When using -L with Linux app emulation, there is an issue in
init_paths where Qemu will get lost exploring a directory tree
with a symlink loop in it. This causes Qemu to hang, and
eventually consume all memory in the system.
Qemu's code for pre-exploring the entire directory tree is both
error-prone and slow. Instead, this changes uses faccessat, which
both avoids the symlink loop (since the entire directory space isn't
being explored up front), and likely speeds things up a bit.
Partial credit goes to Richard Henderson, as it was only after staring
at his patch [1] that I wrote mine.
[1] https://patchwork.kernel.org/patch/9512083/
Signed-off-by: Evan Green <evgreen@chromium.org>
---
Since the path() function returns a final path, I used a thread-local
global to contain the glued-together path. From my examination of the
callers of path(), this is sufficient. The thread-localness of it may
not actually be necessary, but it seemed safer. I can remove the __thread
attribute if desired.
---
util/path.c | 159 ++++++++----------------------------------------------------
1 file changed, 21 insertions(+), 138 deletions(-)
diff --git a/util/path.c b/util/path.c
index 7f9fc272fb..b9a0e8ef47 100644
--- a/util/path.c
+++ b/util/path.c
@@ -4,133 +4,13 @@
The assumption is that this area does not change.
*/
#include "qemu/osdep.h"
-#include <sys/param.h>
-#include <dirent.h>
+#include <limits.h>
#include "qemu/cutils.h"
#include "qemu/path.h"
-struct pathelem
-{
- /* Name of this, eg. lib */
- char *name;
- /* Full path name, eg. /usr/gnemul/x86-linux/lib. */
- char *pathname;
- struct pathelem *parent;
- /* Children */
- unsigned int num_entries;
- struct pathelem *entries[0];
-};
-
-static struct pathelem *base;
-
-/* First N chars of S1 match S2, and S2 is N chars long. */
-static int strneq(const char *s1, unsigned int n, const char *s2)
-{
- unsigned int i;
-
- for (i = 0; i < n; i++)
- if (s1[i] != s2[i])
- return 0;
- return s2[i] == 0;
-}
-
-static struct pathelem *add_entry(struct pathelem *root, const char *name,
- unsigned type);
-
-static struct pathelem *new_entry(const char *root,
- struct pathelem *parent,
- const char *name)
-{
- struct pathelem *new = g_malloc(sizeof(*new));
- new->name = g_strdup(name);
- new->pathname = g_strdup_printf("%s/%s", root, name);
- new->num_entries = 0;
- return new;
-}
-
-#define streq(a,b) (strcmp((a), (b)) == 0)
-
-/* Not all systems provide this feature */
-#if defined(DT_DIR) && defined(DT_UNKNOWN) && defined(DT_LNK)
-# define dirent_type(dirent) ((dirent)->d_type)
-# define is_dir_maybe(type) \
- ((type) == DT_DIR || (type) == DT_UNKNOWN || (type) == DT_LNK)
-#else
-# define dirent_type(dirent) (1)
-# define is_dir_maybe(type) (type)
-#endif
-
-static struct pathelem *add_dir_maybe(struct pathelem *path)
-{
- DIR *dir;
-
- if ((dir = opendir(path->pathname)) != NULL) {
- struct dirent *dirent;
-
- while ((dirent = readdir(dir)) != NULL) {
- if (!streq(dirent->d_name,".") && !streq(dirent->d_name,"..")){
- path = add_entry(path, dirent->d_name, dirent_type(dirent));
- }
- }
- closedir(dir);
- }
- return path;
-}
-
-static struct pathelem *add_entry(struct pathelem *root, const char *name,
- unsigned type)
-{
- struct pathelem **e;
-
- root->num_entries++;
-
- root = g_realloc(root, sizeof(*root)
- + sizeof(root->entries[0])*root->num_entries);
- e = &root->entries[root->num_entries-1];
-
- *e = new_entry(root->pathname, root, name);
- if (is_dir_maybe(type)) {
- *e = add_dir_maybe(*e);
- }
-
- return root;
-}
-
-/* This needs to be done after tree is stabilized (ie. no more reallocs!). */
-static void set_parents(struct pathelem *child, struct pathelem *parent)
-{
- unsigned int i;
-
- child->parent = parent;
- for (i = 0; i < child->num_entries; i++)
- set_parents(child->entries[i], child);
-}
-
-/* FIXME: Doesn't handle DIR/.. where DIR is not in emulated dir. */
-static const char *
-follow_path(const struct pathelem *cursor, const char *name)
-{
- unsigned int i, namelen;
-
- name += strspn(name, "/");
- namelen = strcspn(name, "/");
-
- if (namelen == 0)
- return cursor->pathname;
-
- if (strneq(name, namelen, ".."))
- return follow_path(cursor->parent, name + namelen);
-
- if (strneq(name, namelen, "."))
- return follow_path(cursor, name + namelen);
-
- for (i = 0; i < cursor->num_entries; i++)
- if (strneq(name, namelen, cursor->entries[i]->name))
- return follow_path(cursor->entries[i], name + namelen);
-
- /* Not found */
- return NULL;
-}
+static const char *pathprefix;
+int pathprefixfd = -1;
+__thread char gluedpath[PATH_MAX];
void init_paths(const char *prefix)
{
@@ -150,28 +30,31 @@ void init_paths(const char *prefix)
pstrcat(pref_buf, pref_buf_len, "/");
pstrcat(pref_buf, pref_buf_len, prefix);
free(cwd);
- } else
- pstrcpy(pref_buf, sizeof(pref_buf), prefix + 1);
-
- base = new_entry("", NULL, pref_buf);
- base = add_dir_maybe(base);
- if (base->num_entries == 0) {
- g_free(base->pathname);
- g_free(base->name);
- g_free(base);
- base = NULL;
- } else {
- set_parents(base, base);
+ prefix = strdup(pref_buf);
+ if (!prefix) {
+ abort();
+ }
}
+
+ pathprefix = prefix;
+ pathprefixfd = open(pathprefix, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
}
/* Look for path in emulation dir, otherwise return name. */
const char *path(const char *name)
{
+ const char *relname;
/* Only do absolute paths: quick and dirty, but should mostly be OK.
Could do relative by tracking cwd. */
- if (!base || !name || name[0] != '/')
+ if ((pathprefixfd < 0) || !name || name[0] != '/') {
return name;
+ }
+
+ relname = name + strspn(name, "/");
+ if (faccessat(pathprefixfd, relname, R_OK, AT_EACCESS) == 0) {
+ snprintf(gluedpath, sizeof(gluedpath), "%s%s", pathprefix, name);
+ return gluedpath;
+ }
- return follow_path(base, name) ?: name;
+ return name;
}
--
2.13.5
Hi,
This series failed docker-mingw@fedora build test. Please find the testing commands and
their output below. If you have Docker installed, you can probably reproduce it
locally.
