Am 10.08.2012 04:10, schrieb Corey Bryant:
> This patch adds support that enables passing of file descriptors
> to the QEMU monitor where they will be stored in specified file
> descriptor sets.
>
> A file descriptor set can be used by a client like libvirt to
> store file descriptors for the same file. This allows the
> client to open a file with different access modes (O_RDWR,
> O_WRONLY, O_RDONLY) and add/remove the passed fds to/from an fd
> set as needed. This will allow QEMU to (in a later patch in this
> series) "open" and "reopen" the same file by dup()ing the fd in
> the fd set that corresponds to the file, where the fd has the
> matching access mode flag that QEMU requests.
>
> The new QMP commands are:
> add-fd: Add a file descriptor to an fd set
> remove-fd: Remove a file descriptor from an fd set
> query-fdsets: Return information describing all fd sets
>
> Note: These commands are not compatible with the existing getfd
> and closefd QMP commands.
>
> Signed-off-by: Corey Bryant <coreyb@xxxxxxxxxxxxxxxxxx>
> ---
> v5:
> -This patch is new in v5 and replaces the pass-fd QMP command
> from v4.
> -By grouping fds in fd sets, we ease managability with an fd
> set per file, addressing concerns raised in v4 about handling
> "reopens" and preventing fd leakage. (eblake@xxxxxxxxxx,
> kwolf@xxxxxxxxxx, dberrange@xxxxxxxxxx)
>
> v6
> -Make @fd optional for remove-fd (eblake@xxxxxxxxxx)
> -Make @fdset-id optional for add-fd (eblake@xxxxxxxxxx)
>
> v7:
> -Share fd sets among all monitor connections (kwolf@xxxxxxxxxx)
> -Added mon_refcount to keep track of monitor connection count.
>
> v8:
> -Add opaque string to add-fd/query-fdsets.
> (stefanha@xxxxxxxxxxxxxxxxxx)
> -Use camel case for structures. (stefanha@xxxxxxxxxxxxxxxxxx)
> -Don't return in-use and refcount from query-fdsets.
> (stefanha@xxxxxxxxxxxxxxxxxx)
> -Don't return removed fd's from query-fdsets.
> (stefanha@xxxxxxxxxxxxxxxxxx)
> -Use fdset-id rather than fdset_id. (eblake@xxxxxxxxxx)
> -Fix fd leak in qmp_add_fd(). (stefanha@xxxxxxxxxxxxxxxxxx)
> -Update QMP errors. (stefanha@xxxxxxxxxxxxxxxxxx, eblake@xxxxxxxxxx)
>
> monitor.c | 188 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> qapi-schema.json | 98 ++++++++++++++++++++++++++++
> qmp-commands.hx | 117 +++++++++++++++++++++++++++++++++
> 3 files changed, 403 insertions(+)
>
> diff --git a/monitor.c b/monitor.c
> index 49dccfe..f9a0577 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -140,6 +140,24 @@ struct mon_fd_t {
> QLIST_ENTRY(mon_fd_t) next;
> };
>
> +/* file descriptor associated with a file descriptor set */
> +typedef struct MonFdsetFd MonFdsetFd;
> +struct MonFdsetFd {
> + int fd;
> + bool removed;
> + char *opaque;
> + QLIST_ENTRY(MonFdsetFd) next;
> +};
> +
> +/* file descriptor set containing fds passed via SCM_RIGHTS */
> +typedef struct MonFdset MonFdset;
> +struct MonFdset {
> + int64_t id;
> + int refcount;
> + QLIST_HEAD(, MonFdsetFd) fds;
> + QLIST_ENTRY(MonFdset) next;
> +};
> +
> typedef struct MonitorControl {
> QObject *id;
> JSONMessageParser parser;
> @@ -211,6 +229,8 @@ static inline int mon_print_count_get(const Monitor *mon) { return 0; }
> #define QMP_ACCEPT_UNKNOWNS 1
>
> static QLIST_HEAD(mon_list, Monitor) mon_list;
> +static QLIST_HEAD(mon_fdsets, MonFdset) mon_fdsets;
> +static int mon_refcount;
You introduce mon_refcount in this patch and check it against 0 in one
place, but it never gets changed until patch 3 is applied. Would it make
sense to do both in the same patch?
Kevin
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