From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: drivers/base/devres: introduce devm_release_action()
Patch series "mm/devm_memremap_pages: Fix page release race", v2.
Logan audited the devm_memremap_pages() shutdown path and noticed that it
was possible to proceed to arch_remove_memory() before all potential page
references have been reaped.
Introduce a new ->cleanup() callback to do the work of waiting for any
straggling page references and then perform the percpu_ref_exit() in
devm_memremap_pages_release() context.
For p2pdma this involves some deeper reworks to reference count resources
on a per-instance basis rather than a per pci-device basis. A modified
genalloc api is introduced to convey a driver-private pointer through
gen_pool_{alloc,free}() interfaces. Also, a devm_memunmap_pages() api is
introduced since p2pdma does not auto-release resources on a setup
failure.
The dax and pmem changes pass the nvdimm unit tests, and the p2pdma
changes should now pass testing with the pci_p2pdma_release() fix. Jrme,
how does this look for HMM?
This patch (of 6):
The devm_add_action() facility allows a resource allocation routine to add
custom devm semantics. One such user is devm_memremap_pages().
There is now a need to manually trigger devm_memremap_pages_release().
Introduce devm_release_action() so the release action can be triggered via
a new devm_memunmap_pages() api in a follow-on change.
Link: http://lkml.kernel.org/r/155727336530.292046.2926860263201336366.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/devres.c | 24 +++++++++++++++++++++++-
include/linux/device.h | 1 +
2 files changed, 24 insertions(+), 1 deletion(-)
--- a/drivers/base/devres.c~drivers-base-devres-introduce-devm_release_action
+++ a/drivers/base/devres.c
@@ -755,10 +755,32 @@ void devm_remove_action(struct device *d
WARN_ON(devres_destroy(dev, devm_action_release, devm_action_match,
&devres));
-
}
EXPORT_SYMBOL_GPL(devm_remove_action);
+/**
+ * devm_release_action() - release previously added custom action
+ * @dev: Device that owns the action
+ * @action: Function implementing the action
+ * @data: Pointer to data passed to @action implementation
+ *
+ * Releases and removes instance of @action previously added by
+ * devm_add_action(). Both action and data should match one of the
+ * existing entries.
+ */
+void devm_release_action(struct device *dev, void (*action)(void *), void *data)
+{
+ struct action_devres devres = {
+ .data = data,
+ .action = action,
+ };
+
+ WARN_ON(devres_release(dev, devm_action_release, devm_action_match,
+ &devres));
+
+}
+EXPORT_SYMBOL_GPL(devm_release_action);
+
/*
* Managed kmalloc/kfree
*/
--- a/include/linux/device.h~drivers-base-devres-introduce-devm_release_action
+++ a/include/linux/device.h
@@ -713,6 +713,7 @@ void __iomem *devm_of_iomap(struct devic
/* allows to add/remove a custom action to devres stack */
int devm_add_action(struct device *dev, void (*action)(void *), void *data);
void devm_remove_action(struct device *dev, void (*action)(void *), void *data);
+void devm_release_action(struct device *dev, void (*action)(void *), void *data);
static inline int devm_add_action_or_reset(struct device *dev,
void (*action)(void *), void *data)
_