Type: series
Message-id: 20180529234409.27023-1-evgreen@chromium.org
Subject: [Qemu-devel] [PATCH] Fix hang with -L and symlink loop
=== TEST SCRIPT BEGIN ===
#!/bin/bash
set -e
git submodule update --init dtc
# Let docker tests dump environment info
export SHOW_ENV=1
export J=8
time make docker-test-mingw@fedora
=== TEST SCRIPT END ===
Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
Switched to a new branch 'test'
b423111c7a Fix hang with -L and symlink loop
=== OUTPUT BEGIN ===
Submodule 'dtc' (git://git.qemu-project.org/dtc.git) registered for path 'dtc'
Cloning into '/var/tmp/patchew-tester-tmp-1qpzctc8/src/dtc'...
Submodule path 'dtc': checked out 'e54388015af1fb4bf04d0bca99caba1074d9cc42'
BUILD fedora
make[1]: Entering directory '/var/tmp/patchew-tester-tmp-1qpzctc8/src'
GEN /var/tmp/patchew-tester-tmp-1qpzctc8/src/docker-src.2018-05-29-21.30.42.1357/qemu.tar
Cloning into '/var/tmp/patchew-tester-tmp-1qpzctc8/src/docker-src.2018-05-29-21.30.42.1357/qemu.tar.vroot'...
done.
Checking out files: 30% (1907/6176)
Checking out files: 31% (1915/6176)
Checking out files: 32% (1977/6176)
Checking out files: 33% (2039/6176)
Checking out files: 34% (2100/6176)
Checking out files: 35% (2162/6176)
Checking out files: 36% (2224/6176)
Checking out files: 37% (2286/6176)
Checking out files: 38% (2347/6176)
Checking out files: 39% (2409/6176)
Checking out files: 40% (2471/6176)
Checking out files: 41% (2533/6176)
Checking out files: 42% (2594/6176)
Checking out files: 43% (2656/6176)
Checking out files: 44% (2718/6176)
Checking out files: 45% (2780/6176)
Checking out files: 46% (2841/6176)
Checking out files: 47% (2903/6176)
Checking out files: 48% (2965/6176)
Checking out files: 49% (3027/6176)
Checking out files: 49% (3032/6176)
Checking out files: 50% (3088/6176)
Checking out files: 51% (3150/6176)
Checking out files: 52% (3212/6176)
Checking out files: 53% (3274/6176)
Checking out files: 54% (3336/6176)
Checking out files: 55% (3397/6176)
Checking out files: 56% (3459/6176)
Checking out files: 57% (3521/6176)
Checking out files: 58% (3583/6176)
Checking out files: 59% (3644/6176)
Checking out files: 60% (3706/6176)
Checking out files: 61% (3768/6176)
Checking out files: 62% (3830/6176)
Checking out files: 63% (3891/6176)
Checking out files: 64% (3953/6176)
Checking out files: 65% (4015/6176)
Checking out files: 66% (4077/6176)
Checking out files: 67% (4138/6176)
Checking out files: 68% (4200/6176)
Checking out files: 69% (4262/6176)
Checking out files: 70% (4324/6176)
Checking out files: 71% (4385/6176)
Checking out files: 72% (4447/6176)
Checking out files: 73% (4509/6176)
Checking out files: 74% (4571/6176)
Checking out files: 75% (4632/6176)
Checking out files: 76% (4694/6176)
Checking out files: 77% (4756/6176)
Checking out files: 78% (4818/6176)
Checking out files: 79% (4880/6176)
Checking out files: 80% (4941/6176)
Checking out files: 81% (5003/6176)
Checking out files: 82% (5065/6176)
Checking out files: 83% (5127/6176)
Checking out files: 84% (5188/6176)
Checking out files: 85% (5250/6176)
Checking out files: 86% (5312/6176)
Checking out files: 87% (5374/6176)
Checking out files: 88% (5435/6176)
Checking out files: 89% (5497/6176)
Checking out files: 90% (5559/6176)
Checking out files: 91% (5621/6176)
Checking out files: 92% (5682/6176)
Checking out files: 93% (5744/6176)
Checking out files: 94% (5806/6176)
Checking out files: 95% (5868/6176)
Checking out files: 96% (5929/6176)
Checking out files: 97% (5991/6176)
Checking out files: 98% (6053/6176)
Checking out files: 99% (6115/6176)
Checking out files: 100% (6176/6176)
Checking out files: 100% (6176/6176), done.
Your branch is up-to-date with 'origin/test'.
Submodule 'dtc' (git://git.qemu-project.org/dtc.git) registered for path 'dtc'
Cloning into '/var/tmp/patchew-tester-tmp-1qpzctc8/src/docker-src.2018-05-29-21.30.42.1357/qemu.tar.vroot/dtc'...
Submodule path 'dtc': checked out 'e54388015af1fb4bf04d0bca99caba1074d9cc42'
Submodule 'ui/keycodemapdb' (git://git.qemu.org/keycodemapdb.git) registered for path 'ui/keycodemapdb'
Cloning into '/var/tmp/patchew-tester-tmp-1qpzctc8/src/docker-src.2018-05-29-21.30.42.1357/qemu.tar.vroot/ui/keycodemapdb'...
