Re: [Xen-devel] bogus wrap check in xen-netback

[Olaf Hering <olaf@xxxxxxxxx>]

Am Wed, 25 Apr 2018 09:59:23 +0100
schrieb Wei Liu <wei.liu2@xxxxxxxxxx>:

> Do you have the full diff of your changes? 

Not right now. But without 'val', or val being uint, the same error happens in 
f():

#include <stdio.h>
void f(void)
{
        unsigned short req_prod = 0, req_cons = 65400;
        unsigned short val;
        val = req_prod - req_cons;
        printf("req_prod - req_cons %u\n", val);
        printf("req_prod - req_cons %x\n", val);
}

int main(void)
{
#if 1
        unsigned nr_ents = 0x100U, req_prod_pvt = 0x14U, rsp_cons = 
0xffffffeeU, req_prod = 0xfffffffeU;
        unsigned rx_target = 0x40U, qlen = 0x1aU;
#else
        unsigned nr_ents = 0x100U, req_prod_pvt = 0x00U, rsp_cons = 
0xffffffeeU, req_prod = 0xfffffffeU;
        unsigned rx_target = 0x40U, qlen = 0x1aU;
#endif
        printf("batch_target %u, skb_queue_len %u, rx_target %u\n", rx_target - 
(req_prod_pvt - rsp_cons), qlen, rx_target);
        printf("nr_ents %u\n", nr_ents);
        printf("req_prod_pvt - rsp_cons %u\n", req_prod_pvt - rsp_cons);
        printf("req_prod_pvt - req_prod %u\n", req_prod_pvt - req_prod);
        printf("%u\n", nr_ents - (req_prod_pvt - rsp_cons));
        printf("%u\n", nr_ents - (req_prod_pvt - rsp_cons));
        f();
        return 0;
}

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