Hi David,

I love your patch! Yet something to improve:

[auto build test ERROR on vfio/next]
[also build test ERROR on vhost/linux-next linus/master kvm/linux-next 
v5.10-rc1 next-20201027]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    
https://github.com/0day-ci/linux/commits/David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
base:   https://github.com/awilliam/linux-vfio.git next
config: x86_64-randconfig-s021-20201027 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.3-56-gc09e8239-dirty
        # 
https://github.com/0day-ci/linux/commit/dc45dd9af28fede8f8dd29b705b90f78cf87538c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review 
David-Woodhouse/Allow-in-kernel-consumers-to-drain-events-from-eventfd/20201027-215658
        git checkout dc45dd9af28fede8f8dd29b705b90f78cf87538c
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

   arch/x86/kvm/../../../virt/kvm/eventfd.c: In function 'irqfd_wakeup':
>> arch/x86/kvm/../../../virt/kvm/eventfd.c:197:23: error: passing argument 1 
>> of 'eventfd_ctx_do_read' from incompatible pointer type 
>> [-Werror=incompatible-pointer-types]
     197 |   eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
         |                       ^~~~~~~~~~~~~~~
         |                       |
         |                       struct eventfd_ctx **
   In file included from arch/x86/kvm/../../../virt/kvm/eventfd.c:21:
   include/linux/eventfd.h:44:46: note: expected 'struct eventfd_ctx *' but 
argument is of type 'struct eventfd_ctx **'
      44 | void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
         |                          ~~~~~~~~~~~~~~~~~~~~^~~
   cc1: some warnings being treated as errors

vim +/eventfd_ctx_do_read +197 arch/x86/kvm/../../../virt/kvm/eventfd.c

   180  
   181  /*
   182   * Called with wqh->lock held and interrupts disabled
   183   */
   184  static int
   185  irqfd_wakeup(wait_queue_entry_t *wait, unsigned mode, int sync, void 
*key)
   186  {
   187          struct kvm_kernel_irqfd *irqfd =
   188                  container_of(wait, struct kvm_kernel_irqfd, wait);
   189          __poll_t flags = key_to_poll(key);
   190          struct kvm_kernel_irq_routing_entry irq;
   191          struct kvm *kvm = irqfd->kvm;
   192          unsigned seq;
   193          int idx;
   194  
   195          if (flags & EPOLLIN) {
   196                  u64 cnt;
 > 197                  eventfd_ctx_do_read(&irqfd->eventfd, &cnt);
   198  
   199                  idx = srcu_read_lock(&kvm->irq_srcu);
   200                  do {
   201                          seq = read_seqcount_begin(&irqfd->irq_entry_sc);
   202                          irq = irqfd->irq_entry;
   203                  } while (read_seqcount_retry(&irqfd->irq_entry_sc, 
seq));
   204                  /* An event has been signaled, inject an interrupt */
   205                  if (kvm_arch_set_irq_inatomic(&irq, kvm,
   206                                                
KVM_USERSPACE_IRQ_SOURCE_ID, 1,
   207                                                false) == -EWOULDBLOCK)
   208                          schedule_work(&irqfd->inject);
   209                  srcu_read_unlock(&kvm->irq_srcu, idx);
   210          }
   211  
   212          if (flags & EPOLLHUP) {
   213                  /* The eventfd is closing, detach from KVM */
   214                  unsigned long iflags;
   215  
   216                  spin_lock_irqsave(&kvm->irqfds.lock, iflags);
   217  
   218                  /*
   219                   * We must check if someone deactivated the irqfd before
   220                   * we could acquire the irqfds.lock since the item is
   221                   * deactivated from the KVM side before it is unhooked 
from
   222                   * the wait-queue.  If it is already deactivated, we can
   223                   * simply return knowing the other side will cleanup 
for us.
   224                   * We cannot race against the irqfd going away since the
   225                   * other side is required to acquire wqh->lock, which 
we hold
   226                   */
   227                  if (irqfd_is_active(irqfd))
   228                          irqfd_deactivate(irqfd);
   229  
   230                  spin_unlock_irqrestore(&kvm->irqfds.lock, iflags);
   231          }
   232  
   233          return 0;
   234  }
   235  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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