Submodule path 'ui/keycodemapdb': checked out '6b3d716e2b6472eb7189d3220552280ef3d832ce'
COPY RUNNER
RUN test-mingw in qemu:fedora
Packages installed:
PyYAML-3.12-5.fc27.x86_64
SDL2-devel-2.0.7-2.fc27.x86_64
bc-1.07.1-3.fc27.x86_64
bison-3.0.4-8.fc27.x86_64
bluez-libs-devel-5.48-3.fc27.x86_64
brlapi-devel-0.6.6-8.fc27.x86_64
bzip2-1.0.6-24.fc27.x86_64
bzip2-devel-1.0.6-24.fc27.x86_64
ccache-3.3.6-1.fc27.x86_64
clang-5.0.1-5.fc27.x86_64
device-mapper-multipath-devel-0.7.1-9.git847cc43.fc27.x86_64
findutils-4.6.0-16.fc27.x86_64
flex-2.6.1-5.fc27.x86_64
gcc-7.3.1-5.fc27.x86_64
gcc-c++-7.3.1-5.fc27.x86_64
gettext-0.19.8.1-12.fc27.x86_64
git-2.14.3-3.fc27.x86_64
glib2-devel-2.54.3-2.fc27.x86_64
glusterfs-api-devel-3.12.7-1.fc27.x86_64
gnutls-devel-3.5.18-2.fc27.x86_64
gtk3-devel-3.22.26-2.fc27.x86_64
hostname-3.18-4.fc27.x86_64
libaio-devel-0.3.110-9.fc27.x86_64
libasan-7.3.1-5.fc27.x86_64
libattr-devel-2.4.47-21.fc27.x86_64
libcap-devel-2.25-7.fc27.x86_64
libcap-ng-devel-0.7.8-5.fc27.x86_64
libcurl-devel-7.55.1-10.fc27.x86_64
libfdt-devel-1.4.6-1.fc27.x86_64
libpng-devel-1.6.31-1.fc27.x86_64
librbd-devel-12.2.4-1.fc27.x86_64
libssh2-devel-1.8.0-5.fc27.x86_64
libubsan-7.3.1-5.fc27.x86_64
libusbx-devel-1.0.21-4.fc27.x86_64
libxml2-devel-2.9.7-1.fc27.x86_64
llvm-5.0.1-6.fc27.x86_64
lzo-devel-2.08-11.fc27.x86_64
make-4.2.1-4.fc27.x86_64
mingw32-SDL-1.2.15-9.fc27.noarch
mingw32-bzip2-1.0.6-9.fc27.noarch
mingw32-curl-7.54.1-2.fc27.noarch
mingw32-glib2-2.54.1-1.fc27.noarch
mingw32-gmp-6.1.2-2.fc27.noarch
mingw32-gnutls-3.5.13-2.fc27.noarch
mingw32-gtk2-2.24.31-4.fc27.noarch
mingw32-gtk3-3.22.16-1.fc27.noarch
mingw32-libjpeg-turbo-1.5.1-3.fc27.noarch
mingw32-libpng-1.6.29-2.fc27.noarch
mingw32-libssh2-1.8.0-3.fc27.noarch
mingw32-libtasn1-4.13-1.fc27.noarch
mingw32-nettle-3.3-3.fc27.noarch
mingw32-pixman-0.34.0-3.fc27.noarch
mingw32-pkg-config-0.28-9.fc27.x86_64
mingw64-SDL-1.2.15-9.fc27.noarch
mingw64-bzip2-1.0.6-9.fc27.noarch
mingw64-curl-7.54.1-2.fc27.noarch
mingw64-glib2-2.54.1-1.fc27.noarch
mingw64-gmp-6.1.2-2.fc27.noarch
mingw64-gnutls-3.5.13-2.fc27.noarch
mingw64-gtk2-2.24.31-4.fc27.noarch
mingw64-gtk3-3.22.16-1.fc27.noarch
mingw64-libjpeg-turbo-1.5.1-3.fc27.noarch
mingw64-libpng-1.6.29-2.fc27.noarch
mingw64-libssh2-1.8.0-3.fc27.noarch
mingw64-libtasn1-4.13-1.fc27.noarch
mingw64-nettle-3.3-3.fc27.noarch
mingw64-pixman-0.34.0-3.fc27.noarch
mingw64-pkg-config-0.28-9.fc27.x86_64
ncurses-devel-6.0-13.20170722.fc27.x86_64
nettle-devel-3.4-1.fc27.x86_64
nss-devel-3.36.0-1.0.fc27.x86_64
numactl-devel-2.0.11-5.fc27.x86_64
package libjpeg-devel is not installed
perl-5.26.1-403.fc27.x86_64
pixman-devel-0.34.0-4.fc27.x86_64
python3-3.6.2-13.fc27.x86_64
snappy-devel-1.1.4-5.fc27.x86_64
sparse-0.5.1-2.fc27.x86_64
spice-server-devel-0.14.0-1.fc27.x86_64
systemtap-sdt-devel-3.2-3.fc27.x86_64
tar-1.29-7.fc27.x86_64
usbredir-devel-0.7.1-5.fc27.x86_64
virglrenderer-devel-0.6.0-3.20170210git76b3da97b.fc27.x86_64
vte3-devel-0.36.5-5.fc27.x86_64
which-2.21-4.fc27.x86_64
xen-devel-4.9.1-5.fc27.x86_64
zlib-devel-1.2.11-4.fc27.x86_64
Environment variables:
TARGET_LIST=
PACKAGES=ccache gettext git tar PyYAML sparse flex bison python3 bzip2 hostname gcc gcc-c++ llvm clang make perl which bc findutils glib2-devel libaio-devel pixman-devel zlib-devel libfdt-devel libasan libubsan bluez-libs-devel brlapi-devel bzip2-devel device-mapper-multipath-devel glusterfs-api-devel gnutls-devel gtk3-devel libattr-devel libcap-devel libcap-ng-devel libcurl-devel libjpeg-devel libpng-devel librbd-devel libssh2-devel libusbx-devel libxml2-devel lzo-devel ncurses-devel nettle-devel nss-devel numactl-devel SDL2-devel snappy-devel spice-server-devel systemtap-sdt-devel usbredir-devel virglrenderer-devel vte3-devel xen-devel mingw32-pixman mingw32-glib2 mingw32-gmp mingw32-SDL mingw32-pkg-config mingw32-gtk2 mingw32-gtk3 mingw32-gnutls mingw32-nettle mingw32-libtasn1 mingw32-libjpeg-turbo mingw32-libpng mingw32-curl mingw32-libssh2 mingw32-bzip2 mingw64-pixman mingw64-glib2 mingw64-gmp mingw64-SDL mingw64-pkg-config mingw64-gtk2 mingw64-gtk3 mingw64-gnutls mingw64-nettle mingw64-libtasn1 mingw64-libjpeg-turbo mingw64-libpng mingw64-curl mingw64-libssh2 mingw64-bzip2
J=8
V=
HOSTNAME=52e017a2d846
DEBUG=
SHOW_ENV=1
PWD=/
HOME=/root
CCACHE_DIR=/var/tmp/ccache
DISTTAG=f27container
QEMU_CONFIGURE_OPTS=--python=/usr/bin/python3
FGC=f27
TEST_DIR=/tmp/qemu-test
SHLVL=1
FEATURES=mingw clang pyyaml asan dtc
PATH=/usr/lib/ccache:/usr/lib64/ccache:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
MAKEFLAGS= -j8
EXTRA_CONFIGURE_OPTS=
_=/usr/bin/env
Configure options:
--enable-werror --target-list=x86_64-softmmu,aarch64-softmmu --prefix=/tmp/qemu-test/install --python=/usr/bin/python3 --cross-prefix=x86_64-w64-mingw32- --enable-trace-backends=simple --enable-gnutls --enable-nettle --enable-curl --enable-vnc --enable-bzip2 --enable-guest-agent --with-sdlabi=1.2 --with-gtkabi=2.0
Install prefix /tmp/qemu-test/install
BIOS directory /tmp/qemu-test/install
firmware path /tmp/qemu-test/install/share/qemu-firmware
binary directory /tmp/qemu-test/install
library directory /tmp/qemu-test/install/lib
module directory /tmp/qemu-test/install/lib
libexec directory /tmp/qemu-test/install/libexec
include directory /tmp/qemu-test/install/include
config directory /tmp/qemu-test/install
local state directory queried at runtime
Windows SDK no
Source path /tmp/qemu-test/src
GIT binary git
GIT submodules
C compiler x86_64-w64-mingw32-gcc
Host C compiler cc
C++ compiler x86_64-w64-mingw32-g++
