Re: [Qemu-devel] [PATCH v2 6/8] ivshmem: generalize ivshmem_setup_interrupts

[Markus Armbruster]

Marc-André Lureau <address@hidden> writes:

> Hi
>
> ----- Original Message -----
>> address@hidden writes:
>> 
>> > From: Marc-André Lureau <address@hidden>
>> >
>> > Call ivshmem_setup_interrupts() with or without MSI, always allocate
>> > msi_vectors that is going to be used in all case in the following patch.
>> >
>> > Signed-off-by: Marc-André Lureau <address@hidden>
>> > ---
>> >  hw/misc/ivshmem.c | 26 ++++++++++++++++----------
>> >  1 file changed, 16 insertions(+), 10 deletions(-)
>> >
>> > diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
>> > index 5029789..c601a8a 100644
>> > --- a/hw/misc/ivshmem.c
>> > +++ b/hw/misc/ivshmem.c
>> > @@ -769,18 +769,25 @@ static void ivshmem_reset(DeviceState *d)
>> >      ivshmem_use_msix(s);
>> >  }
>> >  
>> > -static int ivshmem_setup_msi(IVShmemState * s)
>> > +static int ivshmem_setup_interrupts(IVShmemState *s)
>> >  {
>> > -    if (msix_init_exclusive_bar(PCI_DEVICE(s), s->vectors, 1)) {
>> > -        return -1;
>> > +    /* allocate QEMU callback data for receiving interrupts */
>> > +    if (s->vectors > 0) {
>> > +        s->msi_vectors = g_malloc0(s->vectors * sizeof(MSIVector));
>> > +        if (!s->msi_vectors) {
>> 
>> Can't happen; s->vectors * sizeof(MSIVector) != 0.
>
> It can't happen on allocation failure?

Nope.

Compare g_malloc0() and g_try_malloc0() at
https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html

We generally use the "try" variants only for memory allocations that can
execute during operation and can be "big".