Raphael Norwitz <raphael.norw...@nutanix.com> writes:
>> 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. On the surface it looks similar but the vhost-net code doesn't deal in DeviceState opaques and also has invented a s->watch variable for manually removing gio sources. I'm not sure I'm confident I can re-factor this code and not break something so close to release. > > 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 >>>> >>> >> -- Alex Bennée