Objective-C compiler clang
ARFLAGS rv
CFLAGS -O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -g
QEMU_CFLAGS -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/pixman-1 -I$(SRC_PATH)/dtc/libfdt -Werror -DHAS_LIBSSH2_SFTP_FSYNC -mms-bitfields -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/glib-2.0 -I/usr/x86_64-w64-mingw32/sys-root/mingw/lib/glib-2.0/include -I/usr/x86_64-w64-mingw32/sys-root/mingw/include -m64 -mcx16 -mthreads -D__USE_MINGW_ANSI_STDIO=1 -DWIN32_LEAN_AND_MEAN -DWINVER=0x501 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -Wexpansion-to-defined -Wendif-labels -Wno-shift-negative-value -Wno-missing-include-dirs -Wempty-body -Wnested-externs -Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-declaration -Wold-style-definition -Wtype-limits -fstack-protector-strong -I/usr/x86_64-w64-mingw32/sys-root/mingw/include -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/p11-kit-1 -I/usr/x86_64-w64-mingw32/sys-root/mingw/include -I/usr/x86_64-w64-mingw32/sys-root/mingw/include -I/usr/x86_64-w64-mingw32/sys-root/mingw/include/libpng16
LDFLAGS -Wl,--nxcompat -Wl,--no-seh -Wl,--dynamicbase -Wl,--warn-common -m64 -g
QEMU_LDFLAGS -L$(BUILD_DIR)/dtc/libfdt
make make
install install
python /usr/bin/python3 -B
smbd /usr/sbin/smbd
module support no
host CPU x86_64
host big endian no
target list x86_64-softmmu aarch64-softmmu
gprof enabled no
sparse enabled no
strip binaries yes
profiler no
static build no
SDL support yes (1.2.15)
GTK support yes (2.24.31)
GTK GL support no
VTE support no
TLS priority NORMAL
GNUTLS support yes
GNUTLS rnd yes
libgcrypt no
libgcrypt kdf no
nettle yes (3.3)
nettle kdf yes
libtasn1 yes
curses support no
virgl support no
curl support yes
mingw32 support yes
Audio drivers dsound
Block whitelist (rw)
Block whitelist (ro)
VirtFS support no
Multipath support no
VNC support yes
VNC SASL support no
VNC JPEG support yes
VNC PNG support yes
xen support no
brlapi support no
bluez support no
Documentation no
PIE no
vde support no
netmap support no
Linux AIO support no
ATTR/XATTR support no
Install blobs yes
KVM support no
HAX support yes
HVF support no
WHPX support no
TCG support yes
TCG debug enabled no
TCG interpreter no
malloc trim support no
RDMA support no
fdt support git
membarrier no
preadv support no
fdatasync no
madvise no
posix_madvise no
posix_memalign no
libcap-ng support no
vhost-net support no
vhost-crypto support no
vhost-scsi support no
vhost-vsock support no
vhost-user support no
Trace backends simple
Trace output file trace-<pid>
spice support no
rbd support no
xfsctl support no
smartcard support no
libusb no
usb net redir no
OpenGL support no
OpenGL dmabufs no
libiscsi support no
libnfs support no
build guest agent yes
QGA VSS support no
QGA w32 disk info yes
QGA MSI support no
seccomp support no
coroutine backend win32
coroutine pool yes
debug stack usage no
crypto afalg no
GlusterFS support no
gcov gcov
gcov enabled no
TPM support yes
libssh2 support yes
TPM passthrough no
TPM emulator no
QOM debugging yes
Live block migration yes
lzo support no
snappy support no
bzip2 support yes
NUMA host support no
libxml2 no
tcmalloc support no
jemalloc support no
avx2 optimization yes
replication support yes
VxHS block device no
capstone no
WARNING: Use of GTK 2.0 is deprecated and will be removed in
WARNING: future releases. Please switch to using GTK 3.0
WARNING: Use of SDL 1.2 is deprecated and will be removed in
WARNING: future releases. Please switch to using SDL 2.0
GEN x86_64-softmmu/config-devices.mak.tmp
GEN aarch64-softmmu/config-devices.mak.tmp
GEN config-host.h
GEN qemu-options.def
GEN qapi-gen
GEN trace/generated-tcg-tracers.h
GEN trace/generated-helpers-wrappers.h
GEN trace/generated-helpers.h
GEN trace/generated-helpers.c
GEN module_block.h
GEN aarch64-softmmu/config-devices.mak
GEN x86_64-softmmu/config-devices.mak
GEN ui/input-keymap-atset1-to-qcode.c
GEN ui/input-keymap-linux-to-qcode.c
GEN ui/input-keymap-qcode-to-atset1.c
GEN ui/input-keymap-qcode-to-atset2.c
GEN ui/input-keymap-qcode-to-atset3.c
GEN ui/input-keymap-qcode-to-linux.c
GEN ui/input-keymap-qcode-to-qnum.c
GEN ui/input-keymap-qnum-to-qcode.c
GEN ui/input-keymap-qcode-to-sun.c
GEN ui/input-keymap-usb-to-qcode.c
GEN ui/input-keymap-win32-to-qcode.c
GEN ui/input-keymap-x11-to-qcode.c
GEN ui/input-keymap-xorgevdev-to-qcode.c
GEN ui/input-keymap-xorgkbd-to-qcode.c
GEN ui/input-keymap-xorgxquartz-to-qcode.c
GEN ui/input-keymap-xorgxwin-to-qcode.c
GEN tests/test-qapi-gen
GEN trace-root.h
GEN util/trace.h
GEN crypto/trace.h
GEN io/trace.h
GEN migration/trace.h
GEN block/trace.h
GEN chardev/trace.h
GEN hw/block/trace.h
GEN hw/block/dataplane/trace.h
GEN hw/char/trace.h
GEN hw/intc/trace.h
GEN hw/net/trace.h
GEN hw/rdma/trace.h
GEN hw/rdma/vmw/trace.h
GEN hw/virtio/trace.h
GEN hw/audio/trace.h
GEN hw/misc/trace.h
GEN hw/misc/macio/trace.h
GEN hw/usb/trace.h
GEN hw/scsi/trace.h
GEN hw/nvram/trace.h
GEN hw/display/trace.h
GEN hw/input/trace.h
GEN hw/timer/trace.h
GEN hw/dma/trace.h
GEN hw/sparc/trace.h
GEN hw/sparc64/trace.h
GEN hw/sd/trace.h
GEN hw/isa/trace.h
GEN hw/mem/trace.h
GEN hw/i386/trace.h
GEN hw/i386/xen/trace.h
GEN hw/9pfs/trace.h
GEN hw/ppc/trace.h
GEN hw/pci/trace.h
GEN hw/pci-host/trace.h
GEN hw/s390x/trace.h
GEN hw/vfio/trace.h
GEN hw/acpi/trace.h
GEN hw/arm/trace.h
GEN hw/alpha/trace.h
GEN hw/hppa/trace.h
GEN hw/xen/trace.h
GEN hw/ide/trace.h
GEN hw/tpm/trace.h
GEN ui/trace.h
GEN audio/trace.h
GEN net/trace.h
GEN target/arm/trace.h
GEN target/i386/trace.h
