dma-buf: Delete the DMA-BUF attachment sysfs statistics

The DMA-BUF attachment statistics form a subset of the DMA-BUF
sysfs statistics that recently merged to the drm-misc tree. They are not
UABI yet since they have not merged to the upstream Linux kernel.

Since there has been a reported a performance regression due to the
overhead of sysfs directory creation/teardown during
dma_buf_attach()/dma_buf_detach(), this patch deletes the DMA-BUF
attachment statistics from sysfs.

Fixes: bdb8d06dfefd ("dmabuf: Add the capability to expose DMA-BUF stats in sysfs")
Signed-off-by: Hridya Valsaraju <hridya@google.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210713040742.2680135-1-hridya@google.com
Signed-off-by: Christian König <christian.koenig@amd.com>

diff --git a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
index a243984ed420adfea4faa3abb6991e9d423c914a..5d3bc997dc6400138012854521044793bc380f0c 100644 (file)
--- a/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
+++ b/Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers
@@ -22,31 +22,3 @@ KernelVersion:       v5.13
 Contact:       Hridya Valsaraju <hridya@google.com>
 Description:   This file is read-only and specifies the size of the DMA-BUF in
                bytes.
-
-What:          /sys/kernel/dmabuf/buffers/<inode_number>/attachments
-Date:          May 2021
-KernelVersion: v5.13
-Contact:       Hridya Valsaraju <hridya@google.com>
-Description:   This directory will contain subdirectories representing every
-               attachment of the DMA-BUF.
-
-What:          /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>
-Date:          May 2021
-KernelVersion: v5.13
-Contact:       Hridya Valsaraju <hridya@google.com>
-Description:   This directory will contain information on the attached device
-               and the number of current distinct device mappings.
-
-What:          /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/device
-Date:          May 2021
-KernelVersion: v5.13
-Contact:       Hridya Valsaraju <hridya@google.com>
-Description:   This file is read-only and is a symlink to the attached device's
-               sysfs entry.
-
-What:          /sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attachment_uid>/map_counter
-Date:          May 2021
-KernelVersion: v5.13
-Contact:       Hridya Valsaraju <hridya@google.com>
-Description:   This file is read-only and contains a map_counter indicating the
-               number of distinct device mappings of the attachment.

diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
index a2638e84199c4494c85a55f0acb36fdec6dcdc28..053baadcada9466e863d028f01e4e97f108aac7c 100644 (file)
--- a/drivers/dma-buf/dma-buf-sysfs-stats.c
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
@@ -40,14 +40,11 @@
  *
  * * ``/sys/kernel/dmabuf/buffers/<inode_number>/exporter_name``
  * * ``/sys/kernel/dmabuf/buffers/<inode_number>/size``
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/device``
- * * ``/sys/kernel/dmabuf/buffers/<inode_number>/attachments/<attach_uid>/map_counter``
  *
- * The information in the interface can also be used to derive per-exporter and
- * per-device usage statistics. The data from the interface can be gathered
- * on error conditions or other important events to provide a snapshot of
- * DMA-BUF usage. It can also be collected periodically by telemetry to monitor
- * various metrics.
+ * The information in the interface can also be used to derive per-exporter
+ * statistics. The data from the interface can be gathered on error conditions
+ * or other important events to provide a snapshot of DMA-BUF usage.
+ * It can also be collected periodically by telemetry to monitor various metrics.
  *
  * Detailed documentation about the interface is present in
  * Documentation/ABI/testing/sysfs-kernel-dmabuf-buffers.
@@ -121,120 +118,6 @@ static struct kobj_type dma_buf_ktype = {
        .default_groups = dma_buf_stats_default_groups,
 };
 
