The quilt patch titled
Subject: dax/bus.c: replace driver-core lock usage by a local rwsem
has been removed from the -mm tree. Its filename was
dax-busc-replace-driver-core-lock-usage-by-a-local-rwsem.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Subject: dax/bus.c: replace driver-core lock usage by a local rwsem
Date: Wed, 24 Jan 2024 12:03:46 -0800
Patch series "Add DAX ABI for memmap_on_memory", v7.
This series adds sysfs ABI to control memmap_on_memory behavior for DAX
devices.
Patch 1 replaces incorrect device_lock() usage with a local rwsem - this
was identified during review.
Patch 2 is also a preparatory patch that replaces sprintf() for sysfs
operations with sysfs_emit()
Patch 3 adds the missing documentation for the sysfs ABI for DAX regions
and Dax devices.
Patch 4 exports mhp_supports_memmap_on_memory().
Patch 5 adds the new ABI for toggling memmap_on_memory semantics for dax
devices.
This patch (of 5):
The dax driver incorrectly used driver-core device locks to protect
internal dax region and dax device configuration structures. Replace the
device lock usage with a local rwsem, one each for dax region
configuration and dax device configuration. As a result of this
conversion, no device_lock() usage remains in dax/bus.c.
Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-0-20d16cb8d23d@xxxxxxxxx
Link: https://lkml.kernel.org/r/20240124-vv-dax_abi-v7-1-20d16cb8d23d@xxxxxxxxx
Signed-off-by: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Reported-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Li Zhijian <lizhijian@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/dax/bus.c | 218 +++++++++++++++++++++++++++++++-------------
1 file changed, 156 insertions(+), 62 deletions(-)
--- a/drivers/dax/bus.c~dax-busc-replace-driver-core-lock-usage-by-a-local-rwsem
+++ a/drivers/dax/bus.c
@@ -12,6 +12,18 @@
static DEFINE_MUTEX(dax_bus_lock);
+/*
+ * All changes to the dax region configuration occur with this lock held
+ * for write.
+ */
+DECLARE_RWSEM(dax_region_rwsem);
+
+/*
+ * All changes to the dax device configuration occur with this lock held
+ * for write.
+ */
+DECLARE_RWSEM(dax_dev_rwsem);
+
#define DAX_NAME_LEN 30
struct dax_id {
struct list_head list;
@@ -180,7 +192,7 @@ static u64 dev_dax_size(struct dev_dax *
u64 size = 0;
int i;
- device_lock_assert(&dev_dax->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_dev_rwsem));
for (i = 0; i < dev_dax->nr_range; i++)
size += range_len(&dev_dax->ranges[i].range);
@@ -194,8 +206,15 @@ static int dax_bus_probe(struct device *
struct dev_dax *dev_dax = to_dev_dax(dev);
struct dax_region *dax_region = dev_dax->region;
int rc;
+ u64 size;
- if (dev_dax_size(dev_dax) == 0 || dev_dax->id < 0)
+ rc = down_read_interruptible(&dax_dev_rwsem);
+ if (rc)
+ return rc;
+ size = dev_dax_size(dev_dax);
+ up_read(&dax_dev_rwsem);
+
+ if (size == 0 || dev_dax->id < 0)
return -ENXIO;
rc = dax_drv->probe(dev_dax);
@@ -283,7 +302,7 @@ static unsigned long long dax_region_ava
resource_size_t size = resource_size(&dax_region->res);
struct resource *res;
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
for_each_dax_region_resource(dax_region, res)
size -= resource_size(res);
@@ -295,10 +314,13 @@ static ssize_t available_size_show(struc
{
struct dax_region *dax_region = dev_get_drvdata(dev);
unsigned long long size;
+ int rc;
- device_lock(dev);
+ rc = down_read_interruptible(&dax_region_rwsem);
+ if (rc)
+ return rc;
size = dax_region_avail_size(dax_region);
- device_unlock(dev);
+ up_read(&dax_region_rwsem);
