On 3/4/23 22:17, Jonathan Cameron wrote:
On Thu, 2 Mar 2023 12:58:59 +0200
Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
As per other branch of the thread.
ch0 = max(1, le16_to_cpu(res[0]);
> would be cleaner.
I tried this out. Comparing u16 to literal 1 results comparison of
values with different sizes:
./include/linux/minmax.h:20:28: warning: comparison of distinct pointer
types lacks a cast
(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
^
./include/linux/minmax.h:26:4: note: in expansion of macro ‘__typecheck’
(__typecheck(x, y) && __no_side_effects(x, y))
^~~~~~~~~~~
./include/linux/minmax.h:36:24: note: in expansion of macro ‘__safe_cmp’
__builtin_choose_expr(__safe_cmp(x, y), \
^~~~~~~~~~
./include/linux/minmax.h:74:19: note: in expansion of macro ‘__careful_cmp’
#define max(x, y) __careful_cmp(x, y, >)
^~~~~~~~~~~~~
drivers/iio/light/rohm-bu27034.c:1057:8: note: in expansion of macro ‘max’
ch0 = max(1, ch0);
I could work around this by doing:
const u16 min_ch_val = 1;
...
ch0 = max(min_ch_val, le16_to_cpu(res[0]));
but I think that would really be obfuscating the meaning. I assume
ch0 = max((u16)1, le16_to_cpu(res[0]));
might work too - but to me it's pretty ugly.
The more I am looking at this, the stronger I feel we should really just
write this as it was. Check if res[0] contains the only unsafe data
"!res[0]" - and if yes, set it to 1. The comment above it will clarify
it to a reader wondering what happens.
I will leave it like it was in v2 for v3. If you still feel strong about
it then we need to continue rubbing it.
Yours,
-- Matti
--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland
~~ When things go utterly wrong vim users can always type :help! ~~
