cvs add spinlock.h

fix race in schedule()

1 files changed, 2 insertions, 1 deletions

diff --git a/proc.c b/proc.c
index 07a88d8..4c2586d 100644
--- a/proc.c
+++ b/proc.c
@@ -148,7 +148,6 @@ scheduler(void)
 
     if(i < NPROC){
       np->state = RUNNING;
-      release(&proc_table_lock);
       break;
     }
     
@@ -159,6 +158,8 @@ scheduler(void)
   cpus[cpu()].lastproc = np;
   curproc[cpu()] = np;
   
+  release(&proc_table_lock);
+
   // h/w sets busy bit in TSS descriptor sometimes, and faults
   // if it's set in LTR. so clear tss descriptor busy bit.
   np->gdt[SEG_TSS].sd_type = STS_T32A;