RE: [Patch v3 2/2] PCI: hv: Remove unused refcount and supporting functions for handling bus device removal

[Long Li <longli@microsoft.com>]

> Subject: Re: [Patch v3 2/2] PCI: hv: Remove unused refcount and supporting
> functions for handling bus device removal
> 
> On Wed, May 12, 2021 at 01:06:49AM -0700, longli@linuxonhyperv.com
> wrote:
> > From: Long Li <longli@microsoft.com>
> >
> > With the new method of flushing/stopping the workqueue before doing
> > bus removal, the old mechanism of using refcount and wait for
> > completion is no longer needed. Remove those dead code.
> >
> > Signed-off-by: Long Li <longli@microsoft.com>
> > ---
> >  drivers/pci/controller/pci-hyperv.c | 34
> > +++--------------------------
> >  1 file changed, 3 insertions(+), 31 deletions(-)
> 
> I'd be grateful if in the future you can send threaded patch series so that
> tools like b4 can detect the thread and create the mbox accordingly.
> 
> No need to resend this one (maybe I need to trim patch(2) Subject).

Will do next time.  Thank you!

Long

> 
> Thanks,
> Lorenzo
> 
> > diff --git a/drivers/pci/controller/pci-hyperv.c
> > b/drivers/pci/controller/pci-hyperv.c
> > index c6122a1b0c46..9499ae3275fe 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -452,7 +452,6 @@ struct hv_pcibus_device {
> >  	/* Protocol version negotiated with the host */
> >  	enum pci_protocol_version_t protocol_version;
> >  	enum hv_pcibus_state state;
> > -	refcount_t remove_lock;
> >  	struct hv_device *hdev;
> >  	resource_size_t low_mmio_space;
> >  	resource_size_t high_mmio_space;
> > @@ -460,7 +459,6 @@ struct hv_pcibus_device {
> >  	struct resource *low_mmio_res;
> >  	struct resource *high_mmio_res;
> >  	struct completion *survey_event;
> > -	struct completion remove_event;
> >  	struct pci_bus *pci_bus;
> >  	spinlock_t config_lock;	/* Avoid two threads writing index page */
> >  	spinlock_t device_list_lock;	/* Protect lists below */
> > @@ -593,9 +591,6 @@ static void put_pcichild(struct hv_pci_dev *hpdev)
> >  		kfree(hpdev);
> >  }
> >
> > -static void get_hvpcibus(struct hv_pcibus_device *hv_pcibus); -static
> > void put_hvpcibus(struct hv_pcibus_device *hv_pcibus);
> > -
> >  /*
> >   * There is no good way to get notified from vmbus_onoffer_rescind(),
> >   * so let's use polling here, since this is not a hot path.
> > @@ -2067,10 +2062,8 @@ static void pci_devices_present_work(struct
> work_struct *work)
> >  	}
> >  	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
> >
> > -	if (!dr) {
> > -		put_hvpcibus(hbus);
> > +	if (!dr)
> >  		return;
> > -	}
> >
> >  	/* First, mark all existing children as reported missing. */
> >  	spin_lock_irqsave(&hbus->device_list_lock, flags); @@ -2153,7
> > +2146,6 @@ static void pci_devices_present_work(struct work_struct
> *work)
> >  		break;
> >  	}
> >
> > -	put_hvpcibus(hbus);
> >  	kfree(dr);
> >  }
> >
> > @@ -2194,12 +2186,10 @@ static int hv_pci_start_relations_work(struct
> hv_pcibus_device *hbus,
> >  	list_add_tail(&dr->list_entry, &hbus->dr_list);
> >  	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
> >
> > -	if (pending_dr) {
> > +	if (pending_dr)
> >  		kfree(dr_wrk);
> > -	} else {
> > -		get_hvpcibus(hbus);
> > +	else
> >  		queue_work(hbus->wq, &dr_wrk->wrk);
> > -	}
> >
> >  	return 0;
> >  }
> > @@ -2342,8 +2332,6 @@ static void hv_eject_device_work(struct
> work_struct *work)
> >  	put_pcichild(hpdev);
> >  	put_pcichild(hpdev);
> >  	/* hpdev has been freed. Do not use it any more. */
> > -
> > -	put_hvpcibus(hbus);
> >  }
> >
> >  /**
> > @@ -2367,7 +2355,6 @@ static void hv_pci_eject_device(struct
> hv_pci_dev *hpdev)
> >  	hpdev->state = hv_pcichild_ejecting;
> >  	get_pcichild(hpdev);
> >  	INIT_WORK(&hpdev->wrk, hv_eject_device_work);
> > -	get_hvpcibus(hbus);
> >  	queue_work(hbus->wq, &hpdev->wrk);
> >  }
> >
> > @@ -2967,17 +2954,6 @@ static int hv_send_resources_released(struct
> hv_device *hdev)
> >  	return 0;
> >  }
> >
> > -static void get_hvpcibus(struct hv_pcibus_device *hbus) -{
> > -	refcount_inc(&hbus->remove_lock);
> > -}
> > -
> > -static void put_hvpcibus(struct hv_pcibus_device *hbus) -{
> > -	if (refcount_dec_and_test(&hbus->remove_lock))
> > -		complete(&hbus->remove_event);
> > -}
> > -
> >  #define HVPCI_DOM_MAP_SIZE (64 * 1024)  static
> > DECLARE_BITMAP(hvpci_dom_map, HVPCI_DOM_MAP_SIZE);
> >
> > @@ -3097,14 +3073,12 @@ static int hv_pci_probe(struct hv_device *hdev,
> >  	hbus->sysdata.domain = dom;
> >
> >  	hbus->hdev = hdev;
> > -	refcount_set(&hbus->remove_lock, 1);
> >  	INIT_LIST_HEAD(&hbus->children);
> >  	INIT_LIST_HEAD(&hbus->dr_list);
> >  	INIT_LIST_HEAD(&hbus->resources_for_children);
> >  	spin_lock_init(&hbus->config_lock);
> >  	spin_lock_init(&hbus->device_list_lock);
> >  	spin_lock_init(&hbus->retarget_msi_interrupt_lock);
> > -	init_completion(&hbus->remove_event);
> >  	hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,
> >  					   hbus->sysdata.domain);
> >  	if (!hbus->wq) {
> > @@ -3341,8 +3315,6 @@ static int hv_pci_remove(struct hv_device *hdev)
> >  	hv_pci_free_bridge_windows(hbus);
> >  	irq_domain_remove(hbus->irq_domain);
> >  	irq_domain_free_fwnode(hbus->sysdata.fwnode);
> > -	put_hvpcibus(hbus);
> > -	wait_for_completion(&hbus->remove_event);
> >
> >  	hv_put_dom_num(hbus->sysdata.domain);
> >
> > --
> > 2.27.0
> >