On Wed, Aug 30, 2023 at 06:37:49PM +0800, Zhenzhong Duan wrote: > From: Yi Liu <yi.l....@intel.com> > > /dev/vfio/devices/vfioX may not exist. In that case it is still possible > to open /dev/char/$major:$minor instead. Add helper function to abstract > the cdev open. > > Suggested-by: Jason Gunthorpe <j...@nvidia.com> > Signed-off-by: Yi Liu <yi.l....@intel.com> > Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com> > --- > MAINTAINERS | 6 ++++ > include/qemu/char_dev.h | 16 +++++++++++ > util/chardev_open.c | 61 +++++++++++++++++++++++++++++++++++++++++
Using the same naming scheme for the .c and .h is strongly desired. > util/meson.build | 1 + > 4 files changed, 84 insertions(+) > create mode 100644 include/qemu/char_dev.h > create mode 100644 util/chardev_open.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 04663fbb6f..74d18593fe 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3372,6 +3372,12 @@ S: Maintained > F: include/qemu/iova-tree.h > F: util/iova-tree.c > > +cdev Open > +M: Yi Liu <yi.l....@intel.com> > +S: Maintained > +F: include/qemu/char_dev.h > +F: util/chardev_open.c > + > diff --git a/util/chardev_open.c b/util/chardev_open.c > new file mode 100644 > index 0000000000..d03e415131 > --- /dev/null > +++ b/util/chardev_open.c > @@ -0,0 +1,61 @@ > +/* > + * Copyright (C) 2023 Intel Corporation. > + * Copyright (c) 2019, Mellanox Technologies. All rights reserved. > + * > + * Authors: Yi Liu <yi.l....@intel.com> > + * > + * This work is licensed under the terms of the GNU GPL, version 2. See > + * the COPYING file in the top-level directory. > + * > + * Copied from > + * https://github.com/linux-rdma/rdma-core/blob/master/util/open_cdev.c > + * > + */ Since this is GPL-2.0-only, IMHO it would be preferrable to keep it out of the util/ directory, as we're aiming to not add further 2.0 only code, except for specific subdirs. This only appears to be used by code under hw/vfio/, whcih is one of the dirs still permitting 2.0-only code. So I think better to keep this file where it is used. > +#ifndef _GNU_SOURCE > +#define _GNU_SOURCE > +#endif This is set globally for building all files in QEMU > +#include "qemu/osdep.h" > +#include "qemu/char_dev.h" > + > +static int open_cdev_internal(const char *path, dev_t cdev) > +{ > + struct stat st; > + int fd; > + > + fd = qemu_open_old(path, O_RDWR); > + if (fd == -1) { > + return -1; > + } > + if (fstat(fd, &st) || !S_ISCHR(st.st_mode) || > + (cdev != 0 && st.st_rdev != cdev)) { > + close(fd); > + return -1; > + } > + return fd; > +} > + > +static int open_cdev_robust(dev_t cdev) > +{ > + char *devpath; g_autofree for this... > + int ret; > + > + /* > + * This assumes that udev is being used and is creating the /dev/char/ > + * symlinks. > + */ > + devpath = g_strdup_printf("/dev/char/%u:%u", major(cdev), minor(cdev)); > + ret = open_cdev_internal(devpath, cdev); > + g_free(devpath); ...avoids the need for g_free, and also avoids the need for the intermediate 'ret' variable. > + return ret; > +} > + > +int open_cdev(const char *devpath, dev_t cdev) > +{ > + int fd; > + > + fd = open_cdev_internal(devpath, cdev); > + if (fd == -1 && cdev != 0) { > + return open_cdev_robust(cdev); > + } > + return fd; > +} > diff --git a/util/meson.build b/util/meson.build > index a375160286..d5313d858f 100644 > --- a/util/meson.build > +++ b/util/meson.build > @@ -107,6 +107,7 @@ if have_block > util_ss.add(files('filemonitor-stub.c')) > endif > util_ss.add(when: 'CONFIG_LINUX', if_true: files('vfio-helpers.c')) > + util_ss.add(when: 'CONFIG_LINUX', if_true: files('chardev_open.c')) > endif > > if cpu == 'aarch64' > -- > 2.34.1 > > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
