> On Nov 29, 2022, at 12:30 AM, Michael S. Tsirkin <m...@redhat.com> wrote: > > On Tue, Nov 29, 2022 at 05:18:58AM +0000, Raphael Norwitz wrote: >>> On Nov 28, 2022, at 11:41 AM, Alex Bennée <alex.ben...@linaro.org> wrote: >>> >>> ..and use for both virtio-user-blk and virtio-user-gpio. This avoids >>> the circular close by deferring shutdown due to disconnection until a >>> later point. virtio-user-blk already had this mechanism in place so >> >> The mechanism was originally copied from virtio-net so we should probably >> fix it there too. AFAICT calling vhost_user_async_close() should work in >> net_vhost_user_event(). >> >> Otherwise the code looks good modulo a few nits. Happy to see the duplicated >> logic is being generalized. > > If you do, separate patch pls and does not have to block this series.
If the series is urgent my comments can be addressed later. Reviewed-by: Raphael Norwitz <raphael.norw...@nutanix.com> > >> >>> generalise it as a vhost-user helper function and use for both blk and >>> gpio devices. >>> >>> While we are at it we also fix up vhost-user-gpio to re-establish the >>> event handler after close down so we can reconnect later. >>> >>> Signed-off-by: Alex Bennée <alex.ben...@linaro.org> >>> --- >>> include/hw/virtio/vhost-user.h | 18 +++++++++ >>> hw/block/vhost-user-blk.c | 41 +++----------------- >>> hw/virtio/vhost-user-gpio.c | 11 +++++- >>> hw/virtio/vhost-user.c | 71 ++++++++++++++++++++++++++++++++++ >>> 4 files changed, 104 insertions(+), 37 deletions(-) >>> >>> diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h >>> index c6e693cd3f..191216a74f 100644 >>> --- a/include/hw/virtio/vhost-user.h >>> +++ b/include/hw/virtio/vhost-user.h >>> @@ -68,4 +68,22 @@ bool vhost_user_init(VhostUserState *user, CharBackend >>> *chr, Error **errp); >>> */ >>> void vhost_user_cleanup(VhostUserState *user); >>> >>> +/** >>> + * vhost_user_async_close() - cleanup vhost-user post connection drop >>> + * @d: DeviceState for the associated device (passed to callback) >>> + * @chardev: the CharBackend associated with the connection >>> + * @vhost: the common vhost device >>> + * @cb: the user callback function to complete the clean-up >>> + * >>> + * This function is used to handle the shutdown of a vhost-user >>> + * connection to a backend. We handle this centrally to make sure we >>> + * do all the steps and handle potential races due to VM shutdowns. >>> + * Once the connection is disabled we call a backhalf to ensure >>> + */ >>> +typedef void (*vu_async_close_fn)(DeviceState *cb); >>> + >>> +void vhost_user_async_close(DeviceState *d, >>> + CharBackend *chardev, struct vhost_dev *vhost, >>> + vu_async_close_fn cb); >>> + >>> #endif >>> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c >>> index 1177064631..aff4d2b8cb 100644 >>> --- a/hw/block/vhost-user-blk.c >>> +++ b/hw/block/vhost-user-blk.c >>> @@ -369,17 +369,10 @@ static void vhost_user_blk_disconnect(DeviceState >>> *dev) >>> vhost_user_blk_stop(vdev); >>> >>> vhost_dev_cleanup(&s->dev); >>> -} >>> >>> -static void vhost_user_blk_chr_closed_bh(void *opaque) >>> -{ >>> - DeviceState *dev = opaque; >>> - VirtIODevice *vdev = VIRTIO_DEVICE(dev); >>> - VHostUserBlk *s = VHOST_USER_BLK(vdev); >>> - >>> - vhost_user_blk_disconnect(dev); >>> + /* Re-instate the event handler for new connections */ >>> qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event, >>> - NULL, opaque, NULL, true); >>> + NULL, dev, NULL, true); >>> } >>> >>> static void vhost_user_blk_event(void *opaque, QEMUChrEvent event) >>> @@ -398,33 +391,9 @@ static void vhost_user_blk_event(void *opaque, >>> QEMUChrEvent event) >>> } >>> break; >>> case CHR_EVENT_CLOSED: >>> - if (!runstate_check(RUN_STATE_SHUTDOWN)) { >>> - /* >>> - * A close event may happen during a read/write, but vhost >>> - * code assumes the vhost_dev remains setup, so delay the >>> - * stop & clear. >>> - */ >>> - AioContext *ctx = qemu_get_current_aio_context(); >>> - >>> - qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL, NULL, >>> - NULL, NULL, false); >>> - aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, >>> opaque); >>> - >>> - /* >>> - * Move vhost device to the stopped state. The vhost-user >>> device >>> - * will be clean up and disconnected in BH. This can be useful >>> in >>> - * the vhost migration code. If disconnect was caught there is >>> an >>> - * option for the general vhost code to get the dev state >>> without >>> - * knowing its type (in this case vhost-user). >>> - * >>> - * FIXME: this is sketchy to be reaching into vhost_dev >>> - * now because we are forcing something that implies we >>> - * have executed vhost_dev_stop() but that