return sprintf(buf, "%llu\n", size);
}
@@ -314,10 +336,12 @@ static ssize_t seed_show(struct device *
if (is_static(dax_region))
return -EINVAL;
- device_lock(dev);
+ rc = down_read_interruptible(&dax_region_rwsem);
+ if (rc)
+ return rc;
seed = dax_region->seed;
rc = sprintf(buf, "%s\n", seed ? dev_name(seed) : "");
- device_unlock(dev);
+ up_read(&dax_region_rwsem);
return rc;
}
@@ -333,14 +357,18 @@ static ssize_t create_show(struct device
if (is_static(dax_region))
return -EINVAL;
- device_lock(dev);
+ rc = down_read_interruptible(&dax_region_rwsem);
+ if (rc)
+ return rc;
youngest = dax_region->youngest;
rc = sprintf(buf, "%s\n", youngest ? dev_name(youngest) : "");
- device_unlock(dev);
+ up_read(&dax_region_rwsem);
return rc;
}
+static struct dev_dax *__devm_create_dev_dax(struct dev_dax_data *data);
+
static ssize_t create_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t len)
{
@@ -358,7 +386,9 @@ static ssize_t create_store(struct devic
if (val != 1)
return -EINVAL;
- device_lock(dev);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return rc;
avail = dax_region_avail_size(dax_region);
if (avail == 0)
rc = -ENOSPC;
@@ -369,7 +399,7 @@ static ssize_t create_store(struct devic
.id = -1,
.memmap_on_memory = false,
};
- struct dev_dax *dev_dax = devm_create_dev_dax(&data);
+ struct dev_dax *dev_dax = __devm_create_dev_dax(&data);
if (IS_ERR(dev_dax))
rc = PTR_ERR(dev_dax);
@@ -387,7 +417,7 @@ static ssize_t create_store(struct devic
rc = len;
}
}
- device_unlock(dev);
+ up_write(&dax_region_rwsem);
return rc;
}
@@ -417,7 +447,7 @@ static void trim_dev_dax_range(struct de
struct range *range = &dev_dax->ranges[i].range;
struct dax_region *dax_region = dev_dax->region;
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
dev_dbg(&dev_dax->dev, "delete range[%d]: %#llx:%#llx\n", i,
(unsigned long long)range->start,
(unsigned long long)range->end);
@@ -435,7 +465,7 @@ static void free_dev_dax_ranges(struct d
trim_dev_dax_range(dev_dax);
}
-static void unregister_dev_dax(void *dev)
+static void __unregister_dev_dax(void *dev)
{
struct dev_dax *dev_dax = to_dev_dax(dev);
@@ -447,6 +477,17 @@ static void unregister_dev_dax(void *dev
put_device(dev);
}
+static void unregister_dev_dax(void *dev)
+{
+ if (rwsem_is_locked(&dax_region_rwsem))
+ return __unregister_dev_dax(dev);
+
+ if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0))
+ return;
+ __unregister_dev_dax(dev);
+ up_write(&dax_region_rwsem);
+}
+
static void dax_region_free(struct kref *kref)
{
struct dax_region *dax_region;
@@ -463,11 +504,10 @@ static void dax_region_put(struct dax_re
/* a return value >= 0 indicates this invocation invalidated the id */
static int __free_dev_dax_id(struct dev_dax *dev_dax)
{
- struct device *dev = &dev_dax->dev;
struct dax_region *dax_region;
int rc = dev_dax->id;
- device_lock_assert(dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_dev_rwsem));
if (!dev_dax->dyn_id || dev_dax->id < 0)
return -1;
@@ -480,12 +520,13 @@ static int __free_dev_dax_id(struct dev_
static int free_dev_dax_id(struct dev_dax *dev_dax)
{
- struct device *dev = &dev_dax->dev;
int rc;
- device_lock(dev);
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc)
+ return rc;
rc = __free_dev_dax_id(dev_dax);
- device_unlock(dev);
+ up_write(&dax_dev_rwsem);
return rc;
}
@@ -519,8 +560,14 @@ static ssize_t delete_store(struct devic
if (!victim)
return -ENXIO;
- device_lock(dev);
- device_lock(victim);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return rc;
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc) {
