From 42a7dff4637492563216d2160f99283fa5ab393d Mon Sep 17 00:00:00 2001 From: ad Date: Sun, 18 Feb 2007 20:03:44 +0000 Subject: [PATCH] procfs_map(): - Drop the target's vm_map lock before calling uiomove(). We could deadlock if inspecting /proc/curproc/map. - If the vm_map might have changed, restart the operation, but give up after 250 retries if the map keeps changing. XXX This is not ideal. --- sys/miscfs/procfs/procfs_map.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/sys/miscfs/procfs/procfs_map.c b/sys/miscfs/procfs/procfs_map.c index 454b39f1b2d1..62ad9837e0e0 100644 --- a/sys/miscfs/procfs/procfs_map.c +++ b/sys/miscfs/procfs/procfs_map.c @@ -1,4 +1,4 @@ -/* $NetBSD: procfs_map.c,v 1.29 2007/02/17 22:31:44 pavel Exp $ */ +/* $NetBSD: procfs_map.c,v 1.30 2007/02/18 20:03:44 ad Exp $ */ /* * Copyright (c) 1993 @@ -76,7 +76,7 @@ */ #include -__KERNEL_RCSID(0, "$NetBSD: procfs_map.c,v 1.29 2007/02/17 22:31:44 pavel Exp $"); +__KERNEL_RCSID(0, "$NetBSD: procfs_map.c,v 1.30 2007/02/18 20:03:44 ad Exp $"); #include #include @@ -113,7 +113,7 @@ procfs_domap(struct lwp *curl, struct proc *p, struct pfsnode *pfs, struct uio *uio, int linuxmode) { size_t len; - int error; + int error, retries; struct vmspace *vm; struct vm_map *map; struct vm_map_entry *entry; @@ -123,6 +123,8 @@ procfs_domap(struct lwp *curl, struct proc *p, struct pfsnode *pfs, struct vattr va; dev_t dev; long fileid; + unsigned timestamp; + struct uio savuio; if (uio->uio_rw != UIO_READ) return (EOPNOTSUPP); @@ -146,12 +148,20 @@ procfs_domap(struct lwp *curl, struct proc *p, struct pfsnode *pfs, } map = &vm->vm_map; + memcpy(&savuio, uio, sizeof(savuio)); + retries = 0; vm_map_lock_read(map); + restart: for (entry = map->header.next; ((uio->uio_resid > 0) && (entry != &map->header)); entry = entry->next) { + if (retries > 250) { + error = EWOULDBLOCK; + break; + } + if (UVM_ET_ISSUBMAP(entry)) continue; @@ -205,9 +215,27 @@ procfs_domap(struct lwp *curl, struct proc *p, struct pfsnode *pfs, error = EFBIG; break; } + + timestamp = map->timestamp; + vm_map_unlock_read(map); error = uiomove(mebuffer, len, uio); + vm_map_lock_read(map); if (error) break; + + if (timestamp != map->timestamp) { + /* + * The map may have changed, so restart. We + * make an ugly assumption about uiomove() + * and the vm_map timestamp: it will never + * fall back to copyout_vmspace() because + * we are copying out to curproc. + */ + KASSERT(uio->uio_vmspace == curproc->p_vmspace); + retries++; + memcpy(uio, &savuio, sizeof(*uio)); + goto restart; + } } vm_map_unlock_read(map);