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authorDavid Gibson <david@gibson.dropbear.id.au>2023-11-07 13:42:42 +1100
committerStefano Brivio <sbrivio@redhat.com>2023-11-07 09:53:58 +0100
commit5a79ba6272814dda72b387ea13b97d1f0e79dbcf (patch)
tree86cc44a8a003e508ad98992ec285faedcefe3670
parent536acab2de70468b3d8e6b5f876576525ce82258 (diff)
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tcp_splice: Don't handle EPOLL_CTL_DEL as part of tcp_splice_epoll_ctl()
tcp_splice_epoll_ctl() removes both sockets from the epoll set if called when conn->flags & CLOSING. This will always happen immediately after setting that flag, since conn_flag_do() makes the call itself. That's also the _only_ time it can happen: we perform the EPOLL_CTL_DEL without clearing the conn->in_epoll flag, meaning that any further calls to tcp_splice_epoll_ctl() would attempt EPOLL_CTL_MOD, which would necessarily fail since the fds are no longer in the epoll. The EPOLL_CTL_DEL path in tcp_splice_epoll_ctl() has essentially zero overlap with anything else the function does, so just move them to be open coded in conn_flag_do(). This does require kernel 2.6.9 or later, in order to pass NULL as the event structure for epoll_ctl(). However, we already require at least 3.13 to allow unprivileged user namespaces. Given that, simply directly perform the EPOLL_CTL_DEL operations from conn_flag_do() rather than unnecessarily multiplexini Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
-rw-r--r--tcp_splice.c12
1 files changed, 4 insertions, 8 deletions
diff --git a/tcp_splice.c b/tcp_splice.c
index 6c4c664..570a8c6 100644
--- a/tcp_splice.c
+++ b/tcp_splice.c
@@ -152,8 +152,10 @@ static void conn_flag_do(const struct ctx *c, struct tcp_splice_conn *conn,
}
}
- if (flag == CLOSING)
- tcp_splice_epoll_ctl(c, conn);
+ if (flag == CLOSING) {
+ epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->a, NULL);
+ epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->b, NULL);
+ }
}
#define conn_flag(c, conn, flag) \
@@ -182,12 +184,6 @@ static int tcp_splice_epoll_ctl(const struct ctx *c,
struct epoll_event ev_b = { .data.u64 = ref_b.u64 };
uint32_t events_a, events_b;
- if (conn->flags & CLOSING) {
- epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->a, &ev_a);
- epoll_ctl(c->epollfd, EPOLL_CTL_DEL, conn->b, &ev_b);
- return 0;
- }
-
tcp_splice_conn_epoll_events(conn->events, &events_a, &events_b);
ev_a.events = events_a;
ev_b.events = events_b;