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authorJérôme Glisse <jglisse@redhat.com>2017-09-08 16:12:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-08 18:26:46 -0700
commit858b54dabf4363daa3a97b9a722130a8e7cea8c9 (patch)
treed7603a71e353df51667c57e942c2a2311fed9379 /mm
parent4ef589dc9b10cdcae75a2b2b0e9b2c5e8a92c378 (diff)
download96b-common-858b54dabf4363daa3a97b9a722130a8e7cea8c9.tar.gz
mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory
This introduce a dummy HMM device class so device driver can use it to create hmm_device for the sole purpose of registering device memory. It is useful to device driver that want to manage multiple physical device memory under same struct device umbrella. Link: http://lkml.kernel.org/r/20170817000548.32038-13-jglisse@redhat.com Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com> Signed-off-by: Sherry Cheung <SCheung@nvidia.com> Signed-off-by: Subhash Gutti <sgutti@nvidia.com> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Nellans <dnellans@nvidia.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Bob Liu <liubo95@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hmm.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/mm/hmm.c b/mm/hmm.c
index afb51078a5cf..c9d23ef80552 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -19,6 +19,7 @@
*/
#include <linux/mm.h>
#include <linux/hmm.h>
+#include <linux/init.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/slab.h>
@@ -1096,4 +1097,84 @@ void hmm_devmem_remove(struct hmm_devmem *devmem)
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
+ * and it is not needed to make use of any HMM functionality.
+ */
+#define HMM_DEVICE_MAX 256
+
+static DECLARE_BITMAP(hmm_device_mask, HMM_DEVICE_MAX);
+static DEFINE_SPINLOCK(hmm_device_lock);
+static struct class *hmm_device_class;
+static dev_t hmm_device_devt;
+
+static void hmm_device_release(struct device *device)
+{
+ struct hmm_device *hmm_device;
+
+ hmm_device = container_of(device, struct hmm_device, device);
+ spin_lock(&hmm_device_lock);
+ clear_bit(hmm_device->minor, hmm_device_mask);
+ spin_unlock(&hmm_device_lock);
+
+ kfree(hmm_device);
+}
+
+struct hmm_device *hmm_device_new(void *drvdata)
+{
+ struct hmm_device *hmm_device;
+
+ hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL);
+ if (!hmm_device)
+ return ERR_PTR(-ENOMEM);
+
+ spin_lock(&hmm_device_lock);
+ hmm_device->minor = find_first_zero_bit(hmm_device_mask, HMM_DEVICE_MAX);
+ if (hmm_device->minor >= HMM_DEVICE_MAX) {
+ spin_unlock(&hmm_device_lock);
+ kfree(hmm_device);
+ return ERR_PTR(-EBUSY);
+ }
+ set_bit(hmm_device->minor, hmm_device_mask);
+ spin_unlock(&hmm_device_lock);
+
+ dev_set_name(&hmm_device->device, "hmm_device%d", hmm_device->minor);
+ hmm_device->device.devt = MKDEV(MAJOR(hmm_device_devt),
+ hmm_device->minor);
+ hmm_device->device.release = hmm_device_release;
+ dev_set_drvdata(&hmm_device->device, drvdata);
+ hmm_device->device.class = hmm_device_class;
+ device_initialize(&hmm_device->device);
+
+ return hmm_device;
+}
+EXPORT_SYMBOL(hmm_device_new);
+
+void hmm_device_put(struct hmm_device *hmm_device)
+{
+ put_device(&hmm_device->device);
+}
+EXPORT_SYMBOL(hmm_device_put);
+
+static int __init hmm_init(void)
+{
+ int ret;
+
+ ret = alloc_chrdev_region(&hmm_device_devt, 0,
+ HMM_DEVICE_MAX,
+ "hmm_device");
+ if (ret)
+ return ret;
+
+ hmm_device_class = class_create(THIS_MODULE, "hmm_device");
+ if (IS_ERR(hmm_device_class)) {
+ unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX);
+ return PTR_ERR(hmm_device_class);
+ }
+ return 0;
+}
+
+device_initcall(hmm_init);
#endif /* IS_ENABLED(CONFIG_DEVICE_PRIVATE) */