sanchayanmaity/xv6-cs450
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slight rearrangement; sleep on b not buf.

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rsc 2009-05-31 00:23:00 +00:00
parent d827c8f3c8
commit 0ca9ca0c55
1 changed files with 8 additions and 8 deletions
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12
bio.c
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@ -69,22 +69,22 @@ bget(uint dev, uint sector)
for(b = bufhead.next; b != &bufhead; b = b->next){ for(b = bufhead.next; b != &bufhead; b = b->next){
if((b->flags & (B_BUSY|B_VALID)) && if((b->flags & (B_BUSY|B_VALID)) &&
b->dev == dev && b->sector == sector){ b->dev == dev && b->sector == sector){
if(b->flags & B_BUSY){ if(!(b->flags & B_BUSY)){
sleep(buf, &buf_table_lock);
goto loop;
}
b->flags |= B_BUSY; b->flags |= B_BUSY;
release(&buf_table_lock); release(&buf_table_lock);
return b; return b;
} }
sleep(b, &buf_table_lock);
goto loop;
}
} }
// Allocate fresh block. // Allocate fresh block.
for(b = bufhead.prev; b != &bufhead; b = b->prev){ for(b = bufhead.prev; b != &bufhead; b = b->prev){
if((b->flags & B_BUSY) == 0){ if((b->flags & B_BUSY) == 0){
b->flags = B_BUSY;
b->dev = dev; b->dev = dev;
b->sector = sector; b->sector = sector;
b->flags = B_BUSY;
release(&buf_table_lock); release(&buf_table_lock);
return b; return b;
} }
@ -131,7 +131,7 @@ brelse(struct buf *b)
bufhead.next = b; bufhead.next = b;
b->flags &= ~B_BUSY; b->flags &= ~B_BUSY;
wakeup(buf); wakeup(b);
release(&buf_table_lock); release(&buf_table_lock);
} }