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

kernel test robot
2020-10-27T18:41:52Z

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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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