-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I think I may have found a bug in vget(). Here is the code from vfs_subr.c:1.1.1.6 int vget(vp, flags, p) struct vnode *vp; int flags; struct proc *p; { int error = 0; retry: /* * If the vnode is in the process of being cleaned out for * another use, we wait for the cleaning to finish and then * return failure. Cleaning is determined by checking that * the VXLOCK flag is set. */ if ((flags & LK_INTERLOCK) == 0) simple_lock(&vp->v_interlock); if ((vp->v_flag & VXLOCK) || (vp->v_flag & VORECLAIM)) { vp->v_flag |= VXWANT; simple_unlock(&vp->v_interlock); (void)tsleep((caddr_t)vp, PINOD, "vget", 0); return (ENOENT); } /* * vnode is being terminated. * wait for vnode_pager_no_senders() to clear VTERMINATE */ if (ISSET(vp->v_flag, VTERMINATE)) { SET(vp->v_flag, VTERMWANT); simple_unlock(&vp->v_interlock); (void)tsleep((caddr_t)&vp->v_ubcinfo, PINOD, "vclean", 0); return (ENOENT); } /* * if the vnode is being initialized, * wait for it to finish initialization */ if (ISSET(vp->v_flag, VUINIT)) { if (ISSET(vp->v_flag, VUINIT)) { SET(vp->v_flag, VUWANT); simple_unlock(&vp->v_interlock); (void) tsleep((caddr_t)vp, PINOD, "vget2", 0); goto retry; } } ... In the last case [ if (ISSET(vp->v_flag, VUINIT)) ], where the thread sleeps waiting for the VNODE to finish init, the interlock is dropped before waiting, but after returning from the wait it jumps immediately to retry: w/o checking flags for LK_INTERLOCK. If LK_INTERLOCK is set, then the interlock won't be acquired at the beginning of retry:. Maybe I'm missing something, but before going to retry, shouldn't LK_INTERLOCK be cleared or if set then then re-acquire the lock before the jump? Something like this: /* * if the vnode is being initialized, * wait for it to finish initialization */ if (ISSET(vp->v_flag, VUINIT)) { if (ISSET(vp->v_flag, VUINIT)) { SET(vp->v_flag, VUWANT); simple_unlock(&vp->v_interlock); (void) tsleep((caddr_t)vp, PINOD, "vget2", 0); flags &= ~LK_INTERLOCK; goto retry; } } Brian Bergstrand <http://www.classicalguitar.net/brian/> PGP Key ID: 0xB6C7B6A2 We are not retreating - we are advancing in another direction. - General Douglas MacArthur -----BEGIN PGP SIGNATURE----- Version: PGP 8.0 iQA/AwUBPmrdjHnR2Fu2x7aiEQK3DwCg4ysw54MxU0zrNpWMn7lQy8a2EmQAn3qO dBTnYTyYAMdbpmiHNKY+t8Ao =Qm9E -----END PGP SIGNATURE----- _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.