[PATCH v4 09/10] evtchn: type adjustments

[Jan Beulich <jbeulich@xxxxxxxx>]

First of all avoid "long" when "int" suffices, i.e. in particular when
merely conveying error codes. 32-bit values are slightly cheaper to
deal with on x86, and their processing is at least no more expensive on
Arm. Where possible use evtchn_port_t for port numbers and unsigned int
for other unsigned quantities in adjacent code. In evtchn_set_priority()
eliminate a local variable altogether instead of changing its type.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v4: New.

--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -287,13 +287,12 @@ void evtchn_free(struct domain *d, struc
     xsm_evtchn_close_post(chn);
 }
 
-static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
+static int evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc)
 {
     struct evtchn *chn;
     struct domain *d;
-    int            port;
+    int            port, rc;
     domid_t        dom = alloc->dom;
-    long           rc;
 
     d = rcu_lock_domain_by_any_id(dom);
     if ( d == NULL )
@@ -346,13 +345,13 @@ static void double_evtchn_unlock(struct
     evtchn_write_unlock(rchn);
 }
 
-static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
+static int evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
 {
     struct evtchn *lchn, *rchn;
     struct domain *ld = current->domain, *rd;
-    int            lport, rport = bind->remote_port;
+    int            lport, rc;
+    evtchn_port_t  rport = bind->remote_port;
     domid_t        rdom = bind->remote_dom;
-    long           rc;
 
     if ( rdom == DOMID_SELF )
         rdom = current->domain->domain_id;
@@ -482,12 +481,12 @@ int evtchn_bind_virq(evtchn_bind_virq_t
 }
 
 
-static long evtchn_bind_ipi(evtchn_bind_ipi_t *bind)
+static int evtchn_bind_ipi(evtchn_bind_ipi_t *bind)
 {
     struct evtchn *chn;
     struct domain *d = current->domain;
-    int            port, vcpu = bind->vcpu;
-    long           rc = 0;
+    int            port, rc = 0;
+    unsigned int   vcpu = bind->vcpu;
 
     if ( domain_vcpu(d, vcpu) == NULL )
         return -ENOENT;
@@ -541,16 +540,16 @@ static void unlink_pirq_port(struct evtc
 }
 
 
-static long evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
+static int evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
 {
     struct evtchn *chn;
     struct domain *d = current->domain;
     struct vcpu   *v = d->vcpu[0];
     struct pirq   *info;
-    int            port = 0, pirq = bind->pirq;
-    long           rc;
+    int            port = 0, rc;
+    unsigned int   pirq = bind->pirq;
 
-    if ( (pirq < 0) || (pirq >= d->nr_pirqs) )
+    if ( pirq >= d->nr_pirqs )
         return -EINVAL;
 
     if ( !is_hvm_domain(d) && !pirq_access_permitted(d, pirq) )
@@ -606,7 +605,7 @@ int evtchn_close(struct domain *d1, int
 {
     struct domain *d2 = NULL;
     struct evtchn *chn1 = _evtchn_from_port(d1, port1), *chn2 = NULL;
-    long           rc = 0;
+    int            rc = 0;
 
     if ( !chn1 )
         return -EINVAL;
@@ -1011,7 +1010,7 @@ int evtchn_status(evtchn_status_t *statu
     struct domain   *d;
     domid_t          dom = status->dom;
     struct evtchn   *chn;
-    long             rc = 0;
+    int              rc = 0;
 
     d = rcu_lock_domain_by_any_id(dom);
     if ( d == NULL )
@@ -1077,11 +1076,11 @@ int evtchn_status(evtchn_status_t *statu
 }
 
 
-long evtchn_bind_vcpu(unsigned int port, unsigned int vcpu_id)
+int evtchn_bind_vcpu(evtchn_port_t port, unsigned int vcpu_id)
 {
     struct domain *d = current->domain;
     struct evtchn *chn;
-    long           rc = 0;
+    int           rc = 0;
     struct vcpu   *v;
 
     /* Use the vcpu info to prevent speculative out-of-bound accesses */
@@ -1220,12 +1219,11 @@ int evtchn_reset(struct domain *d, bool
     return rc;
 }
 
-static long evtchn_set_priority(const struct evtchn_set_priority *set_priority)
+static int evtchn_set_priority(const struct evtchn_set_priority *set_priority)
 {
     struct domain *d = current->domain;
-    unsigned int port = set_priority->port;
-    struct evtchn *chn = _evtchn_from_port(d, port);
-    long ret;
+    struct evtchn *chn = _evtchn_from_port(d, set_priority->port);
+    int ret;
 
     if ( !chn )
         return -EINVAL;
@@ -1241,7 +1239,7 @@ static long evtchn_set_priority(const st
 
 long do_event_channel_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
-    long rc;
+    int rc;
 
     switch ( cmd )
     {
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -54,7 +54,7 @@ void send_guest_pirq(struct domain *, co
 int evtchn_send(struct domain *d, unsigned int lport);
 
 /* Bind a local event-channel port to the specified VCPU. */
-long evtchn_bind_vcpu(unsigned int port, unsigned int vcpu_id);
+int evtchn_bind_vcpu(evtchn_port_t port, unsigned int vcpu_id);
 
 /* Bind a VIRQ. */
 int evtchn_bind_virq(evtchn_bind_virq_t *bind, evtchn_port_t port);