688bbd5b76
to information from a single process causes hangs. Specifically, this fixes problems (hangs) with concurrent ps commands, when the system is under heavy memory load. Reviewed by: davidg
348 lines
8.1 KiB
C
348 lines
8.1 KiB
C
/*
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* Copyright (c) 1993 Jan-Simon Pendry
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* Copyright (c) 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)procfs_subr.c 8.4 (Berkeley) 1/27/94
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*
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* $Id: procfs_subr.c,v 1.8 1996/06/18 05:15:59 dyson Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/time.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/malloc.h>
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#include <miscfs/procfs/procfs.h>
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static struct pfsnode *pfshead;
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static int pfsvplock;
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/*
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* allocate a pfsnode/vnode pair. the vnode is
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* referenced, but not locked.
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*
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* the pid, pfs_type, and mount point uniquely
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* identify a pfsnode. the mount point is needed
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* because someone might mount this filesystem
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* twice.
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*
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* all pfsnodes are maintained on a singly-linked
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* list. new nodes are only allocated when they cannot
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* be found on this list. entries on the list are
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* removed when the vfs reclaim entry is called.
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*
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* a single lock is kept for the entire list. this is
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* needed because the getnewvnode() function can block
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* waiting for a vnode to become free, in which case there
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* may be more than one process trying to get the same
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* vnode. this lock is only taken if we are going to
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* call getnewvnode, since the kernel itself is single-threaded.
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*
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* if an entry is found on the list, then call vget() to
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* take a reference. this is done because there may be
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* zero references to it and so it needs to removed from
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* the vnode free list.
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*/
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int
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procfs_allocvp(mp, vpp, pid, pfs_type)
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struct mount *mp;
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struct vnode **vpp;
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long pid;
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pfstype pfs_type;
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{
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int error;
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struct pfsnode *pfs;
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struct pfsnode **pp;
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loop:
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for (pfs = pfshead; pfs != 0; pfs = pfs->pfs_next) {
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if (pfs->pfs_pid == pid &&
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pfs->pfs_type == pfs_type &&
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PFSTOV(pfs)->v_mount == mp) {
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if (vget(pfs->pfs_vnode, 0))
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goto loop;
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*vpp = pfs->pfs_vnode;
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return (0);
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}
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}
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/*
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* otherwise lock the vp list while we call getnewvnode
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* since that can block.
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*/
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if (pfsvplock & PROCFS_LOCKED) {
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pfsvplock |= PROCFS_WANT;
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(void) tsleep((caddr_t) &pfsvplock, PINOD, "pfsavp", 0);
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goto loop;
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}
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pfsvplock |= PROCFS_LOCKED;
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/*
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* Do the MALLOC before the getnewvnode since doing so afterward
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* might cause a bogus v_data pointer to get dereferenced
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* elsewhere if MALLOC should block.
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*/
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MALLOC(pfs, struct pfsnode *, sizeof(struct pfsnode), M_TEMP, M_WAITOK);
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error = getnewvnode(VT_PROCFS, mp, procfs_vnodeop_p, vpp);
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if (error) {
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FREE(pfs, M_TEMP);
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goto out;
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}
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(*vpp)->v_data = pfs;
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pfs->pfs_next = 0;
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pfs->pfs_pid = (pid_t) pid;
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pfs->pfs_type = pfs_type;
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pfs->pfs_vnode = *vpp;
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pfs->pfs_flags = 0;
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pfs->pfs_lockowner = 0;
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pfs->pfs_fileno = PROCFS_FILENO(pid, pfs_type);
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switch (pfs_type) {
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case Proot: /* /proc = dr-xr-xr-x */
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pfs->pfs_mode = (VREAD|VEXEC) |
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(VREAD|VEXEC) >> 3 |
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(VREAD|VEXEC) >> 6;
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break;
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case Pproc:
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pfs->pfs_mode = (VREAD|VEXEC) |
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(VREAD|VEXEC) >> 3 |
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(VREAD|VEXEC) >> 6;
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break;
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case Pfile:
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pfs->pfs_mode = (VREAD|VWRITE);
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break;
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case Pmem:
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pfs->pfs_mode = (VREAD|VWRITE) |
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(VREAD) >> 3;;
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break;
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case Pregs:
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pfs->pfs_mode = (VREAD|VWRITE);
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break;
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case Pfpregs:
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pfs->pfs_mode = (VREAD|VWRITE);
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break;
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case Pctl:
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pfs->pfs_mode = (VWRITE);
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break;
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case Ptype:
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case Pmap:
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case Pstatus:
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pfs->pfs_mode = (VREAD) |
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(VREAD >> 3) |
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(VREAD >> 6);
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break;
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case Pnote:
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pfs->pfs_mode = (VWRITE);
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break;
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case Pnotepg:
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pfs->pfs_mode = (VWRITE);
