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mm, hmm: use devm semantics for hmm_devmem_{add, remove}
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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.

Link: http://lkml.kernel.org/r/154275559545.76910.9186690723515469051.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jérôme Glisse <[email protected]>
Cc: "Jérôme Glisse" <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@djbw @torvalds
djbw authored and torvalds committed Dec 28, 2018
1 parent 69324b8 commit 58ef15b
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Showing 2 changed files with 25 additions and 106 deletions.
4 changes: 1 addition & 3 deletions include/linux/hmm.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -512,16 +512,14 @@ 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,
unsigned long size);
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
Expand Down
127 changes: 24 additions & 103 deletions mm/hmm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -987,7 +987,6 @@ 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)
Expand All @@ -998,7 +997,6 @@ 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,
Expand Down Expand Up @@ -1036,19 +1034,14 @@ 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;
unsigned long start_pfn, npages;
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;
Expand Down Expand Up @@ -1174,19 +1167,6 @@ 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
*
Expand Down Expand Up @@ -1214,8 +1194,7 @@ 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);

Expand All @@ -1229,11 +1208,11 @@ 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,
Expand All @@ -1253,16 +1232,12 @@ 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;
Expand All @@ -1271,28 +1246,13 @@ 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);

Expand All @@ -1308,8 +1268,7 @@ 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);

Expand All @@ -1323,72 +1282,34 @@ 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 +
(resource_size(devmem->resource) >> PAGE_SHIFT);

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
Expand Down

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