svn commit: r184641 - in stable/7/sys: . kern

[Scott Long]

In stable branches, and especially during release cycles, would it be 
possible to annotate whether changes like this fix known panics or 
user-visible bugs?

Scott


Konstantin Belousov wrote:
> Author: kib
> Date: Tue Nov  4 15:56:44 2008
> New Revision: 184641
> URL: http://svn.freebsd.org/changeset/base/184641
> 
> Log:
>   MFC r184409:
>   Protect check for v_pollinfo == NULL and assignment of the newly allocated
>   vpollinfo with vnode interlock. Fully initialize vpollinfo before putting
>   pointer to it into vp->v_pollinfo.
>   
>   Approved by:	re (kensmith)
> 
> Modified:
>   stable/7/sys/   (props changed)
>   stable/7/sys/kern/vfs_subr.c
> 
> Modified: stable/7/sys/kern/vfs_subr.c
> ==============================================================================
> --- stable/7/sys/kern/vfs_subr.c	Tue Nov  4 15:47:06 2008	(r184640)
> +++ stable/7/sys/kern/vfs_subr.c	Tue Nov  4 15:56:44 2008	(r184641)
> @@ -109,7 +109,7 @@ static void	vgonel(struct vnode *);
>  static void	vfs_knllock(void *arg);
>  static void	vfs_knlunlock(void *arg);
>  static int	vfs_knllocked(void *arg);
> -
> +static void	destroy_vpollinfo(struct vpollinfo *vi);
>  
>  /*
>   * Enable Giant pushdown based on whether or not the vm is mpsafe in this
> @@ -815,11 +815,8 @@ vdestroy(struct vnode *vp)
>  #ifdef MAC
>  	mac_destroy_vnode(vp);
>  #endif
> -	if (vp->v_pollinfo != NULL) {
> -		knlist_destroy(&vp->v_pollinfo->vpi_selinfo.si_note);
> -		mtx_destroy(&vp->v_pollinfo->vpi_lock);
> -		uma_zfree(vnodepoll_zone, vp->v_pollinfo);
> -	}
> +	if (vp->v_pollinfo != NULL)
> +		destroy_vpollinfo(vp->v_pollinfo);
>  #ifdef INVARIANTS
>  	/* XXX Elsewhere we can detect an already freed vnode via NULL v_op. */
>  	vp->v_op = NULL;
> @@ -3050,6 +3047,14 @@ vbusy(struct vnode *vp)
>  	mtx_unlock(&vnode_free_list_mtx);
>  }
>  
> +static void
> +destroy_vpollinfo(struct vpollinfo *vi)
> +{
> +	knlist_destroy(&vi->vpi_selinfo.si_note);
> +	mtx_destroy(&vi->vpi_lock);
> +	uma_zfree(vnodepoll_zone, vi);
> +}
> +
>  /*
>   * Initalize per-vnode helper structure to hold poll-related state.
>   */
> @@ -3058,15 +3063,20 @@ v_addpollinfo(struct vnode *vp)
>  {
>  	struct vpollinfo *vi;
>  
> +	if (vp->v_pollinfo != NULL)
> +		return;
>  	vi = uma_zalloc(vnodepoll_zone, M_WAITOK);
> +	mtx_init(&vi->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
> +	knlist_init(&vi->vpi_selinfo.si_note, vp, vfs_knllock,
> +	    vfs_knlunlock, vfs_knllocked);
> +	VI_LOCK(vp);
>  	if (vp->v_pollinfo != NULL) {
> -		uma_zfree(vnodepoll_zone, vi);
> +		VI_UNLOCK(vp);
> +		destroy_vpollinfo(vi);
>  		return;
>  	}
>  	vp->v_pollinfo = vi;
> -	mtx_init(&vp->v_pollinfo->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
> -	knlist_init(&vp->v_pollinfo->vpi_selinfo.si_note, vp, vfs_knllock,
> -	    vfs_knlunlock, vfs_knllocked);
> +	VI_UNLOCK(vp);
>  }
>  
>  /*
> @@ -3081,8 +3091,7 @@ int
>  vn_pollrecord(struct vnode *vp, struct thread *td, int events)
>  {
>  
> -	if (vp->v_pollinfo == NULL)
> -		v_addpollinfo(vp);
> +	v_addpollinfo(vp);
>  	mtx_lock(&vp->v_pollinfo->vpi_lock);
>  	if (vp->v_pollinfo->vpi_revents & events) {
>  		/*
> @@ -3917,8 +3926,7 @@ vfs_kqfilter(struct vop_kqfilter_args *a
>  
>  	kn->kn_hook = (caddr_t)vp;
>  
> -	if (vp->v_pollinfo == NULL)
> -		v_addpollinfo(vp);
> +	v_addpollinfo(vp);
>  	if (vp->v_pollinfo == NULL)
>  		return (ENOMEM);
>  	knl = &vp->v_pollinfo->vpi_selinfo.si_note;