Ping? fs/splice.c:954: warning: ‘ret’ may be used uninitialized in this function The splice syscall explicitly checks for len != 0, but this code is also called from do_sendfile(), where it's difficult to see if len is ever 0. On Mon, Jun 16, 2014 at 9:11 AM, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > Hi Al, > > On Thu, Jun 12, 2014 at 8:14 PM, Linux Kernel Mailing List > <linux-kernel@xxxxxxxxxxxxxxx> wrote: >> Gitweb: http://git.kernel.org/linus/;a=commit;h=8d0207652cbe27d1f962050737848e5ad4671958 >> Commit: 8d0207652cbe27d1f962050737848e5ad4671958 > >> ->splice_write() via ->write_iter() >> >> iter_file_splice_write() - a ->splice_write() instance that gathers the >> pipe buffers, builds a bio_vec-based iov_iter covering those and feeds >> it to ->write_iter(). A bunch of simple cases coverted to that... >> >> [AV: fixed the braino spotted by Cyrill] >> >> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > >> @@ -1052,6 +1053,145 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, >> >> EXPORT_SYMBOL(generic_file_splice_write); >> >> +/** >> + * iter_file_splice_write - splice data from a pipe to a file >> + * @pipe: pipe info >> + * @out: file to write to >> + * @ppos: position in @out >> + * @len: number of bytes to splice >> + * @flags: splice modifier flags >> + * >> + * Description: >> + * Will either move or copy pages (determined by @flags options) from >> + * the given pipe inode to the given file. >> + * This one is ->write_iter-based. > > What's the meaning of the return value? This is not documented. > >> +ssize_t >> +iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, >> + loff_t *ppos, size_t len, unsigned int flags) >> +{ >> + struct splice_desc sd = { >> + .total_len = len, >> + .flags = flags, >> + .pos = *ppos, >> + .u.file = out, >> + }; >> + int nbufs = pipe->buffers; >> + struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), >> + GFP_KERNEL); >> + ssize_t ret; > > fs/splice.c:954: warning: ‘ret’ may be used uninitialized in this function > >> + >> + if (unlikely(!array)) >> + return -ENOMEM; >> + >> + pipe_lock(pipe); >> + >> + splice_from_pipe_begin(&sd); >> + while (sd.total_len) { > > If the "len" parameter is zero, this loop will be skipped, and "ret" will > be uninitialized. > > What should it return? 0? -EINVAL? > >> + } >> +done: >> + kfree(array); >> + splice_from_pipe_end(pipe, &sd); >> + >> + pipe_unlock(pipe); >> + >> + if (sd.num_spliced) >> + ret = sd.num_spliced; >> + >> + return ret; >> +} Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