+ up_write(&dax_region_rwsem);
+ return rc;
+ }
dev_dax = to_dev_dax(victim);
if (victim->driver || dev_dax_size(dev_dax))
rc = -EBUSY;
@@ -541,12 +588,12 @@ static ssize_t delete_store(struct devic
} else
rc = -EBUSY;
}
- device_unlock(victim);
+ up_write(&dax_dev_rwsem);
/* won the race to invalidate the device, clean it up */
if (do_del)
devm_release_action(dev, unregister_dev_dax, victim);
- device_unlock(dev);
+ up_write(&dax_region_rwsem);
put_device(victim);
return rc;
@@ -658,16 +705,15 @@ static void dax_mapping_release(struct d
put_device(parent);
}
-static void unregister_dax_mapping(void *data)
+static void __unregister_dax_mapping(void *data)
{
struct device *dev = data;
struct dax_mapping *mapping = to_dax_mapping(dev);
struct dev_dax *dev_dax = to_dev_dax(dev->parent);
- struct dax_region *dax_region = dev_dax->region;
dev_dbg(dev, "%s\n", __func__);
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
dev_dax->ranges[mapping->range_id].mapping = NULL;
mapping->range_id = -1;
@@ -675,28 +721,37 @@ static void unregister_dax_mapping(void
device_unregister(dev);
}
+static void unregister_dax_mapping(void *data)
+{
+ if (rwsem_is_locked(&dax_region_rwsem))
+ return __unregister_dax_mapping(data);
+
+ if (WARN_ON_ONCE(down_write_killable(&dax_region_rwsem) != 0))
+ return;
+ __unregister_dax_mapping(data);
+ up_write(&dax_region_rwsem);
+}
+
static struct dev_dax_range *get_dax_range(struct device *dev)
{
struct dax_mapping *mapping = to_dax_mapping(dev);
struct dev_dax *dev_dax = to_dev_dax(dev->parent);
- struct dax_region *dax_region = dev_dax->region;
+ int rc;
- device_lock(dax_region->dev);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return NULL;
if (mapping->range_id < 0) {
- device_unlock(dax_region->dev);
+ up_write(&dax_region_rwsem);
return NULL;
}
return &dev_dax->ranges[mapping->range_id];
}
-static void put_dax_range(struct dev_dax_range *dax_range)
+static void put_dax_range(void)
{
- struct dax_mapping *mapping = dax_range->mapping;
- struct dev_dax *dev_dax = to_dev_dax(mapping->dev.parent);
- struct dax_region *dax_region = dev_dax->region;
-
- device_unlock(dax_region->dev);
+ up_write(&dax_region_rwsem);
}
static ssize_t start_show(struct device *dev,
@@ -709,7 +764,7 @@ static ssize_t start_show(struct device
if (!dax_range)
return -ENXIO;
rc = sprintf(buf, "%#llx\n", dax_range->range.start);
- put_dax_range(dax_range);
+ put_dax_range();
return rc;
}
@@ -725,7 +780,7 @@ static ssize_t end_show(struct device *d
if (!dax_range)
return -ENXIO;
rc = sprintf(buf, "%#llx\n", dax_range->range.end);
- put_dax_range(dax_range);
+ put_dax_range();
return rc;
}
@@ -741,7 +796,7 @@ static ssize_t pgoff_show(struct device
if (!dax_range)
return -ENXIO;
rc = sprintf(buf, "%#lx\n", dax_range->pgoff);
- put_dax_range(dax_range);
+ put_dax_range();
return rc;
}
@@ -775,7 +830,7 @@ static int devm_register_dax_mapping(str
struct device *dev;
int rc;
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
if (dev_WARN_ONCE(&dev_dax->dev, !dax_region->dev->driver,
"region disabled\n"))
@@ -821,7 +876,7 @@ static int alloc_dev_dax_range(struct de
struct resource *alloc;
int i, rc;
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
/* handle the seed alloc special case */
if (!size) {
@@ -875,13 +930,12 @@ static int adjust_dev_dax_range(struct d
{
int last_range = dev_dax->nr_range - 1;
struct dev_dax_range *dax_range = &dev_dax->ranges[last_range];
- struct dax_region *dax_region = dev_dax->region;
bool is_shrink = resource_size(res) > size;
struct range *range = &dax_range->range;
