On 12/10/2015 08:40 PM, Geyslan G. Bem wrote:
Don't use the 'do {} while (0)' wrapper in a single statement macro.
Caught by checkpatch: "WARNING: Single statement macros should not
use a do {} while (0) loop"
Signed-off-by: Geyslan G. Bem <geyslan@xxxxxxxxx>
---
drivers/usb/host/ehci.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index cfeebd8..945000a 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -244,9 +244,9 @@ struct ehci_hcd { /* one per
controller */
/* irq statistics */
#ifdef EHCI_STATS
struct ehci_stats stats;
-# define COUNT(x) do { (x)++; } while (0)
+# define COUNT(x) ((x)++)
#else
-# define COUNT(x) do {} while (0)
+# define COUNT(x) ((void) 0)
Why not just empty #define?
Indeed. I'll change it.
Tks Sergei.
Since COUNT is not used to return the empty #define is ok. Another way
is to use #define COUNT(x) (0) to get a 0 when necessary to read
returns.
Just 0, no parens please.
Ok, no parens, since there's no evaluation.
It's because the literals don't need parens at all.
Then my change is:
-# define COUNT(x) do { (x)++; } while (0)
+# define COUNT(x) (++(x))
#else
-# define COUNT(x) do {} while (0)
+# define COUNT(x) 0
Pre-increment allowing to return the updated x.
Why if there was a post-increment before?
There's nothing wrong with post-increment. The pre one would be
necessary if using return.
Maybe it was intended to return the old value? :-)
Anyway, this talk is quite pointless since the macro didn't return any
value anyway.
You're sure, there's no use anywhere of the return of that macro indeed.
*do* {} *while* (0) just couldn't return any value, it's not just a
compound statement which gcc indeed allows to be evaluated.
Sending v2 soon.
MBR, Sergei
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