Hi Bruce
On 11/8/2017 6:28 PM, Bruce Richardson Wrote:
On Wed, Nov 08, 2017 at 06:17:10AM +0000, Jia He wrote:
for the code as follows:
if (condition)
rte_smp_rmb();
else
rte_smp_wmb();
Without this patch, compiler will report this error:
error: 'else' without a previous 'if'
Signed-off-by: Jia He <hejia...@gmail.com>
Signed-off-by: jia...@hxt-semitech.com
---
lib/librte_eal/common/include/arch/arm/rte_atomic_64.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
index 0b70d62..38c3393 100644
--- a/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
+++ b/lib/librte_eal/common/include/arch/arm/rte_atomic_64.h
@@ -43,8 +43,8 @@ extern "C" {
#include "generic/rte_atomic.h"
-#define dsb(opt) { asm volatile("dsb " #opt : : : "memory"); }
-#define dmb(opt) { asm volatile("dmb " #opt : : : "memory"); }
+#define dsb(opt) asm volatile("dsb " #opt : : : "memory");
+#define dmb(opt) asm volatile("dmb " #opt : : : "memory");
Need to remove the trailing ";" I too I think.
Alternatively, to keep the braces, the standard practice is to use
do { ... } while(0)
If trailing ";" is not removed
the code:
if (condition)
rte_smp_rmb();
else
anything();
will be like below after precompiling:
if (condition)
asm volatile("dsb " "ld" : : : "memory");;
else
anything();
Then, the same error - error: 'else' without a previous 'if'
If you choose do/while(0), yes, no errors from compiler.
But the checkpatch will report
WARNING: Single statement macros should not use a do {} while (0) loop
#11: FILE: lib/librte_eal/common/include/arch/arm/rte_atomic_64.h:46:
+#define dsb(opt) do { asm volatile("dsb " #opt : : : "memory"); } while (0)
I searched the kernel codes, the marco dsb() didn't use the do/while(0).
Which one do you think is better for dpdk?
Cheers,
Jia
