[Qemu-devel] Re: [PATCH] hw/ivshmem.c don't check for negative values on unsigned data types

[Cam Macdonell <cam@cs.ualberta.ca>]

On Tue, Aug 31, 2010 at 9:56 PM, Cam Macdonell <cam@cs.ualberta.ca> wrote:
> On Tue, Aug 31, 2010 at 6:51 PM, Hao, Xudong <xudong.hao@intel.com> wrote:
>> Hao, Xudong wrote:
>>> Jes.Sorensen@redhat.com wrote:
>>>> From: Jes Sorensen <Jes.Sorensen@redhat.com>
>>>>
>>>> There is no need to check for dest < 0 or vector >= 0 as both are
>>>> uint16_t.
>>>>
>>>> This should fix problems with broken build with aggressive compiler
>>>> flags. Reported by Xudong Hao <xudong.hao@intel.com>
>>>>
>>>> Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com> ---
>>>>  hw/ivshmem.c |    4 ++--
>>>>  1 files changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
>>>> index bbb5cba..afebbc3 100644
>>>> --- a/hw/ivshmem.c
>>>> +++ b/hw/ivshmem.c
>>>> @@ -199,13 +199,13 @@ static void ivshmem_io_writel(void *opaque,
>>>> target_phys_addr_t addr,
>>>>
>>>>          case DOORBELL:
>>>>              /* check that dest VM ID is reasonable */
>>>> -            if ((dest < 0) || (dest > s->max_peer)) {
>>>> +            if (dest > s->max_peer) {
>>>>                  IVSHMEM_DPRINTF("Invalid destination VM ID (%d)\n",
>>>>                  dest); break;
>>>>              }
>>>>
>>>>              /* check doorbell range */
>>>> -            if ((vector >= 0) && (vector <
>>>> s->peers[dest].nb_eventfds)) { +            if (vector <
>>>>                  s->peers[dest].nb_eventfds) {
>>>>
>>>>                  IVSHMEM_DPRINTF("Writing %" PRId64 " to VM %d on
>>>> vector %d\n", write_one, dest, vector); if
>>>> (write(s->peers[dest].eventfds[vector],
>>>
>>> This patch works for me.
>>>
>>
>> Jes, correct result is this patch works for me on x86_64 system. However, in i386 system, there is another bug:
>>
>> ...
>>  CC    x86_64-softmmu/ivshmem.o
>>  CC    x86_64-softmmu/fpu/softfloat-native.o
>>  CC    x86_64-softmmu/op_helper.o
>> cc1: warnings being treated as errors
>> /home/build/gitrepo/qemu/hw/ivshmem.c: In function 'check_shm_size.
>> /home/build/gitrepo/qemu/hw/ivshmem.c:357: warning: format '%ld' expects type 'long int', but argt 5 has type '__off64_t
>> make[1]: *** [ivshmem.o] Error 1
>> make[1]: *** Waiting for unfinished jobs....
>> make: *** [subdir-x86_64-softmmu] Error 2
>
> Hmm, that was causing problems on 32-bit systems, not 64-bit.  Is this
> with gcc 4.1.2?

Oh sorry, I read too fast, you did say it was on 32-bit.  Avi's patch
will do the trick.

Cam