On Sun, 4 Mar 2007, Divacky Roman wrote:
I noticed that kern___getcwd() calls vn_fullpath1() with Giant held like
this:
mtx_lock(&Giant);
FILEDESC_LOCK(fdp);
error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf,
&bp, buflen);
FILEDESC_UNLOCK(fdp);
mtx_unlock(&Giant);
on the other hand vn_fullpath() calls it without Giant held like this:
FILEDESC_LOCK(fdp);
error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN);
FILEDESC_UNLOCK(fdp);
I dont see much difference in the callings so I wonder if holding Giant is
necessary when calling vn_fullpath1(). Because we either - do one unecessary
locking operation or unsufficiently lock it.
thnx for explaining to me and possibly fixing it.
I suspect that the Giant acquisition there is a conservative acquisition based
on VFS not having been MPSAFE, and can be removed.
Robert N M Watson
Computer Laboratory
University of Cambridge
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