xen: xen-pciback: Remove create_workqueue
System workqueues have been able to handle high level of concurrency for a long time now and there's no reason to use dedicated workqueues just to gain concurrency. Replace dedicated xen_pcibk_wq with the use of system_wq. Unlike a dedicated per-cpu workqueue created with create_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantees unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference. Since the work items could be pending, flush_work() has been used in xen_pcibk_disconnect(). xen_pcibk_xenbus_remove() calls free_pdev() which in turn calls xen_pcibk_disconnect() for every pdev to ensure that there is no pending task while disconnecting the driver. Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
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@ -55,7 +55,6 @@ struct xen_pcibk_dev_data {
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/* Used by XenBus and xen_pcibk_ops.c */
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/* Used by XenBus and xen_pcibk_ops.c */
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extern wait_queue_head_t xen_pcibk_aer_wait_queue;
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extern wait_queue_head_t xen_pcibk_aer_wait_queue;
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extern struct workqueue_struct *xen_pcibk_wq;
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/* Used by pcistub.c and conf_space_quirks.c */
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/* Used by pcistub.c and conf_space_quirks.c */
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extern struct list_head xen_pcibk_quirks;
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extern struct list_head xen_pcibk_quirks;
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@ -310,7 +310,7 @@ void xen_pcibk_test_and_schedule_op(struct xen_pcibk_device *pdev)
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* already processing a request */
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* already processing a request */
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if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags)
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if (test_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags)
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&& !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) {
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&& !test_and_set_bit(_PDEVF_op_active, &pdev->flags)) {
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queue_work(xen_pcibk_wq, &pdev->op_work);
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schedule_work(&pdev->op_work);
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}
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}
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/*_XEN_PCIB_active should have been cleared by pcifront. And also make
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/*_XEN_PCIB_active should have been cleared by pcifront. And also make
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sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
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sure xen_pcibk is waiting for ack by checking _PCIB_op_pending*/
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@ -17,7 +17,6 @@
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#include "pciback.h"
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#include "pciback.h"
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#define INVALID_EVTCHN_IRQ (-1)
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#define INVALID_EVTCHN_IRQ (-1)
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struct workqueue_struct *xen_pcibk_wq;
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static bool __read_mostly passthrough;
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static bool __read_mostly passthrough;
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module_param(passthrough, bool, S_IRUGO);
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module_param(passthrough, bool, S_IRUGO);
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@ -76,8 +75,7 @@ static void xen_pcibk_disconnect(struct xen_pcibk_device *pdev)
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/* If the driver domain started an op, make sure we complete it
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/* If the driver domain started an op, make sure we complete it
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* before releasing the shared memory */
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* before releasing the shared memory */
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/* Note, the workqueue does not use spinlocks at all.*/
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flush_work(&pdev->op_work);
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flush_workqueue(xen_pcibk_wq);
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if (pdev->sh_info != NULL) {
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if (pdev->sh_info != NULL) {
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xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
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xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_info);
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@ -733,11 +731,6 @@ const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend;
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int __init xen_pcibk_xenbus_register(void)
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int __init xen_pcibk_xenbus_register(void)
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{
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{
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xen_pcibk_wq = create_workqueue("xen_pciback_workqueue");
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if (!xen_pcibk_wq) {
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pr_err("%s: create xen_pciback_workqueue failed\n", __func__);
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return -EFAULT;
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}
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xen_pcibk_backend = &xen_pcibk_vpci_backend;
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xen_pcibk_backend = &xen_pcibk_vpci_backend;
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if (passthrough)
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if (passthrough)
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xen_pcibk_backend = &xen_pcibk_passthrough_backend;
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xen_pcibk_backend = &xen_pcibk_passthrough_backend;
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@ -747,6 +740,5 @@ int __init xen_pcibk_xenbus_register(void)
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void __exit xen_pcibk_xenbus_unregister(void)
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void __exit xen_pcibk_xenbus_unregister(void)
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{
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{
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destroy_workqueue(xen_pcibk_wq);
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xenbus_unregister_driver(&xen_pcibk_driver);
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xenbus_unregister_driver(&xen_pcibk_driver);
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}
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}
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