won't happen >>> - * until vhost_user_blk_stop() gets called from the bh. >>> - * Really this state check should be tracked locally. >>> - */ >>> - s->dev.started = false; >>> - } >>> + /* defer close until later to avoid circular close */ >>> + vhost_user_async_close(dev, &s->chardev, &s->dev, >>> + vhost_user_blk_disconnect); >>> break; >>> case CHR_EVENT_BREAK: >>> case CHR_EVENT_MUX_IN: >>> diff --git a/hw/virtio/vhost-user-gpio.c b/hw/virtio/vhost-user-gpio.c >>> index 75e28bcd3b..cd76287766 100644 >>> --- a/hw/virtio/vhost-user-gpio.c >>> +++ b/hw/virtio/vhost-user-gpio.c >>> @@ -239,6 +239,8 @@ static int vu_gpio_connect(DeviceState *dev, Error >>> **errp) >>> return 0; >>> } >>> >>> +static void vu_gpio_event(void *opaque, QEMUChrEvent event); >>> + >>> static void vu_gpio_disconnect(DeviceState *dev) >>> { >>> VirtIODevice *vdev = VIRTIO_DEVICE(dev); >>> @@ -251,6 +253,11 @@ static void vu_gpio_disconnect(DeviceState *dev) >>> >>> vu_gpio_stop(vdev); >>> vhost_dev_cleanup(&gpio->vhost_dev); >>> + >>> + /* Re-instate the event handler for new connections */ >>> + qemu_chr_fe_set_handlers(&gpio->chardev, >>> + NULL, NULL, vu_gpio_event, >>> + NULL, dev, NULL, true); >>> } >>> >>> static void vu_gpio_event(void *opaque, QEMUChrEvent event) >>> @@ -268,7 +275,9 @@ static void vu_gpio_event(void *opaque, QEMUChrEvent >>> event) >>> } >>> break; >>> case CHR_EVENT_CLOSED: >>> - vu_gpio_disconnect(dev); >>> + /* defer close until later to avoid circular close */ >>> + vhost_user_async_close(dev, &gpio->chardev, &gpio->vhost_dev, >>> + vu_gpio_disconnect); >>> break; >>> case CHR_EVENT_BREAK: >>> case CHR_EVENT_MUX_IN: >>> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c >>> index abe23d4ebe..8f635844af 100644 >>> --- a/hw/virtio/vhost-user.c >>> +++ b/hw/virtio/vhost-user.c >>> @@ -21,6 +21,7 @@ >>> #include "qemu/error-report.h" >>> #include "qemu/main-loop.h" >>> #include "qemu/sockets.h" >>> +#include "sysemu/runstate.h" >>> #include "sysemu/cryptodev.h" >>> #include "migration/migration.h" >>> #include "migration/postcopy-ram.h" >>> @@ -2670,6 +2671,76 @@ void vhost_user_cleanup(VhostUserState *user) >>> user->chr = NULL; >>> } >>> >> >> nit: Extra space >> >>> + >>> +typedef struct { >>> + vu_async_close_fn cb; >>> + DeviceState *dev; >>> + CharBackend *cd; >>> + struct vhost_dev *vhost; >>> +} VhostAsyncCallback; >>> + >>> +static void vhost_user_async_close_bh(void *opaque) >>> +{ >>> + VhostAsyncCallback *data = opaque; >>> + struct vhost_dev *vhost = data->vhost; >>> + >>> + /* >>> + * If the vhost_dev has been cleared in the meantime there is >>> + * nothing left to do as some other path has completed the >>> + * cleanup. >>> + */ >>> + if (vhost->vdev) { >>> + data->cb(data->dev); >>> + } >>> + >>> + g_free(data); >>> +} >>> + >>> +/* >>> + * We only schedule the work if the machine is running. If suspended >>> + * we want to keep all the in-flight data as is for migration >>> + * purposes. >>> + */ >>> +void vhost_user_async_close(DeviceState *d, >>> + CharBackend *chardev, struct vhost_dev *vhost, >>> + vu_async_close_fn cb) >>> +{ >>> + if (!runstate_check(RUN_STATE_SHUTDOWN)) { >>> + /* >>> + * A close event may happen during a read/write, but vhost >>> + * code assumes the vhost_dev remains setup, so delay the >>> + * stop & clear. >>> + */ >>> + AioContext *ctx = qemu_get_current_aio_context(); >>> + VhostAsyncCallback *data = g_new0(VhostAsyncCallback, 1); >>> + >>> + /* Save data for the callback */ >>> + data->cb = cb; >>> + data->dev = d; >>> + data->cd = chardev; >>> + data->vhost = vhost; >>> + >>> + /* Disable any further notifications on the chardev */ >>> + qemu_chr_fe_set_handlers(chardev, >>> + NULL, NULL, NULL, NULL, NULL, NULL, >>> + false); >>> + >>> + aio_bh_schedule_oneshot(ctx, vhost_user_async_close_bh, data); >>> + >>> + /* >>> + * Move vhost device to the stopped state. The vhost-user device >> >> Not this change’s fault but we should fix up the grammar here i.e. >> s/clean/cleaned/ and probably should be “disconnected in the BH”…etc. >> >>> + * will be clean up and disconnected in BH. This can be useful in >>> + * the vhost migration code. If disconnect was caught there is an >>> + * option for the general vhost code to get the dev state without >>> + * knowing its type (in this case vhost-user). >>> + * >>> + * Note if the vhost device is fully cleared by the time we >>> + * execute the bottom half we won't continue with the cleanup. >>> + */ >>> + vhost->started = false; >>> + } >>> +} >>> + >>> static int vhost_user_dev_start(struct vhost_dev *dev, bool started) >>> { >>> if (!virtio_has_feature(dev->protocol_features, >>> -- >>> 2.34.1 >>> >> >