-#define to_dma_buf_attach_entry_from_kobj(x) container_of(x, struct dma_buf_attach_sysfs_entry, kobj)
-
-struct dma_buf_attach_stats_attribute {
-       struct attribute attr;
-       ssize_t (*show)(struct dma_buf_attach_sysfs_entry *sysfs_entry,
-                       struct dma_buf_attach_stats_attribute *attr, char *buf);
-};
-#define to_dma_buf_attach_stats_attr(x) container_of(x, struct dma_buf_attach_stats_attribute, attr)
-
-static ssize_t dma_buf_attach_stats_attribute_show(struct kobject *kobj,
-                                                  struct attribute *attr,
-                                                  char *buf)
-{
-       struct dma_buf_attach_stats_attribute *attribute;
-       struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-       attribute = to_dma_buf_attach_stats_attr(attr);
-       sysfs_entry = to_dma_buf_attach_entry_from_kobj(kobj);
-
-       if (!attribute->show)
-               return -EIO;
-
-       return attribute->show(sysfs_entry, attribute, buf);
-}
-
-static const struct sysfs_ops dma_buf_attach_stats_sysfs_ops = {
-       .show = dma_buf_attach_stats_attribute_show,
-};
-
-static ssize_t map_counter_show(struct dma_buf_attach_sysfs_entry *sysfs_entry,
-                               struct dma_buf_attach_stats_attribute *attr,
-                               char *buf)
-{
-       return sysfs_emit(buf, "%u\n", sysfs_entry->map_counter);
-}
-
-static struct dma_buf_attach_stats_attribute map_counter_attribute =
-       __ATTR_RO(map_counter);
-
-static struct attribute *dma_buf_attach_stats_default_attrs[] = {
-       &map_counter_attribute.attr,
-       NULL,
-};
-ATTRIBUTE_GROUPS(dma_buf_attach_stats_default);
-
-static void dma_buf_attach_sysfs_release(struct kobject *kobj)
-{
-       struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-       sysfs_entry = to_dma_buf_attach_entry_from_kobj(kobj);
-       kfree(sysfs_entry);
-}
-
-static struct kobj_type dma_buf_attach_ktype = {
-       .sysfs_ops = &dma_buf_attach_stats_sysfs_ops,
-       .release = dma_buf_attach_sysfs_release,
-       .default_groups = dma_buf_attach_stats_default_groups,
-};
-
-void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach)
-{
-       struct dma_buf_attach_sysfs_entry *sysfs_entry;
-
-       sysfs_entry = attach->sysfs_entry;
-       if (!sysfs_entry)
-               return;
-
-       sysfs_delete_link(&sysfs_entry->kobj, &attach->dev->kobj, "device");
-
-       kobject_del(&sysfs_entry->kobj);
-       kobject_put(&sysfs_entry->kobj);
-}
-
-int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
-                              unsigned int uid)
-{
-       struct dma_buf_attach_sysfs_entry *sysfs_entry;
-       int ret;
-       struct dma_buf *dmabuf;
-
-       if (!attach)
-               return -EINVAL;
-
-       dmabuf = attach->dmabuf;
-
-       sysfs_entry = kzalloc(sizeof(struct dma_buf_attach_sysfs_entry),
-                             GFP_KERNEL);
-       if (!sysfs_entry)
-               return -ENOMEM;
-
-       sysfs_entry->kobj.kset = dmabuf->sysfs_entry->attach_stats_kset;
-
-       attach->sysfs_entry = sysfs_entry;
-
-       ret = kobject_init_and_add(&sysfs_entry->kobj, &dma_buf_attach_ktype,
-                                  NULL, "%u", uid);
-       if (ret)
-               goto kobj_err;
-
-       ret = sysfs_create_link(&sysfs_entry->kobj, &attach->dev->kobj,
-                               "device");
-       if (ret)
-               goto link_err;
-
-       return 0;
-
-link_err:
-       kobject_del(&sysfs_entry->kobj);
-kobj_err:
-       kobject_put(&sysfs_entry->kobj);
-       attach->sysfs_entry = NULL;
-
-       return ret;
-}
 void dma_buf_stats_teardown(struct dma_buf *dmabuf)
 {
        struct dma_buf_sysfs_entry *sysfs_entry;
@@ -243,7 +126,6 @@ void dma_buf_stats_teardown(struct dma_buf *dmabuf)
        if (!sysfs_entry)
                return;
 
-       kset_unregister(sysfs_entry->attach_stats_kset);
        kobject_del(&sysfs_entry->kobj);
        kobject_put(&sysfs_entry->kobj);
 }
@@ -290,7 +172,6 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
 {
        struct dma_buf_sysfs_entry *sysfs_entry;
        int ret;
-       struct kset *attach_stats_kset;
 
        if (!dmabuf || !dmabuf->file)
                return -EINVAL;
@@ -315,21 +196,8 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
        if (ret)
                goto err_sysfs_dmabuf;
 
-       /* create the directory for attachment stats */
-       attach_stats_kset = kset_create_and_add("attachments",
-                                               &dmabuf_sysfs_no_uevent_ops,
-                                               &sysfs_entry->kobj);
-       if (!attach_stats_kset) {
-               ret = -ENOMEM;
-               goto err_sysfs_attach;
-       }
-
-       sysfs_entry->attach_stats_kset = attach_stats_kset;
-
        return 0;
 
-err_sysfs_attach:
-       kobject_del(&sysfs_entry->kobj);
 err_sysfs_dmabuf:
        kobject_put(&sysfs_entry->kobj);
        dmabuf->sysfs_entry = NULL;

diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
index 5f4703249117ac86472ded082280e9fc0ff60b07..a49c6e2650cccddb5eddf639bca14df89a36050b 100644 (file)
--- a/drivers/dma-buf/dma-buf-sysfs-stats.h
+++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
@@ -14,23 +14,8 @@ int dma_buf_init_sysfs_statistics(void);
 void dma_buf_uninit_sysfs_statistics(void);
 
 int dma_buf_stats_setup(struct dma_buf *dmabuf);
-int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
-                              unsigned int uid);
-static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
-                                                      int delta)
-{
-       struct dma_buf_attach_sysfs_entry *entry = attach->sysfs_entry;
 
