On 2020/8/17 17:11, Martin Wilck wrote: > On Sun, 2020-08-16 at 09:45 +0800, Zhiqiang Liu wrote: >> In vector_foreach_slot_after macro, i is the input var, which >> may have a illegal value (i < 0). So we should add lower boundary >> check in vector_foreach_slot_after macro. >> >> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@xxxxxxxxxx> >> Signed-off-by: lixiaokeng <lixiaokeng@xxxxxxxxxx> >> --- >> libmultipath/vector.h | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) > > Perhaps we should write this instead? I'm unsure if compilers can > optimize away the repeated extra check in all cases. > > #define vector_foreach_slot_after(v,p,i) \ > if ((v) && (int)(i) >= 0) \ > for (; (int)(i) < VECTOR_SIZE(v) && ((p) = (v)->slot[i]); (i)++) > > Regards, > Martin > Thanks for your advice. When I modified the vector_foreach_slot_after func, I just focused on the basic functionality, and the performance is totally not considered. I learn a lesson from your advice. Thanks again. Regards Zhiqiang Liu >> >> diff --git a/libmultipath/vector.h b/libmultipath/vector.h >> index 2862dc2..45dbfc1 100644 >> --- a/libmultipath/vector.h >> +++ b/libmultipath/vector.h >> @@ -38,11 +38,11 @@ typedef struct _vector *vector; >> #define VECTOR_LAST_SLOT(V) (((V) && VECTOR_SIZE(V) > 0) ? (V)- >>> slot[(VECTOR_SIZE(V) - 1)] : NULL) >> >> #define vector_foreach_slot(v,p,i) \ >> - for (i = 0; (v) && (int)i < VECTOR_SIZE(v) && ((p) = (v)- >>> slot[i]); i++) >> + for ((i) = 0; (v) && (int)(i) < VECTOR_SIZE(v) && ((p) = (v)- >>> slot[i]); (i)++) >> #define vector_foreach_slot_after(v,p,i) \ >> - for (; (v) && (int)i < VECTOR_SIZE(v) && ((p) = (v)->slot[i]); >> i++) >> + for (; (v) && (int)(i) < VECTOR_SIZE(v) && (int)(i) >= 0 && >> ((p) = (v)->slot[i]); (i)++) >> #define vector_foreach_slot_backwards(v,p,i) \ >> - for (i = VECTOR_SIZE(v) - 1; (int)i >= 0 && ((p) = (v)- >>> slot[i]); i--) >> + for ((i) = VECTOR_SIZE(v) - 1; (int)(i) >= 0 && ((p) = (v)- >>> slot[i]); (i)--) >> >> #define identity(x) (x) >> /* > > > > . > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
