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Commit 3073774e authored by Serhii Popovych's avatar Serhii Popovych Committed by Paul Mackerras
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KVM: PPC: Book3S HV: Drop prepare_done from struct kvm_resize_hpt 



Currently the kvm_resize_hpt structure has two fields relevant to the
state of an ongoing resize: 'prepare_done', which indicates whether
the worker thread has completed or not, and 'error' which indicates
whether it was successful or not.

Since the success/failure isn't known until completion, this is
confusingly redundant.  This patch consolidates the information into
just the 'error' value: -EBUSY indicates the worked is still in
progress, other negative values indicate (completed) failure, 0
indicates successful completion.

As a bonus 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 which references
a non-existent semaphore (leftover from an early draft).

Assert with WARN_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.

Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: default avatarSerhii Popovych <spopovyc@redhat.com>
[dwg: Changed BUG_ON()s to WARN_ON()s and altered commit message for
 clarity]
Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
parent a63dd748

arch/powerpc/kvm/book3s_64_mmu_hv.c

+27 −17
Original line number Diff line number Diff line
@@ -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;

};
@@ -1433,15 +1439,23 @@ static void resize_hpt_prepare_work(struct work_struct *work) 
	struct kvm *kvm = resize->kvm;

	int err;



	if (WARN_ON(resize->error != -EBUSY))

		return;



	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.

	 */

	if (WARN_ON(err == -EBUSY))

		err = -EINPROGRESS;



	mutex_lock(&kvm->lock);



	resize->error = err;

	resize->prepare_done = true;



	mutex_unlock(&kvm->lock);

}
@@ -1466,14 +1480,12 @@ long kvm_vm_ioctl_resize_hpt_prepare(struct kvm *kvm, 


	if (resize) {

		if (resize->order == shift) {

			/* Suitable resize in progress */

			if (resize->prepare_done) {

			/* Suitable resize in progress? */

			ret = resize->error;

				if (ret != 0)

					resize_hpt_release(kvm, resize);

			} else {

			if (ret == -EBUSY)

				ret = 100; /* estimated time in ms */

			}

			else if (ret)

				resize_hpt_release(kvm, resize);



			goto out;

		}
@@ -1493,6 +1505,8 @@ 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);
@@ -1547,16 +1561,12 @@ 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);