sanchayanmaity/xv6-cs450
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i cannot prove that release before wakeup is wrong, but i cannot convince myself it is right either

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rsc 2007-08-14 19:10:57 +00:00
parent 4bc5056c19
commit ea6e370964
1 changed files with 2 additions and 8 deletions
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10
pipe.c
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@ -64,7 +64,6 @@ void
pipe_close(struct pipe *p, int writable) pipe_close(struct pipe *p, int writable)
{ {
acquire(&p->lock); acquire(&p->lock);
if(writable){ if(writable){
p->writeopen = 0; p->writeopen = 0;
wakeup(&p->readp); wakeup(&p->readp);
@ -72,7 +71,6 @@ pipe_close(struct pipe *p, int writable)
p->readopen = 0; p->readopen = 0;
wakeup(&p->writep); wakeup(&p->writep);
} }
release(&p->lock); release(&p->lock);
if(p->readopen == 0 && p->writeopen == 0) if(p->readopen == 0 && p->writeopen == 0)
@ -86,7 +84,6 @@ pipe_write(struct pipe *p, char *addr, int n)
int i; int i;
acquire(&p->lock); acquire(&p->lock);
for(i = 0; i < n; i++){ for(i = 0; i < n; i++){
while(((p->writep + 1) % PIPESIZE) == p->readp){ while(((p->writep + 1) % PIPESIZE) == p->readp){
if(p->readopen == 0 || cp->killed){ if(p->readopen == 0 || cp->killed){
@ -99,9 +96,8 @@ pipe_write(struct pipe *p, char *addr, int n)
p->data[p->writep] = addr[i]; p->data[p->writep] = addr[i];
p->writep = (p->writep + 1) % PIPESIZE; p->writep = (p->writep + 1) % PIPESIZE;
} }
release(&p->lock);
wakeup(&p->readp); wakeup(&p->readp);
release(&p->lock);
return i; return i;
} }
@ -111,7 +107,6 @@ pipe_read(struct pipe *p, char *addr, int n)
int i; int i;
acquire(&p->lock); acquire(&p->lock);
while(p->readp == p->writep){ while(p->readp == p->writep){
if(p->writeopen == 0 || cp->killed){ if(p->writeopen == 0 || cp->killed){
release(&p->lock); release(&p->lock);
@ -125,8 +120,7 @@ pipe_read(struct pipe *p, char *addr, int n)
addr[i] = p->data[p->readp]; addr[i] = p->data[p->readp];
p->readp = (p->readp + 1) % PIPESIZE; p->readp = (p->readp + 1) % PIPESIZE;
} }
release(&p->lock);
wakeup(&p->writep); wakeup(&p->writep);
release(&p->lock);
return i; return i;
} }