GEN target/mips/trace.h
GEN target/sparc/trace.h
GEN target/s390x/trace.h
GEN target/ppc/trace.h
GEN qom/trace.h
GEN linux-user/trace.h
GEN qapi/trace.h
GEN accel/tcg/trace.h
GEN accel/kvm/trace.h
GEN nbd/trace.h
GEN scsi/trace.h
GEN trace-root.c
GEN util/trace.c
GEN crypto/trace.c
GEN io/trace.c
GEN migration/trace.c
GEN block/trace.c
GEN chardev/trace.c
GEN hw/block/trace.c
GEN hw/block/dataplane/trace.c
GEN hw/char/trace.c
GEN hw/intc/trace.c
GEN hw/net/trace.c
GEN hw/rdma/trace.c
GEN hw/rdma/vmw/trace.c
GEN hw/virtio/trace.c
GEN hw/audio/trace.c
GEN hw/misc/trace.c
GEN hw/misc/macio/trace.c
GEN hw/usb/trace.c
GEN hw/scsi/trace.c
GEN hw/nvram/trace.c
GEN hw/display/trace.c
GEN hw/input/trace.c
GEN hw/timer/trace.c
GEN hw/dma/trace.c
GEN hw/sparc/trace.c
GEN hw/sparc64/trace.c
GEN hw/sd/trace.c
GEN hw/isa/trace.c
GEN hw/mem/trace.c
GEN hw/i386/trace.c
GEN hw/i386/xen/trace.c
GEN hw/9pfs/trace.c
GEN hw/ppc/trace.c
GEN hw/pci/trace.c
GEN hw/pci-host/trace.c
GEN hw/s390x/trace.c
GEN hw/vfio/trace.c
GEN hw/acpi/trace.c
GEN hw/arm/trace.c
GEN hw/alpha/trace.c
GEN hw/hppa/trace.c
GEN hw/xen/trace.c
GEN hw/ide/trace.c
GEN hw/tpm/trace.c
GEN ui/trace.c
GEN audio/trace.c
GEN net/trace.c
GEN target/arm/trace.c
GEN target/i386/trace.c
GEN target/mips/trace.c
GEN target/sparc/trace.c
GEN target/s390x/trace.c
GEN target/ppc/trace.c
GEN qom/trace.c
GEN linux-user/trace.c
GEN qapi/trace.c
GEN accel/tcg/trace.c
GEN accel/kvm/trace.c
GEN nbd/trace.c
GEN scsi/trace.c
GEN config-all-devices.mak
DEP /tmp/qemu-test/src/dtc/tests/dumptrees.c
DEP /tmp/qemu-test/src/dtc/tests/trees.S
DEP /tmp/qemu-test/src/dtc/tests/testutils.c
DEP /tmp/qemu-test/src/dtc/tests/value-labels.c
DEP /tmp/qemu-test/src/dtc/tests/asm_tree_dump.c
DEP /tmp/qemu-test/src/dtc/tests/truncated_property.c
DEP /tmp/qemu-test/src/dtc/tests/check_path.c
DEP /tmp/qemu-test/src/dtc/tests/overlay_bad_fixup.c
DEP /tmp/qemu-test/src/dtc/tests/subnode_iterate.c
DEP /tmp/qemu-test/src/dtc/tests/overlay.c
DEP /tmp/qemu-test/src/dtc/tests/property_iterate.c
DEP /tmp/qemu-test/src/dtc/tests/integer-expressions.c
DEP /tmp/qemu-test/src/dtc/tests/utilfdt_test.c
DEP /tmp/qemu-test/src/dtc/tests/path_offset_aliases.c
DEP /tmp/qemu-test/src/dtc/tests/add_subnode_with_nops.c
DEP /tmp/qemu-test/src/dtc/tests/dtbs_equal_unordered.c
DEP /tmp/qemu-test/src/dtc/tests/dtb_reverse.c
DEP /tmp/qemu-test/src/dtc/tests/dtbs_equal_ordered.c
DEP /tmp/qemu-test/src/dtc/tests/extra-terminating-null.c
DEP /tmp/qemu-test/src/dtc/tests/incbin.c
DEP /tmp/qemu-test/src/dtc/tests/boot-cpuid.c
DEP /tmp/qemu-test/src/dtc/tests/phandle_format.c
DEP /tmp/qemu-test/src/dtc/tests/path-references.c
DEP /tmp/qemu-test/src/dtc/tests/references.c
DEP /tmp/qemu-test/src/dtc/tests/string_escapes.c
DEP /tmp/qemu-test/src/dtc/tests/propname_escapes.c
DEP /tmp/qemu-test/src/dtc/tests/appendprop2.c
DEP /tmp/qemu-test/src/dtc/tests/del_node.c
DEP /tmp/qemu-test/src/dtc/tests/appendprop1.c
DEP /tmp/qemu-test/src/dtc/tests/del_property.c
DEP /tmp/qemu-test/src/dtc/tests/setprop.c
DEP /tmp/qemu-test/src/dtc/tests/set_name.c
DEP /tmp/qemu-test/src/dtc/tests/open_pack.c
DEP /tmp/qemu-test/src/dtc/tests/rw_tree1.c
DEP /tmp/qemu-test/src/dtc/tests/nopulate.c
DEP /tmp/qemu-test/src/dtc/tests/mangle-layout.c
DEP /tmp/qemu-test/src/dtc/tests/move_and_save.c
DEP /tmp/qemu-test/src/dtc/tests/sw_tree1.c
DEP /tmp/qemu-test/src/dtc/tests/nop_node.c
DEP /tmp/qemu-test/src/dtc/tests/nop_property.c
DEP /tmp/qemu-test/src/dtc/tests/setprop_inplace.c
DEP /tmp/qemu-test/src/dtc/tests/stringlist.c
DEP /tmp/qemu-test/src/dtc/tests/notfound.c
DEP /tmp/qemu-test/src/dtc/tests/addr_size_cells.c
DEP /tmp/qemu-test/src/dtc/tests/sized_cells.c
DEP /tmp/qemu-test/src/dtc/tests/char_literal.c
DEP /tmp/qemu-test/src/dtc/tests/get_alias.c
DEP /tmp/qemu-test/src/dtc/tests/node_offset_by_compatible.c
DEP /tmp/qemu-test/src/dtc/tests/node_check_compatible.c
DEP /tmp/qemu-test/src/dtc/tests/node_offset_by_phandle.c
DEP /tmp/qemu-test/src/dtc/tests/node_offset_by_prop_value.c
DEP /tmp/qemu-test/src/dtc/tests/parent_offset.c
DEP /tmp/qemu-test/src/dtc/tests/supernode_atdepth_offset.c
DEP /tmp/qemu-test/src/dtc/tests/get_path.c
DEP /tmp/qemu-test/src/dtc/tests/get_phandle.c
DEP /tmp/qemu-test/src/dtc/tests/getprop.c
DEP /tmp/qemu-test/src/dtc/tests/get_name.c
DEP /tmp/qemu-test/src/dtc/tests/path_offset.c
DEP /tmp/qemu-test/src/dtc/tests/subnode_offset.c
DEP /tmp/qemu-test/src/dtc/tests/find_property.c
DEP /tmp/qemu-test/src/dtc/tests/root_node.c
DEP /tmp/qemu-test/src/dtc/tests/get_mem_rsv.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_overlay.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_addresses.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_empty_tree.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_strerror.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_rw.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_sw.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_wip.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt.c
DEP /tmp/qemu-test/src/dtc/libfdt/fdt_ro.c
DEP /tmp/qemu-test/src/dtc/util.c
DEP /tmp/qemu-test/src/dtc/fdtoverlay.c
DEP /tmp/qemu-test/src/dtc/fdtput.c
DEP /tmp/qemu-test/src/dtc/fdtget.c
DEP /tmp/qemu-test/src/dtc/fdtdump.c
LEX convert-dtsv0-lexer.lex.c
DEP /tmp/qemu-test/src/dtc/srcpos.c
BISON dtc-parser.tab.c
LEX dtc-lexer.lex.c
DEP /tmp/qemu-test/src/dtc/treesource.c
DEP /tmp/qemu-test/src/dtc/livetree.c
DEP /tmp/qemu-test/src/dtc/fstree.c
DEP /tmp/qemu-test/src/dtc/flattree.c
