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Subject[PATCH 4.14 19/57] net/smc: make sure EPOLLOUT is raised
Date
From: Jason Baron <jbaron@akamai.com>

[ Upstream commit 4651d1802f7063e4d8c0bcad957f46ece0c04024 ]

Currently, we are only explicitly setting SOCK_NOSPACE on a write timeout
for non-blocking sockets. Epoll() edge-trigger mode relies on SOCK_NOSPACE
being set when -EAGAIN is returned to ensure that EPOLLOUT is raised.
Expand the setting of SOCK_NOSPACE to non-blocking sockets as well that can
use SO_SNDTIMEO to adjust their write timeout. This mirrors the behavior
that Eric Dumazet introduced for tcp sockets.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Ursula Braun <ubraun@linux.ibm.com>
Cc: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/smc/smc_tx.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -70,13 +70,11 @@ static int smc_tx_wait_memory(struct smc
DEFINE_WAIT_FUNC(wait, woken_wake_function);
struct smc_connection *conn = &smc->conn;
struct sock *sk = &smc->sk;
- bool noblock;
long timeo;
int rc = 0;

/* similar to sk_stream_wait_memory */
timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
- noblock = timeo ? false : true;
add_wait_queue(sk_sleep(sk), &wait);
while (1) {
sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
@@ -91,8 +89,8 @@ static int smc_tx_wait_memory(struct smc
break;
}
if (!timeo) {
- if (noblock)
- set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
+ /* ensure EPOLLOUT is subsequently generated */
+ set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
rc = -EAGAIN;
break;
}

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