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    SubjectRe: [PATCH v5 5/7] mm, hmm: Use devm semantics for hmm_devmem_{add, remove}
    On Wed, Sep 12, 2018 at 07:22:27PM -0700, Dan Williams wrote:
    > devm semantics arrange for resources to be torn down when
    > device-driver-probe fails or when device-driver-release completes.
    > Similar to devm_memremap_pages() there is no need to support an explicit
    > remove operation when the users properly adhere to devm semantics.
    >
    > Note that devm_kzalloc() automatically handles allocating node-local
    > memory.
    >
    > Reviewed-by: Christoph Hellwig <hch@lst.de>

    Reviewed-by: Jérôme Glisse <jglisse@redhat.com>

    > Cc: Logan Gunthorpe <logang@deltatee.com>
    > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
    > ---
    > include/linux/hmm.h | 4 --
    > mm/hmm.c | 127 ++++++++++-----------------------------------------
    > 2 files changed, 25 insertions(+), 106 deletions(-)
    >
    > diff --git a/include/linux/hmm.h b/include/linux/hmm.h
    > index 4c92e3ba3e16..5ec8635f602c 100644
    > --- a/include/linux/hmm.h
    > +++ b/include/linux/hmm.h
    > @@ -499,8 +499,7 @@ struct hmm_devmem {
    > * enough and allocate struct page for it.
    > *
    > * The device driver can wrap the hmm_devmem struct inside a private device
    > - * driver struct. The device driver must call hmm_devmem_remove() before the
    > - * device goes away and before freeing the hmm_devmem struct memory.
    > + * driver struct.
    > */
    > struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    > struct device *device,
    > @@ -508,7 +507,6 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    > struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
    > struct device *device,
    > struct resource *res);
    > -void hmm_devmem_remove(struct hmm_devmem *devmem);
    >
    > /*
    > * hmm_devmem_page_set_drvdata - set per-page driver data field
    > diff --git a/mm/hmm.c b/mm/hmm.c
    > index c968e49f7a0c..ec1d9eccf176 100644
    > --- a/mm/hmm.c
    > +++ b/mm/hmm.c
    > @@ -939,7 +939,6 @@ static void hmm_devmem_ref_exit(void *data)
    >
    > devmem = container_of(ref, struct hmm_devmem, ref);
    > percpu_ref_exit(ref);
    > - devm_remove_action(devmem->device, &hmm_devmem_ref_exit, data);
    > }
    >
    > static void hmm_devmem_ref_kill(void *data)
    > @@ -950,7 +949,6 @@ static void hmm_devmem_ref_kill(void *data)
    > devmem = container_of(ref, struct hmm_devmem, ref);
    > percpu_ref_kill(ref);
    > wait_for_completion(&devmem->completion);
    > - devm_remove_action(devmem->device, &hmm_devmem_ref_kill, data);
    > }
    >
    > static int hmm_devmem_fault(struct vm_area_struct *vma,
    > @@ -988,7 +986,7 @@ static void hmm_devmem_radix_release(struct resource *resource)
    > mutex_unlock(&hmm_devmem_lock);
    > }
    >
    > -static void hmm_devmem_release(struct device *dev, void *data)
    > +static void hmm_devmem_release(void *data)
    > {
    > struct hmm_devmem *devmem = data;
    > struct resource *resource = devmem->resource;
    > @@ -996,11 +994,6 @@ static void hmm_devmem_release(struct device *dev, void *data)
    > struct zone *zone;
    > struct page *page;
    >
    > - if (percpu_ref_tryget_live(&devmem->ref)) {
    > - dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
    > - percpu_ref_put(&devmem->ref);
    > - }
    > -
    > /* pages are dead and unused, undo the arch mapping */
    > start_pfn = (resource->start & ~(PA_SECTION_SIZE - 1)) >> PAGE_SHIFT;
    > npages = ALIGN(resource_size(resource), PA_SECTION_SIZE) >> PAGE_SHIFT;
    > @@ -1124,19 +1117,6 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
    > return ret;
    > }
    >
    > -static int hmm_devmem_match(struct device *dev, void *data, void *match_data)
    > -{
    > - struct hmm_devmem *devmem = data;
    > -
    > - return devmem->resource == match_data;
    > -}
    > -
    > -static void hmm_devmem_pages_remove(struct hmm_devmem *devmem)
    > -{
    > - devres_release(devmem->device, &hmm_devmem_release,
    > - &hmm_devmem_match, devmem->resource);
    > -}
    > -
    > /*
    > * hmm_devmem_add() - hotplug ZONE_DEVICE memory for device memory
    > *
    > @@ -1164,8 +1144,7 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    >
    > dev_pagemap_get_ops();
    >
    > - devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
    > - GFP_KERNEL, dev_to_node(device));
    > + devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL);
    > if (!devmem)
    > return ERR_PTR(-ENOMEM);
    >
    > @@ -1179,11 +1158,11 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    > ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
    > 0, GFP_KERNEL);
    > if (ret)
    > - goto error_percpu_ref;
    > + return ERR_PTR(ret);
    >
    > - ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref);
    > + ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit, &devmem->ref);
    > if (ret)
    > - goto error_devm_add_action;
    > + return ERR_PTR(ret);
