range.flags = ...;
range.values = ...;
range.pfn_shift = ...;
+ hmm_range_register(&range);
+
+ /*
+ * Just wait for range to be valid, safe to ignore return value as we
+ * will use the return value of hmm_range_snapshot() below under the
+ * mmap_sem to ascertain the validity of the range.
+ */
+ hmm_range_wait_until_valid(&range, TIMEOUT_IN_MSEC);
again:
down_read(&mm->mmap_sem);
- range.vma = ...;
ret = hmm_range_snapshot(&range);
if (ret) {
up_read(&mm->mmap_sem);
+ if (ret == -EAGAIN) {
+ /*
+ * No need to check hmm_range_wait_until_valid() return value
+ * on retry we will get proper error with hmm_range_snapshot()
+ */
+ hmm_range_wait_until_valid(&range, TIMEOUT_IN_MSEC);
+ goto again;
+ }
+ hmm_mirror_unregister(&range);
return ret;
}
take_lock(driver->update);
- if (!hmm_vma_range_done(vma, &range)) {
+ if (!range.valid) {
release_lock(driver->update);
up_read(&mm->mmap_sem);
goto again;
// Use pfns array content to update device page table
+ hmm_mirror_unregister(&range);
release_lock(driver->update);
up_read(&mm->mmap_sem);
return 0;
}
The driver->update lock is the same lock that the driver takes inside its
-update() callback. That lock must be held before hmm_vma_range_done() to avoid
-any race with a concurrent CPU page table update.
+update() callback. That lock must be held before checking the range.valid
+field to avoid any race with a concurrent CPU page table update.
HMM implements all this on top of the mmu_notifier API because we wanted a
simpler API and also to be able to perform optimizations latter on like doing