DEP /tmp/qemu-test/src/dtc/dtc.c
DEP /tmp/qemu-test/src/dtc/data.c
DEP /tmp/qemu-test/src/dtc/checks.c
DEP convert-dtsv0-lexer.lex.c
DEP dtc-parser.tab.c
DEP dtc-lexer.lex.c
CHK version_gen.h
UPD version_gen.h
DEP /tmp/qemu-test/src/dtc/util.c
CC libfdt/fdt.o
CC libfdt/fdt_wip.o
CC libfdt/fdt_strerror.o
CC libfdt/fdt_ro.o
CC libfdt/fdt_sw.o
CC libfdt/fdt_rw.o
CC libfdt/fdt_empty_tree.o
CC libfdt/fdt_addresses.o
CC libfdt/fdt_overlay.o
AR libfdt/libfdt.a
x86_64-w64-mingw32-ar: creating libfdt/libfdt.a
a - libfdt/fdt.o
a - libfdt/fdt_ro.o
a - libfdt/fdt_wip.o
a - libfdt/fdt_sw.o
a - libfdt/fdt_rw.o
a - libfdt/fdt_strerror.o
a - libfdt/fdt_empty_tree.o
a - libfdt/fdt_addresses.o
a - libfdt/fdt_overlay.o
RC version.o
GEN qga/qapi-generated/qapi-gen
CC qapi/qapi-builtin-types.o
CC qapi/qapi-types.o
CC qapi/qapi-types-block-core.o
CC qapi/qapi-types-char.o
CC qapi/qapi-types-block.o
CC qapi/qapi-types-common.o
CC qapi/qapi-types-crypto.o
CC qapi/qapi-types-introspect.o
CC qapi/qapi-types-job.o
CC qapi/qapi-types-migration.o
CC qapi/qapi-types-misc.o
CC qapi/qapi-types-net.o
CC qapi/qapi-types-rocker.o
CC qapi/qapi-types-run-state.o
CC qapi/qapi-types-sockets.o
CC qapi/qapi-types-tpm.o
CC qapi/qapi-types-trace.o
CC qapi/qapi-types-transaction.o
CC qapi/qapi-types-ui.o
CC qapi/qapi-builtin-visit.o
CC qapi/qapi-visit.o
CC qapi/qapi-visit-block-core.o
CC qapi/qapi-visit-char.o
CC qapi/qapi-visit-block.o
CC qapi/qapi-visit-common.o
CC qapi/qapi-visit-crypto.o
CC qapi/qapi-visit-introspect.o
CC qapi/qapi-visit-job.o
CC qapi/qapi-visit-migration.o
CC qapi/qapi-visit-misc.o
CC qapi/qapi-visit-net.o
CC qapi/qapi-visit-rocker.o
CC qapi/qapi-visit-run-state.o
CC qapi/qapi-visit-sockets.o
CC qapi/qapi-visit-tpm.o
CC qapi/qapi-visit-trace.o
CC qapi/qapi-visit-transaction.o
CC qapi/qapi-visit-ui.o
CC qapi/qapi-events.o
CC qapi/qapi-events-block-core.o
CC qapi/qapi-events-block.o
CC qapi/qapi-events-char.o
CC qapi/qapi-events-common.o
CC qapi/qapi-events-crypto.o
CC qapi/qapi-events-introspect.o
CC qapi/qapi-events-job.o
CC qapi/qapi-events-migration.o
CC qapi/qapi-events-misc.o
CC qapi/qapi-events-net.o
CC qapi/qapi-events-rocker.o
CC qapi/qapi-events-run-state.o
CC qapi/qapi-events-sockets.o
CC qapi/qapi-events-tpm.o
CC qapi/qapi-events-trace.o
CC qapi/qapi-events-transaction.o
CC qapi/qapi-events-ui.o
CC qapi/qapi-introspect.o
CC qapi/qapi-visit-core.o
CC qapi/qapi-dealloc-visitor.o
CC qapi/qobject-input-visitor.o
CC qapi/qobject-output-visitor.o
CC qapi/qmp-registry.o
CC qapi/qmp-dispatch.o
CC qapi/string-input-visitor.o
CC qapi/string-output-visitor.o
CC qapi/opts-visitor.o
CC qapi/qapi-clone-visitor.o
CC qapi/qmp-event.o
CC qapi/qapi-util.o
CC qobject/qnull.o
CC qobject/qnum.o
CC qobject/qstring.o
CC qobject/qdict.o
CC qobject/qlist.o
CC qobject/qbool.o
CC qobject/qlit.o
CC qobject/qjson.o
CC qobject/qobject.o
CC qobject/json-lexer.o
CC qobject/json-streamer.o
CC qobject/json-parser.o
CC trace/simple.o
CC trace/control.o
CC trace/qmp.o
CC util/osdep.o
CC util/cutils.o
CC util/unicode.o
CC util/qemu-timer-common.o
CC util/bufferiszero.o
CC util/lockcnt.o
CC util/aiocb.o
CC util/async.o
CC util/aio-wait.o
CC util/thread-pool.o
CC util/qemu-timer.o
CC util/iohandler.o
CC util/main-loop.o
CC util/aio-win32.o
CC util/event_notifier-win32.o
CC util/oslib-win32.o
CC util/qemu-thread-win32.o
CC util/envlist.o
CC util/path.o
CC util/module.o
CC util/host-utils.o
CC util/bitmap.o
CC util/bitops.o
CC util/hbitmap.o
CC util/fifo8.o
CC util/acl.o
CC util/cacheinfo.o
CC util/error.o
CC util/qemu-error.o
CC util/id.o
CC util/iov.o
CC util/qemu-config.o
CC util/qemu-sockets.o
CC util/uri.o
CC util/notify.o
CC util/qemu-option.o
CC util/qemu-progress.o
CC util/keyval.o
CC util/hexdump.o
CC util/crc32c.o
CC util/uuid.o
CC util/throttle.o
CC util/getauxval.o
CC util/readline.o
CC util/rcu.o
CC util/qemu-coroutine.o
CC util/qemu-coroutine-lock.o
CC util/qemu-coroutine-io.o
CC util/qemu-coroutine-sleep.o
CC util/coroutine-win32.o
CC util/buffer.o
CC util/timed-average.o
CC util/base64.o
CC util/log.o
CC util/pagesize.o
CC util/qdist.o
CC util/qht.o
CC util/range.o
CC util/stats64.o
CC util/systemd.o
CC util/iova-tree.o
CC trace-root.o
CC util/trace.o
CC crypto/trace.o
CC io/trace.o
CC migration/trace.o
CC block/trace.o
CC hw/block/trace.o
CC chardev/trace.o
CC hw/block/dataplane/trace.o
CC hw/char/trace.o
CC hw/net/trace.o
CC hw/intc/trace.o
CC hw/rdma/trace.o
CC hw/rdma/vmw/trace.o
CC hw/virtio/trace.o
CC hw/audio/trace.o
CC hw/misc/trace.o
CC hw/misc/macio/trace.o
CC hw/usb/trace.o
CC hw/scsi/trace.o
CC hw/nvram/trace.o
CC hw/display/trace.o
CC hw/input/trace.o
CC hw/timer/trace.o
CC hw/dma/trace.o
CC hw/sparc/trace.o
CC hw/sparc64/trace.o
CC hw/sd/trace.o
CC hw/isa/trace.o
CC hw/mem/trace.o
CC hw/i386/trace.o
CC hw/i386/xen/trace.o
CC hw/9pfs/trace.o
CC hw/ppc/trace.o
CC hw/pci/trace.o
CC hw/pci-host/trace.o
CC hw/s390x/trace.o
CC hw/vfio/trace.o
CC hw/acpi/trace.o
CC hw/arm/trace.o
CC hw/alpha/trace.o
CC hw/hppa/trace.o
CC hw/xen/trace.o
/tmp/qemu-test/src/util/path.c: In function 'init_paths':
/tmp/qemu-test/src/util/path.c:40:48: error: 'O_DIRECTORY' undeclared (first use in this function); did you mean 'DOF_DIRECTORY'?
pathprefixfd = open(pathprefix, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
^~~~~~~~~~~
DOF_DIRECTORY
/tmp/qemu-test/src/util/path.c:40:48: note: each undeclared identifier is reported only once for each function it appears in
/tmp/qemu-test/src/util/path.c:40:62: error: 'O_CLOEXEC' undeclared (first use in this function); did you mean '_S_IEXEC'?
