Replace ->prepare_done flag functionality with special handling
of -EBUSY in ->error as indicator that allocation work is running.
Besides cosmetics this reduces size of struct kvm_resize_hpt by
__alignof__(struct kvm_hpt_info) and saves few bytes of code.
While there correct comment in struct kvm_resize_hpt about locking
used to protect access to certain fields.
Assert with BUG_ON() in case of HPT allocation thread work runs
more than once for resize request or resize_hpt_allocate()
returns -EBUSY that is treated specially.
Change comparison against zero to make checkpatch.pl happy.
Signed-off-by: Serhii Popovych <spopovyc@xxxxxxxxxx>
---
arch/powerpc/kvm/book3s_64_mmu_hv.c | 42 ++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 17 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 235319c..0534aab 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -65,11 +65,17 @@ struct kvm_resize_hpt {
u32 order;
/* These fields protected by kvm->lock */
+
+ /* Possible values and their usage:
+ * <0 an error occurred during allocation,
+ * -EBUSY allocation is in the progress,
+ * 0 allocation made successfuly.
+ */
int error;
- bool prepare_done;
- /* Private to the work thread, until prepare_done is true,
- * then protected by kvm->resize_hpt_sem */
+ /* Private to the work thread, until error != -EBUSY,
+ * then protected by kvm->lock.
+ */
struct kvm_hpt_info hpt;
};
@@ -1432,15 +1438,21 @@ static void resize_hpt_prepare_work(struct work_struct *work)
struct kvm *kvm = resize->kvm;
int err;
+ BUG_ON(resize->error != -EBUSY);
+
resize_hpt_debug(resize, "resize_hpt_prepare_work(): order = %d\n",
resize->order);
err = resize_hpt_allocate(resize);
+ /* We have strict assumption about -EBUSY
+ * when preparing for HPT resize.
+ */
+ BUG_ON(err == -EBUSY);
+
mutex_lock(&kvm->lock);
resize->error = err;
- resize->prepare_done = true;
mutex_unlock(&kvm->lock);
}
@@ -1465,14 +1477,12 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm,
if (resize) {
if (resize->order == shift) {
- /* Suitable resize in progress */
- if (resize->prepare_done) {
- ret = resize->error;
- if (ret != 0)
- resize_hpt_release(kvm, resize);
- } else {
+ /* Suitable resize in progress? */
+ ret = resize->error;
+ if (ret == -EBUSY)
ret = 100; /* estimated time in ms */
- }
+ else if (ret)
+ resize_hpt_release(kvm, resize);
goto out;
}
@@ -1492,6 +1502,8 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm,
ret = -ENOMEM;
goto out;
}
+
+ resize->error = -EBUSY;
resize->order = shift;
resize->kvm = kvm;
INIT_WORK(&resize->work, resize_hpt_prepare_work);
@@ -1546,16 +1558,12 @@ long kvm_vm_ioctl_resize_hpt_commit(struct kvm *kvm,
if (!resize || (resize->order != shift))
goto out;
- ret = -EBUSY;
- if (!resize->prepare_done)
- goto out;
-
ret = resize->error;
- if (ret != 0)
+ if (ret)
goto out;
ret = resize_hpt_rehash(resize);
- if (ret != 0)
+ if (ret)
goto out;
resize_hpt_pivot(resize);
--
1.8.3.1
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