struct device *dev = &dev_dax->dev;
int rc;
- device_lock_assert(dax_region->dev);
+ WARN_ON_ONCE(!rwsem_is_locked(&dax_region_rwsem));
if (dev_WARN_ONCE(dev, !size, "deletion is handled by dev_dax_shrink\n"))
return -EINVAL;
@@ -907,10 +961,13 @@ static ssize_t size_show(struct device *
{
struct dev_dax *dev_dax = to_dev_dax(dev);
unsigned long long size;
+ int rc;
- device_lock(dev);
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc)
+ return rc;
size = dev_dax_size(dev_dax);
- device_unlock(dev);
+ up_write(&dax_dev_rwsem);
return sprintf(buf, "%llu\n", size);
}
@@ -1080,17 +1137,27 @@ static ssize_t size_store(struct device
return -EINVAL;
}
- device_lock(dax_region->dev);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return rc;
if (!dax_region->dev->driver) {
- device_unlock(dax_region->dev);
- return -ENXIO;
+ rc = -ENXIO;
+ goto err_region;
}
- device_lock(dev);
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc)
+ goto err_dev;
+
rc = dev_dax_resize(dax_region, dev_dax, val);
- device_unlock(dev);
- device_unlock(dax_region->dev);
- return rc == 0 ? len : rc;
+err_dev:
+ up_write(&dax_dev_rwsem);
+err_region:
+ up_write(&dax_region_rwsem);
+
+ if (rc == 0)
+ return len;
+ return rc;
}
static DEVICE_ATTR_RW(size);
@@ -1138,18 +1205,24 @@ static ssize_t mapping_store(struct devi
return rc;
rc = -ENXIO;
- device_lock(dax_region->dev);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return rc;
if (!dax_region->dev->driver) {
- device_unlock(dax_region->dev);
+ up_write(&dax_region_rwsem);
+ return rc;
+ }
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc) {
+ up_write(&dax_region_rwsem);
return rc;
}
- device_lock(dev);
to_alloc = range_len(&r);
if (alloc_is_aligned(dev_dax, to_alloc))
rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
- device_unlock(dev);
- device_unlock(dax_region->dev);
+ up_write(&dax_dev_rwsem);
+ up_write(&dax_region_rwsem);
return rc == 0 ? len : rc;
}
@@ -1196,13 +1269,19 @@ static ssize_t align_store(struct device
if (!dax_align_valid(val))
return -EINVAL;
- device_lock(dax_region->dev);
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return rc;
if (!dax_region->dev->driver) {
- device_unlock(dax_region->dev);
+ up_write(&dax_region_rwsem);
return -ENXIO;
}
- device_lock(dev);
+ rc = down_write_killable(&dax_dev_rwsem);
+ if (rc) {
+ up_write(&dax_region_rwsem);
+ return rc;
+ }
if (dev->driver) {
rc = -EBUSY;
goto out_unlock;
@@ -1214,8 +1293,8 @@ static ssize_t align_store(struct device
if (rc)
dev_dax->align = align_save;
out_unlock:
- device_unlock(dev);
- device_unlock(dax_region->dev);
+ up_write(&dax_dev_rwsem);
+ up_write(&dax_region_rwsem);
return rc == 0 ? len : rc;
}
static DEVICE_ATTR_RW(align);
@@ -1325,7 +1404,7 @@ static const struct device_type dev_dax_
.groups = dax_attribute_groups,
};
-struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
+static struct dev_dax *__devm_create_dev_dax(struct dev_dax_data *data)
{
struct dax_region *dax_region = data->dax_region;
struct device *parent = dax_region->dev;
@@ -1440,6 +1519,21 @@ err_id:
return ERR_PTR(rc);
}
+
+struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
+{
+ struct dev_dax *dev_dax;
+ int rc;
+
+ rc = down_write_killable(&dax_region_rwsem);
+ if (rc)
+ return ERR_PTR(rc);
+
+ dev_dax = __devm_create_dev_dax(data);
+ up_write(&dax_region_rwsem);
+
+ return dev_dax;
+}
EXPORT_SYMBOL_GPL(devm_create_dev_dax);
int __dax_driver_register(struct dax_device_driver *dax_drv,
_
Patches currently in -mm which might be from vishal.l.verma@xxxxxxxxx are
