Re: [Qemu-devel] [PATCH 21/38] ivshmem: Disentangle ivshmem_read()

[Markus Armbruster]

Marc-André Lureau <address@hidden> writes:

> Hi
>
> On Mon, Feb 29, 2016 at 7:40 PM, Markus Armbruster <address@hidden> wrote:
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>  hw/misc/ivshmem.c | 189 
>> +++++++++++++++++++++++++++---------------------------
>>  1 file changed, 96 insertions(+), 93 deletions(-)
>>
>> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
>> index 5d33be4..fc46666 100644
>> --- a/hw/misc/ivshmem.c
>> +++ b/hw/misc/ivshmem.c
>> @@ -564,14 +564,106 @@ static void setup_interrupt(IVShmemState *s, int 
>> vector)
>>      }
>>  }
>>
>> +static void process_msg_shmem(IVShmemState *s, int fd)
>> +{
>> +    Error *err = NULL;
>> +    void *ptr;
>> +
>> +    if (memory_region_is_mapped(&s->ivshmem)) {
>> +        error_report("shm already initialized");
>> +        close(fd);
>> +        return;
>> +    }
>> +
>> +    if (check_shm_size(s, fd, &err) == -1) {
>> +        error_report_err(err);
>> +        close(fd);
>> +        return;
>> +    }
>> +
>> +    /* mmap the region and map into the BAR2 */
>> +    ptr = mmap(0, s->ivshmem_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 
>> 0);
>> +    if (ptr == MAP_FAILED) {
>> +        error_report("Failed to mmap shared memory %s", strerror(errno));
>> +        close(fd);
>> +        return;
>> +    }
>> +    memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s),
>> +                               "ivshmem.bar2", s->ivshmem_size, ptr);
>> +    qemu_set_ram_fd(s->ivshmem.ram_addr, fd);
>> +    vmstate_register_ram(&s->ivshmem, DEVICE(s));
>> +    memory_region_add_subregion(&s->bar, 0, &s->ivshmem);
>> +}
>> +
>> +static void process_msg_disconnect(IVShmemState *s, uint16_t posn)
>> +{
>> +    IVSHMEM_DPRINTF("posn %d has gone away\n", posn);
>> +    close_peer_eventfds(s, posn);
>> +}
>> +
>> +static void process_msg_connect(IVShmemState *s, uint16_t posn, int fd)
>> +{
>> +    Peer *peer = &s->peers[posn];
>> +    int vector;
>> +
>> +    /*
>> +     * The N-th connect message for this peer comes with the file
>> +     * descriptor for vector N-1.  Count messages to find the vector.
>> +     */
>> +    if (peer->nb_eventfds >= s->vectors) {
>> +        error_report("Too many eventfd received, device has %d vectors",
>> +                     s->vectors);
>> +        close(fd);
>> +        return;
>> +    }
>> +    vector = peer->nb_eventfds++;
>> +
>> +    IVSHMEM_DPRINTF("eventfds[%d][%d] = %d\n", posn, vector, fd);
>> +    event_notifier_init_fd(&peer->eventfds[vector], fd);
>> +    fcntl_setfl(fd, O_NONBLOCK); /* msix/irqfd poll non block */
>> +
>> +    if (posn == s->vm_id) {
>> +        setup_interrupt(s, vector);
>> +    }
>> +
>> +    if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>> +        ivshmem_add_eventfd(s, posn, vector);
>> +    }
>> +}
>> +
>> +static void process_msg(IVShmemState *s, int64_t msg, int fd)
>> +{
>> +    IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n", msg, fd);
>> +
>> +    if (msg < -1 || msg > IVSHMEM_MAX_PEERS) {
>> +        error_report("server sent invalid message %" PRId64, msg);
>> +        close(fd);
>> +        return;
>> +    }
>> +
>> +    if (msg == -1) {
>> +        process_msg_shmem(s, fd);
>
> the previous code used to close fd if any, it's worth to keep that imho

I'm blind.  Where?