    >
    > size = ALIGN(size, PA_SECTION_SIZE);
    > addr = min((unsigned long)iomem_resource.end,
    > @@ -1203,16 +1182,12 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    >
    > devmem->resource = devm_request_mem_region(device, addr, size,
    > dev_name(device));
    > - if (!devmem->resource) {
    > - ret = -ENOMEM;
    > - goto error_no_resource;
    > - }
    > + if (!devmem->resource)
    > + return ERR_PTR(-ENOMEM);
    > break;
    > }
    > - if (!devmem->resource) {
    > - ret = -ERANGE;
    > - goto error_no_resource;
    > - }
    > + if (!devmem->resource)
    > + return ERR_PTR(-ERANGE);
    >
    > devmem->resource->desc = IORES_DESC_DEVICE_PRIVATE_MEMORY;
    > devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
    > @@ -1221,28 +1196,13 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
    >
    > ret = hmm_devmem_pages_create(devmem);
    > if (ret)
    > - goto error_pages;
    > -
    > - devres_add(device, devmem);
    > + return ERR_PTR(ret);
    >
    > - ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref);
    > - if (ret) {
    > - hmm_devmem_remove(devmem);
    > + ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem);
    > + if (ret)
    > return ERR_PTR(ret);
    > - }
    >
    > return devmem;
    > -
    > -error_pages:
    > - devm_release_mem_region(device, devmem->resource->start,
    > - resource_size(devmem->resource));
    > -error_no_resource:
    > -error_devm_add_action:
    > - hmm_devmem_ref_kill(&devmem->ref);
    > - hmm_devmem_ref_exit(&devmem->ref);
    > -error_percpu_ref:
    > - devres_free(devmem);
    > - return ERR_PTR(ret);
    > }
    > EXPORT_SYMBOL(hmm_devmem_add);
    >
    > @@ -1258,8 +1218,7 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
    >
    > dev_pagemap_get_ops();
    >
    > - devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),
    > - GFP_KERNEL, dev_to_node(device));
    > + devmem = devm_kzalloc(device, sizeof(*devmem), GFP_KERNEL);
    > if (!devmem)
    > return ERR_PTR(-ENOMEM);
    >
    > @@ -1273,12 +1232,12 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
    > ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,
    > 0, GFP_KERNEL);
    > if (ret)
    > - goto error_percpu_ref;
    > + return ERR_PTR(ret);
    >
    > - ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref);
    > + ret = devm_add_action_or_reset(device, hmm_devmem_ref_exit,
    > + &devmem->ref);
    > if (ret)
    > - goto error_devm_add_action;
    > -
    > + return ERR_PTR(ret);
    >
    > devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;
    > devmem->pfn_last = devmem->pfn_first +
    > @@ -1286,59 +1245,21 @@ struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
    >
    > ret = hmm_devmem_pages_create(devmem);
    > if (ret)
    > - goto error_devm_add_action;
    > + return ERR_PTR(ret);
    >
    > - devres_add(device, devmem);
    > + ret = devm_add_action_or_reset(device, hmm_devmem_release, devmem);
    > + if (ret)
    > + return ERR_PTR(ret);
    >
    > - ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref);
    > - if (ret) {
    > - hmm_devmem_remove(devmem);
    > + ret = devm_add_action_or_reset(device, hmm_devmem_ref_kill,
    > + &devmem->ref);
    > + if (ret)
    > return ERR_PTR(ret);
    > - }
    >
    > return devmem;
    > -
    > -error_devm_add_action:
    > - hmm_devmem_ref_kill(&devmem->ref);
    > - hmm_devmem_ref_exit(&devmem->ref);
    > -error_percpu_ref:
    > - devres_free(devmem);
    > - return ERR_PTR(ret);
    > }
    > EXPORT_SYMBOL(hmm_devmem_add_resource);
    >
    > -/*
    > - * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE)
    > - *
    > - * @devmem: hmm_devmem struct use to track and manage the ZONE_DEVICE memory
    > - *
    > - * This will hot-unplug memory that was hotplugged by hmm_devmem_add on behalf
    > - * of the device driver. It will free struct page and remove the resource that
    > - * reserved the physical address range for this device memory.
    > - */
    > -void hmm_devmem_remove(struct hmm_devmem *devmem)
    > -{
    > - resource_size_t start, size;
    > - struct device *device;
    > - bool cdm = false;
    > -
    > - if (!devmem)
    > - return;
    > -
    > - device = devmem->device;
    > - start = devmem->resource->start;
    > - size = resource_size(devmem->resource);
    > -
    > - cdm = devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY;
    > - hmm_devmem_ref_kill(&devmem->ref);
    > - hmm_devmem_ref_exit(&devmem->ref);
    > - hmm_devmem_pages_remove(devmem);
    > -
    > - if (!cdm)
    > - devm_release_mem_region(device, start, size);
    > -}
    > -EXPORT_SYMBOL(hmm_devmem_remove);
    > -
    > /*
    > * A device driver that wants to handle multiple devices memory through a
    > * single fake device can use hmm_device to do so. This is purely a helper
    >

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      Last update: 2018-09-18 22:35    [W:4.408 / U:0.024 seconds]
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