pathprefixfd = open(pathprefix, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
^~~~~~~~~
_S_IEXEC
/tmp/qemu-test/src/util/path.c: In function 'path':
/tmp/qemu-test/src/util/path.c:54:9: error: implicit declaration of function 'faccessat'; did you mean 'access'? [-Werror=implicit-function-declaration]
if (faccessat(pathprefixfd, relname, R_OK, AT_EACCESS) == 0) {
^~~~~~~~~
access
/tmp/qemu-test/src/util/path.c:54:9: error: nested extern declaration of 'faccessat' [-Werror=nested-externs]
/tmp/qemu-test/src/util/path.c:54:48: error: 'AT_EACCESS' undeclared (first use in this function); did you mean 'EACCES'?
if (faccessat(pathprefixfd, relname, R_OK, AT_EACCESS) == 0) {
^~~~~~~~~~
EACCES
cc1: all warnings being treated as errors
make: *** [/tmp/qemu-test/src/rules.mak:66: util/path.o] Error 1
make: *** Waiting for unfinished jobs....
Traceback (most recent call last):
File "./tests/docker/docker.py", line 407, in <module>
sys.exit(main())
File "./tests/docker/docker.py", line 404, in main
return args.cmdobj.run(args, argv)
File "./tests/docker/docker.py", line 261, in run
return Docker().run(argv, args.keep, quiet=args.quiet)
File "./tests/docker/docker.py", line 229, in run
quiet=quiet)
File "./tests/docker/docker.py", line 147, in _do_check
return subprocess.check_call(self._command + cmd, **kwargs)
File "/usr/lib64/python2.7/subprocess.py", line 186, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['docker', 'run', '--label', 'com.qemu.instance.uuid=1bda302e63a911e89e1252540069c830', '-u', '0', '--security-opt', 'seccomp=unconfined', '--rm', '--net=none', '-e', 'TARGET_LIST=', '-e', 'EXTRA_CONFIGURE_OPTS=', '-e', 'V=', '-e', 'J=8', '-e', 'DEBUG=', '-e', 'SHOW_ENV=1', '-e', 'CCACHE_DIR=/var/tmp/ccache', '-v', '/root/.cache/qemu-docker-ccache:/var/tmp/ccache:z', '-v', '/var/tmp/patchew-tester-tmp-1qpzctc8/src/docker-src.2018-05-29-21.30.42.1357:/var/tmp/qemu:z,ro', 'qemu:fedora', '/var/tmp/qemu/run', 'test-mingw']' returned non-zero exit status 2
make[1]: *** [tests/docker/Makefile.include:129: docker-run] Error 1
make[1]: Leaving directory '/var/tmp/patchew-tester-tmp-1qpzctc8/src'
make: *** [tests/docker/Makefile.include:163: docker-run-test-mingw@fedora] Error 2
real 1m36.313s
user 0m4.749s
sys 0m4.020s
=== OUTPUT END ===
Test command exited with code: 2
---
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On 05/29/2018 04:44 PM, Evan Green wrote: > When using -L with Linux app emulation, there is an issue in > init_paths where Qemu will get lost exploring a directory tree > with a symlink loop in it. This causes Qemu to hang, and > eventually consume all memory in the system. > > Qemu's code for pre-exploring the entire directory tree is both > error-prone and slow. Instead, this changes uses faccessat, which > both avoids the symlink loop (since the entire directory space isn't > being explored up front), and likely speeds things up a bit. > > Partial credit goes to Richard Henderson, as it was only after staring > at his patch [1] that I wrote mine. > > [1] https://patchwork.kernel.org/patch/9512083/ > > Signed-off-by: Evan Green <evgreen@chromium.org> > --- I like this as an improvement on the current situation. Perhaps folks do like this a bit better than my more invasive patch. > +int pathprefixfd = -1; > +__thread char gluedpath[PATH_MAX]; static for both, otherwise, Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
On 30 May 2018 at 21:50, Richard Henderson <richard.henderson@linaro.org> wrote: > On 05/29/2018 04:44 PM, Evan Green wrote: >> When using -L with Linux app emulation, there is an issue in >> init_paths where Qemu will get lost exploring a directory tree >> with a symlink loop in it. This causes Qemu to hang, and >> eventually consume all memory in the system. >> >> Qemu's code for pre-exploring the entire directory tree is both >> error-prone and slow. Instead, this changes uses faccessat, which >> both avoids the symlink loop (since the entire directory space isn't >> being explored up front), and likely speeds things up a bit. >> >> Partial credit goes to Richard Henderson, as it was only after staring >> at his patch [1] that I wrote mine. >> >> [1] https://patchwork.kernel.org/patch/9512083/ >> >> Signed-off-by: Evan Green <evgreen@chromium.org> >> --- > > I like this as an improvement on the current situation. > Perhaps folks do like this a bit better than my more invasive patch. It seems to me to have the same problem as your patch does, which is that we now have a file descriptor which belongs not to the guest but to QEMU, but we make no effort to hide it from the guest, and so for instance code like that xinetd "close every fd above 2" loop will break us. This probably is overall better than the current situation, though, since it will only kick in if you use -L. But if we're going to fix this, I think I preferred your patch. thanks -- PMM
