Re: [PATCH 1/8] NTB: ntb_tool: reading the link file should not end in a NULL byte
From: Serge Semin
Date: Fri Jun 15 2018 - 15:47:45 EST
On Fri, Jun 08, 2018 at 06:08:11PM -0600, Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote:
> When running ntb_test this warning is issued:
> ./ntb_test.sh: line 200: warning: command substitution: ignored null
> byte in input
This is weird. Neither me nor the folks' who tested the script saw this warning.
I tried it on my laptop with bash and on a target device with busybox-shell. The
warning never occurred. I even tried a simple command like:
[[ $(echo -ne "\x4e\x0a\00") == "N" ]] && echo "True"
It might be that your bash is more modern than mine. Anyway if this patch solves the
problem you see, that's great. Thanks for it.
> This is caused by the kernel returning one more byte than is necessary
> when reading the link file.
> Reduce the number of bytes read back to 2 as it was before the
> commit that regressed this.
> Fixes: 7f46c8b3a552 ("NTB: ntb_tool: Add full multi-port NTB API support")
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> drivers/ntb/test/ntb_tool.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
> diff --git a/drivers/ntb/test/ntb_tool.c b/drivers/ntb/test/ntb_tool.c
> index d592c0ffbd19..ec5cf095cdb9 100644
> --- a/drivers/ntb/test/ntb_tool.c
> +++ b/drivers/ntb/test/ntb_tool.c
> @@ -504,7 +504,7 @@ static ssize_t tool_peer_link_read(struct file *filep, char __user *ubuf,
> buf = '\n';
> buf = '\0';
> - return simple_read_from_buffer(ubuf, size, offp, buf, 3);
> + return simple_read_from_buffer(ubuf, size, offp, buf, 2);
> static TOOL_FOPS_RDWR(tool_peer_link_fops,
> @@ -1690,4 +1690,3 @@ static void __exit tool_exit(void)