path: root/net/ipv4/udp.c
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2018-06-28 09:43:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-06-28 10:40:47 -0700
commita11e1d432b51f63ba698d044441284a661f01144 (patch)
tree9f3c5a10bf0d7f9a342d5fb39c0c35ea14170124 /net/ipv4/udp.c
parentMerge tag 'xfs-4.18-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux (diff)
Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL
The poll() changes were not well thought out, and completely unexplained. They also caused a huge performance regression, because "->poll()" was no longer a trivial file operation that just called down to the underlying file operations, but instead did at least two indirect calls. Indirect calls are sadly slow now with the Spectre mitigation, but the performance problem could at least be largely mitigated by changing the "->get_poll_head()" operation to just have a per-file-descriptor pointer to the poll head instead. That gets rid of one of the new indirections. But that doesn't fix the new complexity that is completely unwarranted for the regular case. The (undocumented) reason for the poll() changes was some alleged AIO poll race fixing, but we don't make the common case slower and more complex for some uncommon special case, so this all really needs way more explanations and most likely a fundamental redesign. [ This revert is a revert of about 30 different commits, not reverted individually because that would just be unnecessarily messy - Linus ] Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/ipv4/udp.c')
1 files changed, 5 insertions, 5 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9bb27df4dac5..24e116ddae79 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2591,7 +2591,7 @@ int compat_udp_getsockopt(struct sock *sk, int level, int optname,
* udp_poll - wait for a UDP event.
* @file - file struct
* @sock - socket
- * @events - events to wait for
+ * @wait - poll table
* This is same as datagram poll, except for the special case of
* blocking sockets. If application is using a blocking fd
@@ -2600,23 +2600,23 @@ int compat_udp_getsockopt(struct sock *sk, int level, int optname,
* but then block when reading it. Add special case code
* to work around these arguably broken applications.
-__poll_t udp_poll_mask(struct socket *sock, __poll_t events)
+__poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait)
- __poll_t mask = datagram_poll_mask(sock, events);
+ __poll_t mask = datagram_poll(file, sock, wait);
struct sock *sk = sock->sk;
if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
/* Check for false positives due to checksum errors */
- if ((mask & EPOLLRDNORM) && !(sock->file->f_flags & O_NONBLOCK) &&
+ if ((mask & EPOLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
!(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)
return mask;
int udp_abort(struct sock *sk, int err)