Current Path : /sys/kern/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
Current File : //sys/kern/uipc_cow.c |
/*-- * Copyright (c) 1997, Duke University * All rights reserved. * * Author: * Andrew Gallatin <gallatin@cs.duke.edu> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of Duke University may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY DUKE UNIVERSITY ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DUKE UNIVERSITY BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITSOR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * This is a set of routines for enabling and disabling copy on write * protection for data written into sockets. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD: release/9.1.0/sys/kern/uipc_cow.c 219028 2011-02-25 10:11:01Z netchild $"); #include <sys/param.h> #include <sys/systm.h> #include <sys/sysctl.h> #include <sys/kernel.h> #include <sys/proc.h> #include <sys/lock.h> #include <sys/mutex.h> #include <sys/mbuf.h> #include <sys/sf_buf.h> #include <sys/socketvar.h> #include <sys/uio.h> #include <vm/vm.h> #include <vm/vm_extern.h> #include <vm/vm_param.h> #include <vm/pmap.h> #include <vm/vm_map.h> #include <vm/vm_page.h> #include <vm/vm_object.h> FEATURE(zero_copy_sockets, "Zero copy sockets support"); struct netsend_cow_stats { int attempted; int fail_not_mapped; int fail_sf_buf; int success; int iodone; }; static struct netsend_cow_stats socow_stats; static void socow_iodone(void *addr, void *args); static void socow_iodone(void *addr, void *args) { struct sf_buf *sf; vm_page_t pp; sf = args; pp = sf_buf_page(sf); sf_buf_free(sf); /* remove COW mapping */ vm_page_lock(pp); vm_page_cowclear(pp); vm_page_unwire(pp, 0); /* * Check for the object going away on us. This can * happen since we don't hold a reference to it. * If so, we're responsible for freeing the page. */ if (pp->wire_count == 0 && pp->object == NULL) vm_page_free(pp); vm_page_unlock(pp); socow_stats.iodone++; } int socow_setup(struct mbuf *m0, struct uio *uio) { struct sf_buf *sf; vm_page_t pp; struct iovec *iov; struct vmspace *vmspace; struct vm_map *map; vm_offset_t offset, uva; vm_size_t len; socow_stats.attempted++; vmspace = curproc->p_vmspace; map = &vmspace->vm_map; uva = (vm_offset_t) uio->uio_iov->iov_base; offset = uva & PAGE_MASK; len = PAGE_SIZE - offset; /* * Verify that access to the given address is allowed from user-space. */ if (vm_fault_quick_hold_pages(map, uva, len, VM_PROT_READ, &pp, 1) < 0) { socow_stats.fail_not_mapped++; return(0); } /* * set up COW */ vm_page_lock(pp); if (vm_page_cowsetup(pp) != 0) { vm_page_unhold(pp); vm_page_unlock(pp); return (0); } /* * wire the page for I/O */ vm_page_wire(pp); vm_page_unhold(pp); vm_page_unlock(pp); /* * Allocate an sf buf */ sf = sf_buf_alloc(pp, SFB_CATCH); if (sf == NULL) { vm_page_lock(pp); vm_page_cowclear(pp); vm_page_unwire(pp, 0); /* * Check for the object going away on us. This can * happen since we don't hold a reference to it. * If so, we're responsible for freeing the page. */ if (pp->wire_count == 0 && pp->object == NULL) vm_page_free(pp); vm_page_unlock(pp); socow_stats.fail_sf_buf++; return(0); } /* * attach to mbuf */ MEXTADD(m0, sf_buf_kva(sf), PAGE_SIZE, socow_iodone, (void*)sf_buf_kva(sf), sf, M_RDONLY, EXT_SFBUF); m0->m_len = len; m0->m_data = (caddr_t)sf_buf_kva(sf) + offset; socow_stats.success++; iov = uio->uio_iov; iov->iov_base = (char *)iov->iov_base + m0->m_len; iov->iov_len -= m0->m_len; uio->uio_resid -= m0->m_len; uio->uio_offset += m0->m_len; if (iov->iov_len == 0) { uio->uio_iov++; uio->uio_iovcnt--; } return(m0->m_len); }