>> +        return;
>> +    }
>> +
>> +    if (msg >= s->nb_peers) {
>> +        resize_peers(s, msg + 1);
>> +    }
>> +
>> +    if (fd >= 0) {
>> +        process_msg_connect(s, msg, fd);
>> +    } else if (s->vm_id == -1) {
>> +        s->vm_id = msg;
>> +    } else {
>> +        process_msg_disconnect(s, msg);
>> +    }
>> +}
>> +
>>  static void ivshmem_read(void *opaque, const uint8_t *buf, int size)
>>  {
>>      IVShmemState *s = opaque;
>>      int incoming_fd;
>> -    int new_eventfd;
>>      int64_t incoming_posn;
>> -    Error *err = NULL;
>> -    Peer *peer;
>>
>>      if (!fifo_update_and_get_i64(s, buf, size, &incoming_posn)) {
>>          return;
>> @@ -581,96 +673,7 @@ static void ivshmem_read(void *opaque, const uint8_t 
>> *buf, int size)
>>      IVSHMEM_DPRINTF("posn is %" PRId64 ", fd is %d\n",
>>                      incoming_posn, incoming_fd);
>>
>> -    if (incoming_posn < -1 || incoming_posn > IVSHMEM_MAX_PEERS) {
>> -        error_report("server sent invalid message %" PRId64,
>> -                     incoming_posn);
>> -        if (incoming_fd != -1) {
>> -            close(incoming_fd);
>> -        }
>> -        return;
>> -    }
>> -
>> -    if (incoming_posn >= s->nb_peers) {
>> -        resize_peers(s, incoming_posn + 1);
>> -    }
>> -
>> -    peer = &s->peers[incoming_posn];
>> -
>> -    if (incoming_fd == -1) {
>> -        /* if posn is positive and unseen before then this is our posn*/
>> -        if (incoming_posn >= 0 && s->vm_id == -1) {
>> -            /* receive our posn */
>> -            s->vm_id = incoming_posn;
>> -        } else {
>> -            /* otherwise an fd == -1 means an existing peer has gone away */
>> -            IVSHMEM_DPRINTF("posn %" PRId64 " has gone away\n", 
>> incoming_posn);
>> -            close_peer_eventfds(s, incoming_posn);
>> -        }
>> -        return;
>> -    }
>> -
>> -    /* if the position is -1, then it's shared memory region fd */
>> -    if (incoming_posn == -1) {
>> -        void * map_ptr;
>> -
>> -        if (memory_region_is_mapped(&s->ivshmem)) {
>> -            error_report("shm already initialized");
>> -            close(incoming_fd);
>> -            return;
>> -        }
>> -
>> -        if (check_shm_size(s, incoming_fd, &err) == -1) {
>> -            error_report_err(err);
>> -            close(incoming_fd);
>> -            return;
>> -        }
>> -
>> -        /* mmap the region and map into the BAR2 */
>> -        map_ptr = mmap(0, s->ivshmem_size, PROT_READ|PROT_WRITE, MAP_SHARED,
>> -                                                            incoming_fd, 0);
>> -        if (map_ptr == MAP_FAILED) {
>> -            error_report("Failed to mmap shared memory %s", 
>> strerror(errno));
>> -            close(incoming_fd);
>> -            return;
>> -        }
>> -        memory_region_init_ram_ptr(&s->ivshmem, OBJECT(s),
>> -                                   "ivshmem.bar2", s->ivshmem_size, 
>> map_ptr);
>> -        qemu_set_ram_fd(s->ivshmem.ram_addr, incoming_fd);
>> -        vmstate_register_ram(&s->ivshmem, DEVICE(s));
>> -
>> -        IVSHMEM_DPRINTF("guest h/w addr = %p, size = %" PRIu64 "\n",
>> -                        map_ptr, s->ivshmem_size);
>> -
>> -        memory_region_add_subregion(&s->bar, 0, &s->ivshmem);
>> -
>> -        return;
>> -    }
>> -
>> -    /* each peer has an associated array of eventfds, and we keep
>> -     * track of how many eventfds received so far */
>> -    /* get a new eventfd: */
>> -    if (peer->nb_eventfds >= s->vectors) {
>> -        error_report("Too many eventfd received, device has %d vectors",
>> -                     s->vectors);
>> -        close(incoming_fd);
>> -        return;
>> -    }
>> -
>> -    new_eventfd = peer->nb_eventfds++;
>> -
>> -    /* this is an eventfd for a particular peer VM */
>> -    IVSHMEM_DPRINTF("eventfds[%" PRId64 "][%d] = %d\n", incoming_posn,
>> -                    new_eventfd, incoming_fd);
>> -    event_notifier_init_fd(&peer->eventfds[new_eventfd], incoming_fd);
>> -    fcntl_setfl(incoming_fd, O_NONBLOCK); /* msix/irqfd poll non block */
>> -
>> -    if (incoming_posn == s->vm_id) {
>> -        setup_interrupt(s, new_eventfd);
>> -    }
>> -
>> -    if (ivshmem_has_feature(s, IVSHMEM_IOEVENTFD)) {
>> -        ivshmem_add_eventfd(s, incoming_posn, new_eventfd);
>> -    }
>> +    process_msg(s, incoming_posn, incoming_fd);
>
> while at it, you may want to rename incoming_posn to msg for consistency.

I didn't to minimize churn, but you're probably right.  I'll try and see
how the diff comes out.

>>  }
>>
>>  static void ivshmem_check_version(void *opaque, const uint8_t * buf, int 
>> size)
>> --
>> 2.4.3
>>
>>
>
> looks good otherwise

Thanks!