Re: [PATCH net 4/4] vhost: log dirty page correctly

Michael S. Tsirkin
2018-12-11T01:30:03Z

On Mon, Dec 10, 2018 at 11:14:41PM +0800, kbuild test robot wrote:
> Hi Jason,
>
> I love your patch! Perhaps something to improve:
>
> [auto build test WARNING on net/master]
>
> url: https://github.com/0day-ci/linux/commits/Jason-Wang/Fix-various-issue-of-vhost/20181210-223236
> config: i386-randconfig-x072-201849 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
> reproduce:
> # save the attached .config to linux build tree
> make ARCH=i386
>
> All warnings (new ones prefixed by >>):
>
> drivers//vhost/vhost.c: In function 'log_used':
> >> drivers//vhost/vhost.c:1771:27: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> ret = translate_desc(vq, (u64)vq->used + used_offset, len, iov, 64,
> ^
> drivers//vhost/vhost.c:1776:27: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> ret = log_write_hva(vq, (u64)iov[i].iov_base, iov[i].iov_len);
> ^
> drivers//vhost/vhost.c: In function 'vhost_log_write':
> drivers//vhost/vhost.c:1788:26: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
> r = log_write_hva(vq, (u64)iov[i].iov_base,
> ^

It's a technicality, cast to unsigned long and the warning will go away.
Donnu why does gcc bother with these warnings. Nothing is wrong
unless size of pointer is > size of int.