-       entry->map_counter += delta;
-}
 void dma_buf_stats_teardown(struct dma_buf *dmabuf);
-void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach);
-static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
-{
-       struct dma_buf_sysfs_entry *entry = dmabuf->sysfs_entry;
-
-       return entry->attachment_uid++;
-}
 #else
 
 static inline int dma_buf_init_sysfs_statistics(void)
@@ -44,19 +29,7 @@ static inline int dma_buf_stats_setup(struct dma_buf *dmabuf)
 {
        return 0;
 }
-static inline int dma_buf_attach_stats_setup(struct dma_buf_attachment *attach,
-                                            unsigned int uid)
-{
-       return 0;
-}
 
 static inline void dma_buf_stats_teardown(struct dma_buf *dmabuf) {}
-static inline void dma_buf_attach_stats_teardown(struct dma_buf_attachment *attach) {}
-static inline void dma_buf_update_attachment_map_count(struct dma_buf_attachment *attach,
-                                                      int delta) {}
-static inline unsigned int dma_buf_update_attach_uid(struct dma_buf *dmabuf)
-{
-       return 0;
-}
 #endif
 #endif // _DMA_BUF_SYSFS_STATS_H

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 510b427719742a539fc401aaf126e7147cb82b3b..b1a6db71c656153c5ea96c331b5f4bdbd393487b 100644 (file)
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -738,7 +738,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
 {
        struct dma_buf_attachment *attach;
        int ret;
-       unsigned int attach_uid;
 
        if (WARN_ON(!dmabuf || !dev))
                return ERR_PTR(-EINVAL);
@@ -764,13 +763,8 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
        }
        dma_resv_lock(dmabuf->resv, NULL);
        list_add(&attach->node, &dmabuf->attachments);
-       attach_uid = dma_buf_update_attach_uid(dmabuf);
        dma_resv_unlock(dmabuf->resv);
 
-       ret = dma_buf_attach_stats_setup(attach, attach_uid);
-       if (ret)
-               goto err_sysfs;
-
        /* When either the importer or the exporter can't handle dynamic
         * mappings we cache the mapping here to avoid issues with the
         * reservation object lock.
@@ -797,7 +791,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
                        dma_resv_unlock(attach->dmabuf->resv);
                attach->sgt = sgt;
                attach->dir = DMA_BIDIRECTIONAL;
-               dma_buf_update_attachment_map_count(attach, 1 /* delta */);
        }
 
        return attach;
@@ -814,7 +807,6 @@ err_unlock:
        if (dma_buf_is_dynamic(attach->dmabuf))
                dma_resv_unlock(attach->dmabuf->resv);
 
-err_sysfs:
        dma_buf_detach(dmabuf, attach);
        return ERR_PTR(ret);
 }
@@ -864,7 +856,6 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
                        dma_resv_lock(attach->dmabuf->resv, NULL);
 
                __unmap_dma_buf(attach, attach->sgt, attach->dir);
-               dma_buf_update_attachment_map_count(attach, -1 /* delta */);
 
                if (dma_buf_is_dynamic(attach->dmabuf)) {
                        dmabuf->ops->unpin(attach);
@@ -878,7 +869,6 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
        if (dmabuf->ops->detach)
                dmabuf->ops->detach(dmabuf, attach);
 
-       dma_buf_attach_stats_teardown(attach);
        kfree(attach);
 }
 EXPORT_SYMBOL_GPL(dma_buf_detach);
@@ -1020,10 +1010,6 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
                }
        }
 #endif /* CONFIG_DMA_API_DEBUG */
-
-       if (!IS_ERR(sg_table))
-               dma_buf_update_attachment_map_count(attach, 1 /* delta */);
-
        return sg_table;
 }
 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
@@ -1061,8 +1047,6 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
        if (dma_buf_is_dynamic(attach->dmabuf) &&
            !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
                dma_buf_unpin(attach);
-
-       dma_buf_update_attachment_map_count(attach, -1 /* delta */);
 }
 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
 

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 2b814fde0d1154c5bde1db3aeceefd6937685880..678b2006be78357b9b25ea52ab84503d50d93218 100644 (file)
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -444,15 +444,6 @@ struct dma_buf {
        struct dma_buf_sysfs_entry {
                struct kobject kobj;
                struct dma_buf *dmabuf;
-
-               /**
-                * @sysfs_entry.attachment_uid:
-                *
-                * This is protected by the dma_resv_lock() on @resv and is
-                * incremented on each attach.
-                */
-               unsigned int attachment_uid;
-               struct kset *attach_stats_kset;
        } *sysfs_entry;
 #endif
 };
@@ -504,7 +495,6 @@ struct dma_buf_attach_ops {
  * @importer_ops: importer operations for this attachment, if provided
  * dma_buf_map/unmap_attachment() must be called with the dma_resv lock held.
  * @importer_priv: importer specific attachment data.
- * @sysfs_entry: For exposing information about this attachment in sysfs.
  *
  * This structure holds the attachment information between the dma_buf buffer
  * and its user device(s). The list contains one attachment struct per device
@@ -525,13 +515,6 @@ struct dma_buf_attachment {
        const struct dma_buf_attach_ops *importer_ops;
        void *importer_priv;
        void *priv;
-#ifdef CONFIG_DMABUF_SYSFS_STATS
-       /* for sysfs stats */
-       struct dma_buf_attach_sysfs_entry {
-               struct kobject kobj;
-               unsigned int map_counter;
-       } *sysfs_entry;
-#endif
 };
 
 /**