From: "Daniel P. Berrangé" <berrange@redhat.com>
To: Lukas Straub <lukasstraub2@web.de>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
qemu-block <qemu-block@nongnu.org>,
"Juan Quintela" <quintela@redhat.com>,
qemu-devel <qemu-devel@nongnu.org>,
"Max Reitz" <mreitz@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v4 1/4] Introduce yank feature
Date: Tue, 16 Jun 2020 15:39:57 +0100 [thread overview]
Message-ID: <20200616143957.GF550360@redhat.com> (raw)
In-Reply-To: <dc2724aead900db8fb3bed0a066f7c7e2654edb0.1590421341.git.lukasstraub2@web.de>
On Mon, May 25, 2020 at 05:44:23PM +0200, Lukas Straub wrote:
> The yank feature allows to recover from hanging qemu by "yanking"
> at various parts. Other qemu systems can register themselves and
> multiple yank functions. Then all yank functions for selected
> instances can be called by the 'yank' out-of-band qmp command.
> Available instances can be queried by a 'query-yank' oob command.
>
> Signed-off-by: Lukas Straub <lukasstraub2@web.de>
> ---
> qapi/misc.json | 45 +++++++++++++
> yank.c | 174 +++++++++++++++++++++++++++++++++++++++++++++++++
> yank.h | 67 +++++++++++++++++++
> 3 files changed, 286 insertions(+)
> create mode 100644 yank.c
> create mode 100644 yank.h
> +void yank_register_function(char *instance_name, YankFn *func, void *opaque)
> +{
> + struct YankInstance *instance;
> + struct YankFuncAndParam *entry;
> +
> + qemu_mutex_lock(&lock);
> + instance = yank_find_instance(instance_name);
> + assert(instance);
> +
> + entry = g_slice_new(struct YankFuncAndParam);
> + entry->func = func;
> + entry->opaque = opaque;
> +
> + QLIST_INSERT_HEAD(&instance->yankfns, entry, next);
> + qemu_mutex_unlock(&lock);
> +}
> +
> +void yank_unregister_function(char *instance_name, YankFn *func, void *opaque)
> +{
> + struct YankInstance *instance;
> + struct YankFuncAndParam *entry;
> +
> + qemu_mutex_lock(&lock);
> + instance = yank_find_instance(instance_name);
> + assert(instance);
> +
> + QLIST_FOREACH(entry, &instance->yankfns, next) {
> + if (entry->func == func && entry->opaque == opaque) {
> + QLIST_REMOVE(entry, next);
> + g_slice_free(struct YankFuncAndParam, entry);
> + qemu_mutex_unlock(&lock);
> + return;
> + }
> + }
> +
> + abort();
> +}
Since the NBD impl no longer needs to register multiple different functions
on the same insance_nane, these methods could be be simplified, to only
accept a single function, instead of keeping a whole list. This would avoid
need to pass a function into the unregister() method at all.
I don't consider this a blocker though, so you pick whether to do this
or not.
> diff --git a/yank.h b/yank.h
> new file mode 100644
> index 0000000000..f1c8743b72
> --- /dev/null
> +++ b/yank.h
> @@ -0,0 +1,67 @@
> +
Missing license header
> +#ifndef YANK_H
> +#define YANK_H
> +
> +typedef void (YankFn) (void *opaque);
> +
> +/**
> + * yank_register_instance: Register a new instance.
> + *
> + * This registers a new instance for yanking. Must be called before any yank
> + * function is registered for this instance.
> + *
> + * This function is thread-safe.
> + *
> + * @instance_name: The globally unique name of the instance.
> + */
> +void yank_register_instance(char *instance_name);
> +
> +/**
> + * yank_unregister_instance: Unregister a instance.
> + *
> + * This unregisters a instance. Must be called only after every yank function
> + * of the instance has been unregistered.
> + *
> + * This function is thread-safe.
> + *
> + * @instance_name: The name of the instance.
> + */
> +void yank_unregister_instance(char *instance_name);
> +
> +/**
> + * yank_register_function: Register a yank function
> + *
> + * This registers a yank function. All limitations of qmp oob commands apply
> + * to the yank function as well.
> + *
> + * This function is thread-safe.
> + *
> + * @instance_name: The name of the instance
> + * @func: The yank function
> + * @opaque: Will be passed to the yank function
> + */
> +void yank_register_function(char *instance_name, YankFn *func, void *opaque);
> +
> +/**
> + * yank_unregister_function: Unregister a yank function
> + *
> + * This unregisters a yank function.
> + *
> + * This function is thread-safe.
> + *
> + * @instance_name: The name of the instance
> + * @func: func that was passed to yank_register_function
> + * @opaque: opaque that was passed to yank_register_function
> + */
> +void yank_unregister_function(char *instance_name, YankFn *func, void *opaque);
> +
> +/**
> + * yank_unregister_function: Generic yank function for iochannel
> + *
> + * This is a generic yank function which will call qio_channel_shutdown on the
> + * provided QIOChannel.
> + *
> + * @opaque: QIOChannel to shutdown
> + */
> +void yank_generic_iochannel(void *opaque);
> +#endif
Regards,
Daniel
--
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next prev parent reply other threads:[~2020-06-16 15:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 15:44 [PATCH v4 0/4] Introduce 'yank' oob qmp command to recover from hanging qemu Lukas Straub
2020-05-25 15:44 ` [PATCH v4 1/4] Introduce yank feature Lukas Straub
2020-06-16 14:39 ` Daniel P. Berrangé [this message]
2020-06-19 14:23 ` Lukas Straub
2020-06-19 16:53 ` Daniel P. Berrangé
2020-06-16 14:49 ` Daniel P. Berrangé
2020-06-17 15:12 ` Stefan Hajnoczi
2020-06-19 16:29 ` Lukas Straub
2020-06-19 16:52 ` Daniel P. Berrangé
2020-06-19 16:59 ` Lukas Straub
2020-05-25 15:44 ` [PATCH v4 2/4] block/nbd.c: Add " Lukas Straub
2020-06-16 14:40 ` Daniel P. Berrangé
2020-06-16 14:44 ` Daniel P. Berrangé
2020-06-19 16:23 ` Lukas Straub
2020-06-17 15:09 ` Stefan Hajnoczi
2020-06-19 18:07 ` Lukas Straub
2020-05-25 15:44 ` [PATCH v4 3/4] chardev/char-socket.c: " Lukas Straub
2020-06-16 14:41 ` Daniel P. Berrangé
2020-05-25 15:44 ` [PATCH v4 4/4] migration: " Lukas Straub
2020-06-16 14:42 ` Daniel P. Berrangé
2020-06-06 19:30 ` [PATCH v4 0/4] Introduce 'yank' oob qmp command to recover from hanging qemu Lukas Straub
2020-06-17 14:41 ` Stefan Hajnoczi
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