> Cyclomatic Complexity 5 include/linux/compiler.h:__read_once_size
> Cyclomatic Complexity 5 include/linux/compiler.h:__write_once_size
> Cyclomatic Complexity 1 arch/x86/include/asm/barrier.h:array_index_mask_nospec
> Cyclomatic Complexity 1 include/linux/kasan-checks.h:kasan_check_read
> Cyclomatic Complexity 1 include/linux/kasan-checks.h:kasan_check_write
> Cyclomatic Complexity 2 arch/x86/include/asm/bitops.h:set_bit
> Cyclomatic Complexity 2 arch/x86/include/asm/bitops.h:clear_bit
> Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:test_and_set_bit
> Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:constant_test_bit
> Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:variable_test_bit
> Cyclomatic Complexity 1 arch/x86/include/asm/bitops.h:fls
> Cyclomatic Complexity 1 include/linux/log2.h:__ilog2_u32
> Cyclomatic Complexity 1 include/linux/list.h:INIT_LIST_HEAD
> Cyclomatic Complexity 1 include/linux/list.h:__list_del
> Cyclomatic Complexity 1 include/linux/list.h:list_empty
> Cyclomatic Complexity 1 arch/x86/include/asm/current.h:get_current
> Cyclomatic Complexity 3 include/linux/string.h:memset
> Cyclomatic Complexity 5 include/linux/string.h:memcpy
> Cyclomatic Complexity 1 include/asm-generic/getorder.h:__get_order
> Cyclomatic Complexity 1 arch/x86/include/asm/atomic.h:arch_atomic_dec_and_test
> Cyclomatic Complexity 1 include/asm-generic/atomic-instrumented.h:atomic_dec_and_test
> Cyclomatic Complexity 1 include/linux/err.h:PTR_ERR
> Cyclomatic Complexity 1 include/linux/thread_info.h:set_ti_thread_flag
> Cyclomatic Complexity 1 include/linux/thread_info.h:check_object_size
> Cyclomatic Complexity 5 include/linux/thread_info.h:check_copy_size
> Cyclomatic Complexity 1 arch/x86/include/asm/preempt.h:preempt_count
> Cyclomatic Complexity 1 include/linux/spinlock.h:spinlock_check
> Cyclomatic Complexity 1 include/linux/spinlock.h:spin_lock
> Cyclomatic Complexity 1 include/linux/spinlock.h:spin_unlock
> Cyclomatic Complexity 1 include/linux/wait.h:init_waitqueue_func_entry
> Cyclomatic Complexity 1 include/linux/llist.h:init_llist_head
> Cyclomatic Complexity 1 include/linux/llist.h:llist_empty
> Cyclomatic Complexity 1 include/linux/llist.h:llist_del_all
> Cyclomatic Complexity 1 include/linux/rbtree.h:rb_link_node
> Cyclomatic Complexity 3 include/linux/overflow.h:__ab_c_size
> Cyclomatic Complexity 1 include/linux/page_ref.h:page_ref_dec_and_test
> Cyclomatic Complexity 1 include/linux/sched.h:task_thread_info
> Cyclomatic Complexity 1 include/linux/sched.h:need_resched
> Cyclomatic Complexity 1 include/linux/mm.h:put_page_testzero
> Cyclomatic Complexity 1 include/linux/mm.h:put_devmap_managed_page
> Cyclomatic Complexity 1 include/uapi/linux/virtio_ring.h:vring_need_event
> Cyclomatic Complexity 1 include/linux/virtio_byteorder.h:virtio_legacy_is_little_endian
> Cyclomatic Complexity 2 include/linux/uio.h:copy_to_iter
> Cyclomatic Complexity 2 include/linux/uio.h:copy_from_iter
> Cyclomatic Complexity 2 include/linux/uio.h:copy_from_iter_full
> Cyclomatic Complexity 1 include/linux/uio.h:iov_iter_count
> Cyclomatic Complexity 1 include/linux/slab.h:kmalloc_type
> Cyclomatic Complexity 28 include/linux/slab.h:kmalloc_index
> Cyclomatic Complexity 67 include/linux/slab.h:kmalloc_large
> Cyclomatic Complexity 4 include/linux/slab.h:kmalloc
> Cyclomatic Complexity 1 arch/x86/include/asm/smap.h:clac
> Cyclomatic Complexity 1 arch/x86/include/asm/smap.h:stac
> Cyclomatic Complexity 1 arch/x86/include/asm/uaccess.h:set_fs
> Cyclomatic Complexity 1 arch/x86/include/asm/uaccess_32.h:raw_copy_to_user
> Cyclomatic Complexity 5 arch/x86/include/asm/uaccess_32.h:raw_copy_from_user
> Cyclomatic Complexity 1 include/linux/uaccess.h:__copy_from_user
> Cyclomatic Complexity 1 include/linux/uaccess.h:__copy_to_user
> Cyclomatic Complexity 2 include/linux/uaccess.h:copy_from_user
> Cyclomatic Complexity 2 include/linux/uaccess.h:copy_to_user
> Cyclomatic Complexity 4 include/linux/poll.h:poll_wait
> Cyclomatic Complexity 1 include/linux/poll.h:init_poll_funcptr
> Cyclomatic Complexity 1 include/linux/rbtree_augmented.h:rb_set_parent
> Cyclomatic Complexity 1 include/linux/rbtree_augmented.h:rb_set_parent_color
> Cyclomatic Complexity 3 include/linux/rbtree_augmented.h:__rb_change_child
> Cyclomatic Complexity 11 include/linux/rbtree_augmented.h:__rb_erase_augmented
> Cyclomatic Complexity 2 include/linux/rbtree_augmented.h:rb_erase_augmented_cached
> Cyclomatic Complexity 1 drivers//vhost/vhost.h:vhost_has_feature
> Cyclomatic Complexity 1 drivers//vhost/vhost.h:vhost_backend_has_feature
> Cyclomatic Complexity 1 drivers//vhost/vhost.h:vhost_is_little_endian
> Cyclomatic Complexity 5 drivers//vhost/vhost.c:vhost_umem_interval_tree_compute_subtree_last
> Cyclomatic Complexity 3 drivers//vhost/vhost.c:vhost_umem_interval_tree_augment_propagate
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_umem_interval_tree_augment_copy
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_umem_interval_tree_augment_rotate
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_umem_interval_tree_remove
> Cyclomatic Complexity 7 drivers//vhost/vhost.c:vhost_umem_interval_tree_subtree_search
> Cyclomatic Complexity 4 drivers//vhost/vhost.c:vhost_umem_interval_tree_iter_first
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_disable_cross_endian
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_enable_cross_endian_big
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_enable_cross_endian_little
> Cyclomatic Complexity 5 drivers//vhost/vhost.c:vhost_set_vring_endian
> Cyclomatic Complexity 2 drivers//vhost/vhost.c:vhost_get_vring_endian
> Cyclomatic Complexity 3 drivers//vhost/vhost.c:vhost_init_is_le
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_reset_is_le
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_work_init
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_poll_init
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_has_work
> Cyclomatic Complexity 2 drivers//vhost/vhost.c:__vhost_vq_meta_reset
> Cyclomatic Complexity 2 drivers//vhost/vhost.c:vhost_vq_meta_reset
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_vq_reset
> Cyclomatic Complexity 2 drivers//vhost/vhost.c:vhost_dev_check_owner
> Cyclomatic Complexity 1 drivers//vhost/vhost.c:vhost_dev_has_owner
>
> vim +1771 drivers//vhost/vhost.c
>
> 1760
> 1761 static void log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
> 1762 {
> 1763 struct iovec iov[64];
> 1764 int i, ret;
> 1765
> 1766 if (!vq->iotlb) {
> 1767 log_write(vq->log_base, vq->log_addr + used_offset, len);
> 1768 return;
> 1769 }
> 1770
> > 1771 ret = translate_desc(vq, (u64)vq->used + used_offset, len, iov, 64,
> 1772 VHOST_ACCESS_WO);
> 1773 WARN_ON(ret < 0);
> 1774
> 1775 for (i = 0; i < ret; i++) {
> 1776 ret = log_write_hva(vq, (u64)iov[i].iov_base, iov[i].iov_len);
> 1777 WARN_ON(ret);
> 1778 }
> 1779 }
> 1780
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
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