2019-04-27 03:35:52

by Nicholas Mc Guire

[permalink] [raw]
Subject: [PATCH] staging: greybus: use proper return type for wait_for_completion_timeout

wait_for_completion_timeout() returns unsigned long (0 on timeout or
remaining jiffies) not int.

Signed-off-by: Nicholas Mc Guire <[email protected]>
---
Problem located with experimental API conformance checking cocci script

Patch was compile-tested with: x86_64_defconfig + GREYBUS=m

Patch is against 5.1-rc6 (localversion-next is next-20190426)

drivers/staging/greybus/uart.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index b3bffe9..ff18112 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -323,7 +323,7 @@ static int send_break(struct gb_tty *gb_tty, u8 state)

static int gb_uart_wait_for_all_credits(struct gb_tty *gb_tty)
{
- int ret;
+ unsigned long ret;

if (gb_tty->credits == GB_UART_FIRMWARE_CREDITS)
return 0;
--
2.1.4


2019-04-30 10:01:45

by Dan Carpenter

[permalink] [raw]
Subject: Re: [PATCH] staging: greybus: use proper return type for wait_for_completion_timeout

On Sat, Apr 27, 2019 at 05:27:25AM +0200, Nicholas Mc Guire wrote:
> wait_for_completion_timeout() returns unsigned long (0 on timeout or
> remaining jiffies) not int.
>

Yeah, but it's fine though because 10000 / 256 fits into int without a
problem.

I'm not sure this sort of patch is worth it when it's just a style
debate instead of a bugfix. I'm a little bit torn about this. In
Smatch, I run into this issue one in a while where Smatch doesn't know
if the timeout is less than int. Right now I hacked the DB to say that
these functions always return < INT_MAX.

Anyway, for sure the commit message should say that it's just a cleanup
and not a bugfix.

regards,
dan carpenter

2019-04-30 13:03:13

by Nicholas Mc Guire

[permalink] [raw]
Subject: Re: [PATCH] staging: greybus: use proper return type for wait_for_completion_timeout

On Tue, Apr 30, 2019 at 12:58:21PM +0300, Dan Carpenter wrote:
> On Sat, Apr 27, 2019 at 05:27:25AM +0200, Nicholas Mc Guire wrote:
> > wait_for_completion_timeout() returns unsigned long (0 on timeout or
> > remaining jiffies) not int.
> >
>
> Yeah, but it's fine though because 10000 / 256 fits into int without a
> problem.
>
> I'm not sure this sort of patch is worth it when it's just a style
> debate instead of a bugfix. I'm a little bit torn about this. In
> Smatch, I run into this issue one in a while where Smatch doesn't know
> if the timeout is less than int. Right now I hacked the DB to say that
> these functions always return < INT_MAX.
>
> Anyway, for sure the commit message should say that it's just a cleanup
> and not a bugfix.
>
I know its not a functional bug its "only" an API violation - the problem
is more that code is often cut&past and at some point it may be a
problem or someoe expects a negative return value without that this evef
can occure.

But yes - the commit message should have stated that this non-conformance
in this case has no effect - will resend.

thx!
hofrat