On Tue, Apr 03, 2018 at 04:43:17PM +0200, Martin Pieuchot wrote:
> Here's another refactoring to properly reference count a 'struct file *'
> just after calling fd_getfile().
>
> Instead of incrementing `f_count' by hand, give the current reference
> to finishdup() like it is done in other places in the same file.
>
> Ok?
OK bluhm@
> Index: kern/kern_descrip.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_descrip.c,v
> retrieving revision 1.144
> diff -u -p -r1.144 kern_descrip.c
> --- kern/kern_descrip.c 3 Apr 2018 09:00:03 -0000 1.144
> +++ kern/kern_descrip.c 3 Apr 2018 13:30:47 -0000
> @@ -1274,6 +1274,8 @@ dupfdopen(struct proc *p, int indx, int
> struct filedesc *fdp = p->p_fd;
> int dupfd = p->p_dupfd;
> struct file *wfp;
> + int error, flags;
> + register_t dummy;
>
> fdpassertlocked(fdp);
>
> @@ -1297,24 +1299,26 @@ dupfdopen(struct proc *p, int indx, int
> */
> if ((wfp = fd_getfile(fdp, dupfd)) == NULL)
> return (EBADF);
> + FREF(wfp);
>
> /*
> * Check that the mode the file is being opened for is a
> * subset of the mode of the existing descriptor.
> */
> - if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
> + if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag) {
> + FRELE(wfp, p);
> return (EACCES);
> - if (wfp->f_count == LONG_MAX-2)
> - return (EDEADLK);
> + }
>
> - fdp->fd_ofiles[indx] = wfp;
> - fdp->fd_ofileflags[indx] = (fdp->fd_ofileflags[indx] & UF_EXCLOSE) |
> - (fdp->fd_ofileflags[dupfd] & ~UF_EXCLOSE);
> + flags = fdp->fd_ofileflags[indx] & UF_EXCLOSE;
> if (ISSET(p->p_p->ps_flags, PS_PLEDGE))
> - fdp->fd_ofileflags[indx] |= UF_PLEDGED;
> - wfp->f_count++;
> - fd_used(fdp, indx);
> - return (0);
> + flags |= UF_PLEDGED;
> +
> + /* finishdup() does FRELE */
> + error = finishdup(p, wfp, dupfd, indx, &dummy, 1);
> + if (error == 0)
> + fdp->fd_ofileflags[indx] |= flags;
> + return (error);
> }
>
> /*
