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![Linus Torvalds](/assets/img/avatar_default.png)
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>
162 lines
3.7 KiB
C
162 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* net/atm/pvc.c - ATM PVC sockets */
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/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */
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#include <linux/net.h> /* struct socket, struct proto_ops */
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#include <linux/atm.h> /* ATM stuff */
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#include <linux/atmdev.h> /* ATM devices */
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#include <linux/errno.h> /* error codes */
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#include <linux/kernel.h> /* printk */
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#include <linux/init.h>
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#include <linux/skbuff.h>
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#include <linux/bitops.h>
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#include <linux/export.h>
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#include <net/sock.h> /* for sock_no_* */
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#include "resources.h" /* devs and vccs */
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#include "common.h" /* common for PVCs and SVCs */
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static int pvc_shutdown(struct socket *sock, int how)
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{
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return 0;
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}
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static int pvc_bind(struct socket *sock, struct sockaddr *sockaddr,
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int sockaddr_len)
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{
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struct sock *sk = sock->sk;
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struct sockaddr_atmpvc *addr;
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struct atm_vcc *vcc;
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int error;
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if (sockaddr_len != sizeof(struct sockaddr_atmpvc))
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return -EINVAL;
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addr = (struct sockaddr_atmpvc *)sockaddr;
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if (addr->sap_family != AF_ATMPVC)
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return -EAFNOSUPPORT;
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lock_sock(sk);
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vcc = ATM_SD(sock);
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if (!test_bit(ATM_VF_HASQOS, &vcc->flags)) {
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error = -EBADFD;
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goto out;
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}
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if (test_bit(ATM_VF_PARTIAL, &vcc->flags)) {
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if (vcc->vpi != ATM_VPI_UNSPEC)
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addr->sap_addr.vpi = vcc->vpi;
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if (vcc->vci != ATM_VCI_UNSPEC)
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addr->sap_addr.vci = vcc->vci;
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}
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error = vcc_connect(sock, addr->sap_addr.itf, addr->sap_addr.vpi,
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addr->sap_addr.vci);
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out:
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release_sock(sk);
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return error;
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}
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static int pvc_connect(struct socket *sock, struct sockaddr *sockaddr,
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int sockaddr_len, int flags)
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{
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return pvc_bind(sock, sockaddr, sockaddr_len);
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}
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static int pvc_setsockopt(struct socket *sock, int level, int optname,
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char __user *optval, unsigned int optlen)
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{
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struct sock *sk = sock->sk;
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int error;
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lock_sock(sk);
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error = vcc_setsockopt(sock, level, optname, optval, optlen);
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release_sock(sk);
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return error;
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}
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static int pvc_getsockopt(struct socket *sock, int level, int optname,
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char __user *optval, int __user *optlen)
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{
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struct sock *sk = sock->sk;
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int error;
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lock_sock(sk);
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error = vcc_getsockopt(sock, level, optname, optval, optlen);
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release_sock(sk);
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return error;
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}
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static int pvc_getname(struct socket *sock, struct sockaddr *sockaddr,
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int peer)
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{
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struct sockaddr_atmpvc *addr;
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struct atm_vcc *vcc = ATM_SD(sock);
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if (!vcc->dev || !test_bit(ATM_VF_ADDR, &vcc->flags))
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return -ENOTCONN;
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addr = (struct sockaddr_atmpvc *)sockaddr;
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memset(addr, 0, sizeof(*addr));
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addr->sap_family = AF_ATMPVC;
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addr->sap_addr.itf = vcc->dev->number;
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addr->sap_addr.vpi = vcc->vpi;
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addr->sap_addr.vci = vcc->vci;
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return sizeof(struct sockaddr_atmpvc);
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}
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static const struct proto_ops pvc_proto_ops = {
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.family = PF_ATMPVC,
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.owner = THIS_MODULE,
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.release = vcc_release,
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.bind = pvc_bind,
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.connect = pvc_connect,
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.socketpair = sock_no_socketpair,
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.accept = sock_no_accept,
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.getname = pvc_getname,
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.poll = vcc_poll,
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.ioctl = vcc_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = vcc_compat_ioctl,
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#endif
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.listen = sock_no_listen,
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.shutdown = pvc_shutdown,
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.setsockopt = pvc_setsockopt,
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.getsockopt = pvc_getsockopt,
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.sendmsg = vcc_sendmsg,
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.recvmsg = vcc_recvmsg,
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.mmap = sock_no_mmap,
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.sendpage = sock_no_sendpage,
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};
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static int pvc_create(struct net *net, struct socket *sock, int protocol,
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int kern)
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{
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if (net != &init_net)
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return -EAFNOSUPPORT;
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sock->ops = &pvc_proto_ops;
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return vcc_create(net, sock, protocol, PF_ATMPVC, kern);
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}
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static const struct net_proto_family pvc_family_ops = {
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.family = PF_ATMPVC,
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.create = pvc_create,
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.owner = THIS_MODULE,
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};
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/*
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* Initialize the ATM PVC protocol family
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*/
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int __init atmpvc_init(void)
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{
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return sock_register(&pvc_family_ops);
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}
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void atmpvc_exit(void)
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{
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sock_unregister(PF_ATMPVC);
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}
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