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Re: [Qemu-devel] [PATCH v2 3/6] char: add a QEMU_CHAR_FEATURE_GCONTEXT f
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v2 3/6] char: add a QEMU_CHAR_FEATURE_GCONTEXT flag |
Date: |
Mon, 03 Dec 2018 08:20:34 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
This one needs review by a chardev guy, with an eye on its use in the
next patch. Paolo?
Marc-André Lureau <address@hidden> writes:
> The feature should be set if the chardev is able to switch
> GMainContext. Callers that want to put a chardev in a different thread
> context can/should check this capabilities.
>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
> include/chardev/char.h | 3 +++
> chardev/char.c | 11 +++++++++++
> 2 files changed, 14 insertions(+)
>
> diff --git a/include/chardev/char.h b/include/chardev/char.h
> index 7becd8c80c..014566c3de 100644
> --- a/include/chardev/char.h
> +++ b/include/chardev/char.h
> @@ -47,6 +47,9 @@ typedef enum {
> QEMU_CHAR_FEATURE_FD_PASS,
> /* Whether replay or record mode is enabled */
> QEMU_CHAR_FEATURE_REPLAY,
> + /* Whether the gcontext can be changed after calling
> + * qemu_chr_be_update_read_handlers() */
> + QEMU_CHAR_FEATURE_GCONTEXT,
>
> QEMU_CHAR_FEATURE_LAST,
> } ChardevFeature;
> diff --git a/chardev/char.c b/chardev/char.c
> index 7f07a1bfbd..b5ee58b7d2 100644
> --- a/chardev/char.c
> +++ b/chardev/char.c
> @@ -196,6 +196,8 @@ void qemu_chr_be_update_read_handlers(Chardev *s,
> s->gcontext = context;
> if (cc->chr_update_read_handler) {
> cc->chr_update_read_handler(s);
> + } else if (s->gcontext) {
> + error_report("switching context isn't supported by this chardev");
Code smell: error_report() without returning failure.
If it's truly an error, then the function should fail. We'd still need
to decide how: error_report() and return -1, or error_setg().
Except if it's a programming error; then we should assert().
If it's not an error, it's probably a warning, and we should use
warn_report().
> }
> }
>
> @@ -240,6 +242,15 @@ static void char_init(Object *obj)
>
> chr->logfd = -1;
> qemu_mutex_init(&chr->chr_write_lock);
> +
> + /*
> + * Assume if chr_update_read_handler is implemented it will
> + * take the updated gcontext into account.
> + */
> + if (CHARDEV_GET_CLASS(chr)->chr_update_read_handler) {
> + qemu_chr_set_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT);
> + }
> +
> }
>
> static int null_chr_write(Chardev *chr, const uint8_t *buf, int len)
- Re: [Qemu-devel] [PATCH v2 3/6] char: add a QEMU_CHAR_FEATURE_GCONTEXT flag,
Markus Armbruster <=