Re: [PATCH 3/3] kvm/eventfd: Drain events from eventfd in irqfd_wakeup()

[kernel test robot <lkp@intel.com>]

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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 <lkp@intel.com>

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/kbuild-all@lists.01.org

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