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break;
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default:
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panic("procfs_allocvp");
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}
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/* add to procfs vnode list */
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for (pp = &pfshead; *pp; pp = &(*pp)->pfs_next)
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continue;
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*pp = pfs;
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out:
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pfsvplock &= ~PROCFS_LOCKED;
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if (pfsvplock & PROCFS_WANT) {
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pfsvplock &= ~PROCFS_WANT;
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wakeup((caddr_t) &pfsvplock);
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}
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return (error);
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}
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int
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procfs_freevp(vp)
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struct vnode *vp;
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{
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struct pfsnode **pfspp;
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struct pfsnode *pfs = VTOPFS(vp);
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for (pfspp = &pfshead; *pfspp != 0; pfspp = &(*pfspp)->pfs_next) {
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if (*pfspp == pfs) {
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*pfspp = pfs->pfs_next;
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break;
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}
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}
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FREE(vp->v_data, M_TEMP);
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vp->v_data = 0;
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return (0);
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}
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int
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procfs_rw(ap)
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struct vop_read_args *ap;
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{
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struct vnode *vp = ap->a_vp;
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struct uio *uio = ap->a_uio;
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struct proc *curp = uio->uio_procp;
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struct pfsnode *pfs = VTOPFS(vp);
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struct proc *p;
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int rtval;
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p = PFIND(pfs->pfs_pid);
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if (p == 0)
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return (EINVAL);
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while (pfs->pfs_lockowner) {
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tsleep(&pfs->pfs_lockowner, PRIBIO, "pfslck", 0);
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}
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pfs->pfs_lockowner = curproc->p_pid;
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switch (pfs->pfs_type) {
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case Pnote:
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case Pnotepg:
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rtval = procfs_donote(curp, p, pfs, uio);
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break;
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case Pregs:
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rtval = procfs_doregs(curp, p, pfs, uio);
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break;
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case Pfpregs:
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rtval = procfs_dofpregs(curp, p, pfs, uio);
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break;
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case Pctl:
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rtval = procfs_doctl(curp, p, pfs, uio);
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break;
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case Pstatus:
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rtval = procfs_dostatus(curp, p, pfs, uio);
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break;
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case Pmap:
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rtval = procfs_domap(curp, p, pfs, uio);
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break;
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case Pmem:
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rtval = procfs_domem(curp, p, pfs, uio);
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break;
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case Ptype:
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rtval = procfs_dotype(curp, p, pfs, uio);
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break;
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default:
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rtval = EOPNOTSUPP;
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break;
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}
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pfs->pfs_lockowner = 0;
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wakeup(&pfs->pfs_lockowner);
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return rtval;
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}
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/*
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* Get a string from userland into (buf). Strip a trailing
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* nl character (to allow easy access from the shell).
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* The buffer should be *buflenp + 1 chars long. vfs_getuserstr
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* will automatically add a nul char at the end.
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*
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* Returns 0 on success or the following errors
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*
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* EINVAL: file offset is non-zero.
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* EMSGSIZE: message is longer than kernel buffer
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* EFAULT: user i/o buffer is not addressable
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*/
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int
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vfs_getuserstr(uio, buf, buflenp)
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struct uio *uio;
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char *buf;
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int *buflenp;
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{
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int xlen;
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int error;
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if (uio->uio_offset != 0)
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return (EINVAL);
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xlen = *buflenp;
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/* must be able to read the whole string in one go */
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if (xlen < uio->uio_resid)
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return (EMSGSIZE);
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xlen = uio->uio_resid;
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error = uiomove(buf, xlen, uio);
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if (error)
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return (error);
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/* allow multiple writes without seeks */
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uio->uio_offset = 0;
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/* cleanup string and remove trailing newline */
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buf[xlen] = '\0';
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xlen = strlen(buf);
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if (xlen > 0 && buf[xlen-1] == '\n')
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buf[--xlen] = '\0';
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*buflenp = xlen;
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return (0);
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}
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vfs_namemap_t *
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vfs_findname(nm, buf, buflen)
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vfs_namemap_t *nm;
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char *buf;
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int buflen;
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{
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for (; nm->nm_name; nm++)
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if (bcmp(buf, (char *) nm->nm_name, buflen+1) == 0)
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return (nm);
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return (0);
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}
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