On Fri, Sep 26, 2014 at 08:05:29PM +0000, Mateusz Guzik wrote:
> Author: mjg
> Date: Fri Sep 26 20:05:28 2014
> New Revision: 272187
> URL: http://svnweb.freebsd.org/changeset/base/272187
>
> Log:
> MFC r270993:
>
> Fix up proc_realparent to always return correct process.
>
> Prior to the change it would always return initproc for non-traced
> processes.
>
> This fixes a regression in inferior().
>
> Approved by: re (marius)
>
Oops.. this is r270648. Still approvied by re (marius).
> Modified:
> stable/10/sys/kern/kern_descrip.c
> stable/10/sys/kern/vfs_vnops.c
> stable/10/sys/sys/file.h
> Directory Properties:
> stable/10/ (props changed)
>
> Modified: stable/10/sys/kern/kern_descrip.c
> ==============================================================================
> --- stable/10/sys/kern/kern_descrip.c Fri Sep 26 19:56:52 2014
> (r272186)
> +++ stable/10/sys/kern/kern_descrip.c Fri Sep 26 20:05:28 2014
> (r272187)
> @@ -477,7 +477,6 @@ kern_fcntl(struct thread *td, int fd, in
> struct vnode *vp;
> cap_rights_t rights;
> int error, flg, tmp;
> - u_int old, new;
> uint64_t bsize;
> off_t foffset;
>
> @@ -761,26 +760,24 @@ kern_fcntl(struct thread *td, int fd, in
> error = EBADF;
> break;
> }
> + vp = fp->f_vnode;
> + /*
> + * Exclusive lock synchronizes against f_seqcount reads and
> + * writes in sequential_heuristic().
> + */
> + error = vn_lock(vp, LK_EXCLUSIVE);
> + if (error != 0) {
> + fdrop(fp, td);
> + break;
> + }
> if (arg >= 0) {
> - vp = fp->f_vnode;
> - error = vn_lock(vp, LK_SHARED);
> - if (error != 0) {
> - fdrop(fp, td);
> - break;
> - }
> bsize = fp->f_vnode->v_mount->mnt_stat.f_iosize;
> - VOP_UNLOCK(vp, 0);
> fp->f_seqcount = (arg + bsize - 1) / bsize;
> - do {
> - new = old = fp->f_flag;
> - new |= FRDAHEAD;
> - } while (!atomic_cmpset_rel_int(&fp->f_flag, old, new));
> + atomic_set_int(&fp->f_flag, FRDAHEAD);
> } else {
> - do {
> - new = old = fp->f_flag;
> - new &= ~FRDAHEAD;
> - } while (!atomic_cmpset_rel_int(&fp->f_flag, old, new));
> + atomic_clear_int(&fp->f_flag, FRDAHEAD);
> }
> + VOP_UNLOCK(vp, 0);
> fdrop(fp, td);
> break;
>
>
> Modified: stable/10/sys/kern/vfs_vnops.c
> ==============================================================================
> --- stable/10/sys/kern/vfs_vnops.c Fri Sep 26 19:56:52 2014
> (r272186)
> +++ stable/10/sys/kern/vfs_vnops.c Fri Sep 26 20:05:28 2014
> (r272187)
> @@ -438,7 +438,8 @@ static int
> sequential_heuristic(struct uio *uio, struct file *fp)
> {
>
> - if (atomic_load_acq_int(&(fp->f_flag)) & FRDAHEAD)
> + ASSERT_VOP_LOCKED(fp->f_vnode, __func__);
> + if (fp->f_flag & FRDAHEAD)
> return (fp->f_seqcount << IO_SEQSHIFT);
>
> /*
>
> Modified: stable/10/sys/sys/file.h
> ==============================================================================
> --- stable/10/sys/sys/file.h Fri Sep 26 19:56:52 2014 (r272186)
> +++ stable/10/sys/sys/file.h Fri Sep 26 20:05:28 2014 (r272187)
> @@ -139,6 +139,7 @@ struct fileops {
> *
> * Below is the list of locks that protects members in struct file.
> *
> + * (a) f_vnode lock required (shared allows both reads and writes)
> * (f) protected with mtx_lock(mtx_pool_find(fp))
> * (d) cdevpriv_mtx
> * none not locked
> @@ -164,7 +165,7 @@ struct file {
> /*
> * DTYPE_VNODE specific fields.
> */
> - int f_seqcount; /* Count of sequential accesses. */
> + int f_seqcount; /* (a) Count of sequential accesses. */
> off_t f_nextoff; /* next expected read/write offset. */
> union {
> struct cdev_privdata *fvn_cdevpriv;
>
--
Mateusz Guzik <mjguzik gmail.com>
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