Re: [PATCH 4/9v2] usb: host: ehci.h: fix single statement macros

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On 12/10/2015 05:56 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?

Anyway, this talk is quite pointless since the macro didn't return any value anyway.

MBR, Sergei

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