[PATCH] xen/console: pre-compute domain prefix for printouts

[dmkhn@xxxxxxxxx]

Every guest_printk() call computes "(d%d) " prefix on every call.
Move prefix generation to the domain creation time.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/arch/x86/pv/shim.c     | 2 ++
 xen/common/domain.c        | 2 ++
 xen/drivers/char/console.c | 6 +-----
 xen/include/xen/sched.h    | 1 +
 4 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/pv/shim.c b/xen/arch/x86/pv/shim.c
index 81e4a0516d..b9c034ccff 100644
--- a/xen/arch/x86/pv/shim.c
+++ b/xen/arch/x86/pv/shim.c
@@ -329,6 +329,8 @@ int pv_shim_shutdown(uint8_t reason)
 
     /* Update domain id. */
     d->domain_id = get_initial_domain_id();
+    snprintf(d->domain_prefix, sizeof(d->domain_prefix),
+             "(d%d) ", d->domain_id);
 
     /* Clean the iomem range. */
     BUG_ON(iomem_deny_access(d, 0, ~0UL));
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 0c4cc77111..49d4cb8221 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -681,6 +681,8 @@ struct domain *domain_create(domid_t domid,
 
     /* Sort out our idea of is_system_domain(). */
     d->domain_id = domid;
+    snprintf(d->domain_prefix, sizeof(d->domain_prefix),
+             "(d%d) ", d->domain_id);
     d->unique_id = get_unique_id();
 
     /* Holding CDF_* internal flags. */
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 235d55bbff..2e23910dfa 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -965,12 +965,8 @@ void printk(const char *fmt, ...)
 void guest_printk(const struct domain *d, const char *fmt, ...)
 {
     va_list args;
-    char prefix[16];
-
-    snprintf(prefix, sizeof(prefix), "(d%d) ", d->domain_id);
-
     va_start(args, fmt);
-    vprintk_common(prefix, fmt, args);
+    vprintk_common(d->domain_prefix, fmt, args);
     va_end(args);
 }
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 037c83fda2..e90921dbd1 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -368,6 +368,7 @@ struct evtchn_port_ops;
 struct domain
 {
     domid_t          domain_id;
+    char             domain_prefix[16]; /* '(dX) ' prefix for printouts */
 
     unsigned int     max_vcpus;
 
-- 
2.34.1