linux-kernel - Re: [PATCH 3/9] vt: selection, remove 2 local variables from set_selection

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Date:   Fri, 6 Mar 2020 08:37:45 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jiri Slaby <jslaby@...e.cz>
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] vt: selection, remove 2 local variables from
 set_selection_kernel

On Mon, Feb 24, 2020 at 10:26:50AM +0100, Jiri Slaby wrote:
> On 21. 02. 20, 10:32, Greg KH wrote:
> > On Wed, Feb 19, 2020 at 08:39:45AM +0100, Jiri Slaby wrote:
> >> multiplier and mode are not actually needed:
> >> * multiplier is used only in kmalloc_array, so use "use_unicode ? 4 : 1"
> >>   directly
> >> * mode is used only to assign a bool in this manner:
> >>   if (cond)
> >>     x = true;
> >>   else
> >>     x = false;
> >>   So do "x = cond" directly.
> >>
> >> Signed-off-by: Jiri Slaby <jslaby@...e.cz>
> >> ---
> >>  drivers/tty/vt/selection.c | 14 +++++---------
> >>  1 file changed, 5 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
> >> index 714992693974..6541c09d8bba 100644
> >> --- a/drivers/tty/vt/selection.c
> >> +++ b/drivers/tty/vt/selection.c
> >> @@ -191,9 +191,9 @@ int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
> >>  	struct vc_data *vc = vc_cons[fg_console].d;
> >>  	int new_sel_start, new_sel_end, spc;
> >>  	char *bp, *obp;
> >> -	int i, ps, pe, multiplier;
> >> +	int i, ps, pe;
> >>  	u32 c;
> >> -	int mode, ret = 0;
> >> +	int ret = 0;
> >>  
> >>  	poke_blanked_console();
> >>  
> >> @@ -224,11 +224,7 @@ int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
> >>  		clear_selection();
> >>  		sel_cons = vc_cons[fg_console].d;
> >>  	}
> >> -	mode = vt_do_kdgkbmode(fg_console);
> >> -	if (mode == K_UNICODE)
> >> -		use_unicode = 1;
> >> -	else
> >> -		use_unicode = 0;
> >> +	use_unicode = vt_do_kdgkbmode(fg_console) == K_UNICODE;
> >>  
> >>  	switch (v->sel_mode)
> >>  	{
> >> @@ -312,8 +308,8 @@ int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
> >>  	sel_end = new_sel_end;
> >>  
> >>  	/* Allocate a new buffer before freeing the old one ... */
> >> -	multiplier = use_unicode ? 4 : 1;  /* chars can take up to 4 bytes */
> >> -	bp = kmalloc_array((sel_end - sel_start) / 2 + 1, multiplier,
> >> +	/* chars can take up to 4 bytes with unicode */
> >> +	bp = kmalloc_array((sel_end - sel_start) / 2 + 1, use_unicode ? 4 : 1,
> >>  			   GFP_KERNEL);
> >>  	if (!bp) {
> >>  		printk(KERN_WARNING "selection: kmalloc() failed\n");
> >> -- 
> >> 2.25.0
> >>
> > 
> > This patch fails to apply to my tree, so I stopped here.  Can you rebase
> > and resend the rest of these?
> 
> Could you be a little bit more specific? After the rebase, it still
> applies cleanly for me. Perhaps the tree you are applying this to was
> missing this 5.6-rc3 commit:
> commit 07e6124a1a46b4b5a9b3cacc0c306b50da87abf5
> Author: Jiri Slaby <jslaby@...e.cz>
> Date:   Mon Feb 10 09:11:31 2020 +0100
> 
>     vt: selection, close sel_buffer race
> ?

Yes, I did not have your other patches in the branch I was using, as
those were to go to Linus for this current release.

I've fixed this up now and applied the rest, thanks.

greg k-h