> On 16 Jun 2021, at 15:43, Julien Grall <jul...@xen.org> wrote:
>
> From: Julien Grall <jgr...@amazon.com>
>
> Currently, the callbacks can_read and can_write are called directly. This
> doesn't allow us to add generic check and therefore requires duplication.
>
> At the moment, one check that could benefit to be common is whether the
> connection should ignored. The position is slightly different between
> domain and socket because for the latter we want to check the state of
> the file descriptor first.
>
> In follow-up patches, there will be more potential generic checks.
>
> This patch provides wrappers to read/write a connection and move
> the check ->is_ignored after the callback for everyone.
>
> This also requires to replace the direct call to domain_can_read()
> and domain_can_write() with the new wrapper. At the same time,
> both functions can now be static. Note that the implementations need
> to be moved earlier in the file xenstored_domain.c to avoid
> declaring the prototype.
>
> Signed-off-by: Julien Grall <jgr...@amazon.com>
Reviewed-by: Luca Fancellu <luca.fance...@arm.com>
> ---
> tools/xenstore/xenstored_core.c | 18 ++++++++++----
> tools/xenstore/xenstored_domain.c | 40 +++++++++++++------------------
> tools/xenstore/xenstored_domain.h | 4 ----
> 3 files changed, 31 insertions(+), 31 deletions(-)
>
> diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
> index 51d210828922..2e5760fe4599 100644
> --- a/tools/xenstore/xenstored_core.c
> +++ b/tools/xenstore/xenstored_core.c
> @@ -334,6 +334,16 @@ static int destroy_conn(void *_conn)
> return 0;
> }
>
> +static bool conn_can_read(struct connection *conn)
> +{
> + return conn->funcs->can_read(conn) && !conn->is_ignored;
> +}
> +
> +static bool conn_can_write(struct connection *conn)
> +{
> + return conn->funcs->can_write(conn) && !conn->is_ignored;
> +}
> +
> /* This function returns index inside the array if succeed, -1 if fail */
> static int set_fd(int fd, short events)
> {
> @@ -396,8 +406,8 @@ static void initialize_fds(int *p_sock_pollfd_idx, int
> *ptimeout)
> list_for_each_entry(conn, &connections, list) {
> if (conn->domain) {
> wrl_check_timeout(conn->domain, now, ptimeout);
> - if (domain_can_read(conn) ||
> - (domain_can_write(conn) &&
> + if (conn_can_read(conn) ||
> + (conn_can_write(conn) &&
> !list_empty(&conn->out_list)))
> *ptimeout = 0;
> } else {
> @@ -2325,14 +2335,14 @@ int main(int argc, char *argv[])
> if (&next->list != &connections)
> talloc_increase_ref_count(next);
>
> - if (conn->funcs->can_read(conn))
> + if (conn_can_read(conn))
> handle_input(conn);
> if (talloc_free(conn) == 0)
> continue;
>
> talloc_increase_ref_count(conn);
>
> - if (conn->funcs->can_write(conn))
> + if (conn_can_write(conn))
> handle_output(conn);
> if (talloc_free(conn) == 0)
> continue;
> diff --git a/tools/xenstore/xenstored_domain.c
> b/tools/xenstore/xenstored_domain.c
> index 6d8d29cbe41c..47e9107c144e 100644
> --- a/tools/xenstore/xenstored_domain.c
> +++ b/tools/xenstore/xenstored_domain.c
> @@ -172,6 +172,23 @@ static int readchn(struct connection *conn, void *data,
> unsigned int len)
> return len;
> }
>
> +static bool domain_can_write(struct connection *conn)
> +{
> + struct xenstore_domain_interface *intf = conn->domain->interface;
> +
> + return ((intf->rsp_prod - intf->rsp_cons) != XENSTORE_RING_SIZE);
> +}
> +
> +static bool domain_can_read(struct connection *conn)
> +{
> + struct xenstore_domain_interface *intf = conn->domain->interface;
> +
> + if (domain_is_unprivileged(conn) && conn->domain->wrl_credit < 0)
> + return false;
> +
> + return (intf->req_cons != intf->req_prod);
> +}
> +
> static const struct interface_funcs domain_funcs = {
> .write = writechn,
> .read = readchn,
> @@ -290,19 +307,6 @@ void handle_event(void)
> barf_perror("Failed to write to event fd");
> }
>
> -bool domain_can_read(struct connection *conn)
> -{
> - struct xenstore_domain_interface *intf = conn->domain->interface;
> -
> - if (domain_is_unprivileged(conn) && conn->domain->wrl_credit < 0)
> - return false;
> -
> - if (conn->is_ignored)
> - return false;
> -
> - return (intf->req_cons != intf->req_prod);
> -}
> -
> static bool domid_is_unprivileged(unsigned int domid)
> {
> return domid != 0 && domid != priv_domid;
> @@ -314,16 +318,6 @@ bool domain_is_unprivileged(struct connection *conn)
> domid_is_unprivileged(conn->domain->domid);
> }
>
> -bool domain_can_write(struct connection *conn)
> -{
> - struct xenstore_domain_interface *intf = conn->domain->interface;
> -
> - if (conn->is_ignored)
> - return false;
> -
> - return ((intf->rsp_prod - intf->rsp_cons) != XENSTORE_RING_SIZE);
> -}
> -
> static char *talloc_domain_path(void *context, unsigned int domid)
> {
> return talloc_asprintf(context, "/local/domain/%u", domid);
> diff --git a/tools/xenstore/xenstored_domain.h
> b/tools/xenstore/xenstored_domain.h
> index 62ee471ea6aa..1e929b8f8c6f 100644
> --- a/tools/xenstore/xenstored_domain.h
> +++ b/tools/xenstore/xenstored_domain.h
> @@ -51,10 +51,6 @@ void domain_deinit(void);
> /* Returns the implicit path of a connection (only domains have this) */
> const char *get_implicit_path(const struct connection *conn);
>
> -/* Can connection attached to domain read/write. */
> -bool domain_can_read(struct connection *conn);
> -bool domain_can_write(struct connection *conn);
> -
> bool domain_is_unprivileged(struct connection *conn);
>
> /* Remove node permissions for no longer existing domains. */
> --
> 2.17.1
>
>