On 05/31/2018 08:26 AM, Peter Maydell wrote: > On 30 May 2018 at 21:50, Richard Henderson <richard.henderson@linaro.org> wrote: >> On 05/29/2018 04:44 PM, Evan Green wrote: >>> When using -L with Linux app emulation, there is an issue in >>> init_paths where Qemu will get lost exploring a directory tree >>> with a symlink loop in it. This causes Qemu to hang, and >>> eventually consume all memory in the system. >>> >>> Qemu's code for pre-exploring the entire directory tree is both >>> error-prone and slow. Instead, this changes uses faccessat, which >>> both avoids the symlink loop (since the entire directory space isn't >>> being explored up front), and likely speeds things up a bit. >>> >>> Partial credit goes to Richard Henderson, as it was only after staring >>> at his patch [1] that I wrote mine. >>> >>> [1] https://patchwork.kernel.org/patch/9512083/ >>> >>> Signed-off-by: Evan Green <evgreen@chromium.org> >>> --- >> >> I like this as an improvement on the current situation. >> Perhaps folks do like this a bit better than my more invasive patch. > > It seems to me to have the same problem as your patch does, > which is that we now have a file descriptor which belongs > not to the guest but to QEMU, but we make no effort to > hide it from the guest, and so for instance code like that > xinetd "close every fd above 2" loop will break us. Yes. I've thought about doing more explicit managing of guest fd's, but it's a big job to re-organize that. r~
On 31 May 2018 at 17:32, Richard Henderson <richard.henderson@linaro.org> wrote: > On 05/31/2018 08:26 AM, Peter Maydell wrote: >> On 30 May 2018 at 21:50, Richard Henderson <richard.henderson@linaro.org> wrote: >>> On 05/29/2018 04:44 PM, Evan Green wrote: >>>> When using -L with Linux app emulation, there is an issue in >>>> init_paths where Qemu will get lost exploring a directory tree >>>> with a symlink loop in it. This causes Qemu to hang, and >>>> eventually consume all memory in the system. >>>> >>>> Qemu's code for pre-exploring the entire directory tree is both >>>> error-prone and slow. Instead, this changes uses faccessat, which >>>> both avoids the symlink loop (since the entire directory space isn't >>>> being explored up front), and likely speeds things up a bit. >>>> >>>> Partial credit goes to Richard Henderson, as it was only after staring >>>> at his patch [1] that I wrote mine. >>>> >>>> [1] https://patchwork.kernel.org/patch/9512083/ >>>> >>>> Signed-off-by: Evan Green <evgreen@chromium.org> >>>> --- >>> >>> I like this as an improvement on the current situation. >>> Perhaps folks do like this a bit better than my more invasive patch. >> >> It seems to me to have the same problem as your patch does, >> which is that we now have a file descriptor which belongs >> not to the guest but to QEMU, but we make no effort to >> hide it from the guest, and so for instance code like that >> xinetd "close every fd above 2" loop will break us. > > Yes. I've thought about doing more explicit managing of guest fd's, but it's a > big job to re-organize that. I think my current opinion is that it's probably OK to have the "our internal fd is visible to the guest" problem for the case where the user specifies -L, at least for now. We're probably causing more problems by not allowing -L to point at trees with symlinks than by misbehaving if the application closes it. We should just leave ourselves a suitable TODO note or something. As I say, I prefer your patch to this one overall, if you wanted to address the minor issues from the last round of review and respin it. thanks -- PMM
On Thu, May 31, 2018 at 9:44 AM Peter Maydell <peter.maydell@linaro.org> wrote: > > On 31 May 2018 at 17:32, Richard Henderson <richard.henderson@linaro.org> wrote: > > On 05/31/2018 08:26 AM, Peter Maydell wrote: > >> On 30 May 2018 at 21:50, Richard Henderson <richard.henderson@linaro.org> wrote: > >>> On 05/29/2018 04:44 PM, Evan Green wrote: > >>>> When using -L with Linux app emulation, there is an issue in > >>>> init_paths where Qemu will get lost exploring a directory tree > >>>> with a symlink loop in it. This causes Qemu to hang, and > >>>> eventually consume all memory in the system. > >>>> > >>>> Qemu's code for pre-exploring the entire directory tree is both > >>>> error-prone and slow. Instead, this changes uses faccessat, which > >>>> both avoids the symlink loop (since the entire directory space isn't > >>>> being explored up front), and likely speeds things up a bit. > >>>> > >>>> Partial credit goes to Richard Henderson, as it was only after staring > >>>> at his patch [1] that I wrote mine. > >>>> > >>>> [1] https://patchwork.kernel.org/patch/9512083/ > >>>> > >>>> Signed-off-by: Evan Green <evgreen@chromium.org> > >>>> --- > >>> > >>> I like this as an improvement on the current situation. > >>> Perhaps folks do like this a bit better than my more invasive patch. > >> > >> It seems to me to have the same problem as your patch does, > >> which is that we now have a file descriptor which belongs > >> not to the guest but to QEMU, but we make no effort to > >> hide it from the guest, and so for instance code like that > >> xinetd "close every fd above 2" loop will break us. > > > > Yes. I've thought about doing more explicit managing of guest fd's, but it's a > > big job to re-organize that. > > I think my current opinion is that it's probably OK to have the > "our internal fd is visible to the guest" problem for the case > where the user specifies -L, at least for now. We're probably > causing more problems by not allowing -L to point at trees with > symlinks than by misbehaving if the application closes it. > We should just leave ourselves a suitable TODO note or something. > > As I say, I prefer your patch to this one overall, if you > wanted to address the minor issues from the last round of > review and respin it. > That sounds good to me. Richard, would you mind CCing me on your next spin of the patch? I'm not on the main list. Thanks, -Evan > thanks > -- PMM
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