simplify sock_poll_wait"

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This reverts commit dd979b4df8.

This broke tcp_poll for SMC fallback: An AF_SMC socket establishes an
internal TCP socket for the initial handshake with the remote peer.
Whenever the SMC connection can not be established this TCP socket is
used as a fallback. All socket operations on the SMC socket are then
forwarded to the TCP socket. In case of poll, the file->private_data
pointer references the SMC socket because the TCP socket has no file
assigned. This causes tcp_poll to wait on the wrong socket.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Karsten Graul
2018-10-23 13:40:39 +02:00
committed by David S. Miller
parent 6b7a02f708
commit 89ab066d42
13 changed files with 22 additions and 16 deletions
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12
include/net/sock.h
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@@ -2059,14 +2059,20 @@ static inline bool skwq_has_sleeper(struct socket_wq *wq)
/**
* sock_poll_wait - place memory barrier behind the poll_wait call.
* @filp: file
* @sock: socket to wait on
* @p: poll_table
*
* See the comments in the wq_has_sleeper function.
*
* Do not derive sock from filp->private_data here. An SMC socket establishes
* an internal TCP socket that is used in the fallback case. All socket
* operations on the SMC socket are then forwarded to the TCP socket. In case of
* poll, the filp->private_data pointer references the SMC socket because the
* TCP socket has no file assigned.
*/
static inline void sock_poll_wait(struct file *filp, poll_table *p)
static inline void sock_poll_wait(struct file *filp, struct socket *sock,
poll_table *p)
{
struct socket *sock = filp->private_data;
if (!poll_does_not_wait(p)) {
poll_wait(filp, &sock->wq->wait, p);
/* We need to be sure we are in sync with the