bitkeeper revision 1.28 (3e4bdf33sufyB9J_a-mb8comwfYdfw)

more elegant way of reading multiple values atomically

diff --git a/xenolinux-2.4.16-sparse/arch/xeno/kernel/time.c b/xenolinux-2.4.16-sparse/arch/xeno/kernel/time.c
index 7ba39d22cac18279d0ac10de9e016830d26ce00a..4999af6642adcaf571cf7018d0ea4f9c42ffe7cb 100644 (file)
--- a/xenolinux-2.4.16-sparse/arch/xeno/kernel/time.c
+++ b/xenolinux-2.4.16-sparse/arch/xeno/kernel/time.c
@@ -101,16 +101,12 @@ static inline long long get_s_time(void)
 
        spin_lock_irqsave(&hyp_stime_lock, flags);
 
-    pcc = HYPERVISOR_shared_info->st_timestamp;
-       mb();   
-       if (pcc != shadow_st_pcc) {
-st_again:
-               shadow_st_pcc = HYPERVISOR_shared_info->st_timestamp;
+       while ((pcc = HYPERVISOR_shared_info->st_timestamp) != shadow_st_pcc)
+       {
+               barrier();
+               shadow_st_pcc = pcc;
                shadow_st     = HYPERVISOR_shared_info->system_time;
-               pcc = HYPERVISOR_shared_info->st_timestamp;
-               mb();
-               if (pcc != shadow_st_pcc)
-                       goto st_again;
+               barrier();
        }
 
     now = shadow_st;
@@ -120,7 +116,9 @@ st_again:
        delta = ((u64)delta_tsc * st_scale_f);
        delta >>= 32;
        delta += ((u64)delta_tsc * st_scale_i);
+
        spin_unlock_irqrestore(&hyp_time_lock, flags);
+
     return now + delta; 
 
 }
@@ -145,19 +143,14 @@ void do_gettimeofday(struct timeval *tv)
 
        spin_lock_irqsave(&hyp_wctime_lock, flags);
 
-       version = HYPERVISOR_shared_info->wc_version;
-       mb();
-       if (version != shadow_wc_version) {
-       wc_again:
-               shadow_wc_version   = HYPERVISOR_shared_info->wc_version;
+       while ((version = HYPERVISOR_shared_info->wc_version)!= shadow_wc_version)
+       {
+               barrier();
+               shadow_wc_version   = version;
                shadow_tv_sec       = HYPERVISOR_shared_info->tv_sec;
                shadow_tv_usec      = HYPERVISOR_shared_info->tv_usec;
                shadow_wc_timestamp = HYPERVISOR_shared_info->wc_timestamp;
-               shadow_wc_version   = HYPERVISOR_shared_info->wc_version;
-               version =  HYPERVISOR_shared_info->wc_version;
-               mb();
-               if (version != shadow_wc_version)
-                       goto wc_again;
+               barrier();
        }
 
        now   = NOW();