[v6,3/3] evtchn: type adjustments

Commit Message

Jan Beulich May 27, 2021, 11:28 a.m. UTC

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 <[e-mail]>
---
v6: Re-base for re-ordering / shrinking of series.
v4: New.

Comments

Roger Pau Monne May 27, 2021, 1:52 p.m. UTC | #1

On Thu, May 27, 2021 at 01:28:59PM +0200, Jan Beulich wrote:
> 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 <[e-mail]>

Acked-by: Roger Pau Monné <[e-mail]>

Just one style nit below.

> -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;
                     ^ I think you are missing one space here, other
                       functions in the same file don't align at the *.

Thanks, Roger.

Patch

--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -284,13 +284,12 @@  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 )
@@ -342,13 +341,13 @@  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 ( (rd = rcu_lock_domain_by_any_id(rdom)) == NULL )
         return -ESRCH;
@@ -484,12 +483,12 @@  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;
@@ -543,16 +542,16 @@  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) )
@@ -608,7 +607,7 @@  int evtchn_close(struct domain *d1, int
 {
     struct domain *d2 = NULL;
     struct evtchn *chn1 = _evtchn_from_port(d1, port1), *chn2;
-    long           rc = 0;
+    int            rc = 0;
 
     if ( !chn1 )
         return -EINVAL;
@@ -959,7 +958,7 @@  int evtchn_status(evtchn_status_t *statu
     domid_t          dom = status->dom;
     int              port = status->port;
     struct evtchn   *chn;
-    long             rc = 0;
+    int              rc = 0;
 
     d = rcu_lock_domain_by_any_id(dom);
     if ( d == NULL )
@@ -1025,11 +1024,11 @@  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 */
@@ -1168,12 +1167,11 @@  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;
@@ -1189,7 +1187,7 @@  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);