On 05. 11. 20, 9:36, Lee Jones wrote:
On Thu, 05 Nov 2020, Jiri Slaby wrote:
On 05. 11. 20, 8:04, Christophe Leroy wrote:
Le 04/11/2020 à 20:35, Lee Jones a écrit :
Fixes the following W=1 kernel build warning(s):
drivers/tty/serial/pmac_zilog.h:365:58: warning: variable
‘garbage’ set but not used [-Wunused-but-set-variable]
Explain how you are fixing this warning.
Setting __always_unused is usually not the good solution for fixing
this warning, but here I guess this is likely the good solution. But it
should be explained why.
There are normally 3 ways to fix this warning;
- Start using/checking the variable/result
- Remove the variable
- Mark it as __{always,maybe}_unused
The later just tells the compiler that not checking the resultant
value is intentional. There are some functions (as Jiri mentions
below) which are marked as '__must_check' which *require* a dummy
(garbage) variable to be used.
Or, why is the "garbage =" needed in the first place? read_zsdata is not
defined with __warn_unused_result__.
I used '__always_used' here for fear of breaking something.
However, if it's safe to remove it, then all the better.
Yes please -- this "garbage" is one of the examples of volatile misuses.
If readb didn't work on volatile pointer, marking the return variable as
volatile wouldn't save it.
And even if it was, would (void)!read_zsdata(port) fix it?
That's hideous. :D
Sure, marking reads as must_check would be insane.
*Much* better to just use '__always_used' in that use-case.
Then using a dummy variable to fool must_check must mean must_check is
used incorrectly, no :)? But there are always exceptions…
thanks,
--
js
suse labs
