Eric Lee / smarc-fsl-linux-kernel

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Commit 5456f09aaf88731e16dbcea7522cb330b6846415

Authored by Eric Dumazet
Committed by David S. Miller
1 parent 67426b756c
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

af_unix: fix unix_dgram_poll() behavior for EPOLLOUT event 

Alban Crequy reported a problem with connected dgram af_unix sockets and
provided a test program. epoll() would miss to send an EPOLLOUT event
when a thread unqueues a packet from the other peer, making its receive
queue not full.

This is because unix_dgram_poll() fails to call sock_poll_wait(file,
&unix_sk(other)->peer_wait, wait);
if the socket is not writeable at the time epoll_ctl(ADD) is called.

We must call sock_poll_wait(), regardless of 'writable' status, so that
epoll can be notified later of states changes.

Misc: avoids testing twice (sk->sk_shutdown & RCV_SHUTDOWN)

Reported-by: Alban Crequy <alban.crequy@collabora.co.uk>
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Showing 1 changed file with 9 additions and 15 deletions Side-by-side Diff

... ... @@ -2074,13 +2074,12 @@
2074 2074 if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
2075 2075 mask |= POLLERR;
2076 2076 if (sk->sk_shutdown & RCV_SHUTDOWN)
2077   - mask |= POLLRDHUP;
  2077 + mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2078 2078 if (sk->sk_shutdown == SHUTDOWN_MASK)
2079 2079 mask |= POLLHUP;
2080 2080  
2081 2081 /* readable? */
2082   - if (!skb_queue_empty(&sk->sk_receive_queue) ||
2083   - (sk->sk_shutdown & RCV_SHUTDOWN))
  2082 + if (!skb_queue_empty(&sk->sk_receive_queue))
2084 2083 mask |= POLLIN | POLLRDNORM;
2085 2084  
2086 2085 /* Connection-based need to check for termination and startup */
2087 2086  
2088 2087  
... ... @@ -2092,20 +2091,15 @@
2092 2091 return mask;
2093 2092 }
2094 2093  
2095   - /* writable? */
2096 2094 writable = unix_writable(sk);
2097   - if (writable) {
2098   - other = unix_peer_get(sk);
2099   - if (other) {
2100   - if (unix_peer(other) != sk) {
2101   - sock_poll_wait(file, &unix_sk(other)->peer_wait,
2102   - wait);
2103   - if (unix_recvq_full(other))
2104   - writable = 0;
2105   - }
2106   -
2107   - sock_put(other);
  2095 + other = unix_peer_get(sk);
  2096 + if (other) {
  2097 + if (unix_peer(other) != sk) {
  2098 + sock_poll_wait(file, &unix_sk(other)->peer_wait, wait);
  2099 + if (unix_recvq_full(other))
  2100 + writable = 0;
2108 2101 }
  2102 + sock_put(other);
2109 2103 }
2110 2104  
2111 2105 if (writable)