Imbus/xv6-riscv-kernel
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avoid deadlock by calling begin_trans() before locking any inodes

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This commit is contained in:
Robert Morris 2011-08-15 12:44:20 -04:00
parent c95ce31c59
commit 5053dd6a6d
5 changed files with 66 additions and 15 deletions
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14
sysfile.c
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@ -116,14 +116,16 @@ sys_link(void)
return -1;
if((ip = namei(old)) == 0)
return -1;
begin_trans();
ilock(ip);
if(ip->type == T_DIR){
iunlockput(ip);
commit_trans();
return -1;
}
begin_trans();
ip->nlink++;
iupdate(ip);
iunlock(ip);
@ -180,16 +182,21 @@ sys_unlink(void)
return -1;
if((dp = nameiparent(path, name)) == 0)
return -1;
begin_trans();
ilock(dp);
// Cannot unlink "." or "..".
if(namecmp(name, ".") == 0 || namecmp(name, "..") == 0){
iunlockput(dp);
commit_trans();
return -1;
}
if((ip = dirlookup(dp, name, &off)) == 0){
iunlockput(dp);
commit_trans();
return -1;
}
ilock(ip);
@ -199,11 +206,10 @@ sys_unlink(void)
if(ip->type == T_DIR && !isdirempty(ip)){
iunlockput(ip);
iunlockput(dp);
commit_trans();
return -1;
}
begin_trans();
memset(&de, 0, sizeof(de));
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("unlink: writei");