On Sat, Dec 10, 2022 at 08:43:47AM +0530, Sumit Semwal wrote:
> Hi Christian,
>
> On Fri, 9 Dec 2022 at 12:45, Christian König
> <ckoenig.leichtzumerken@xxxxxxxxx> wrote:
> >
> > The init order and resulting error handling in dma_buf_export
> > was pretty messy.
> >
> > Subordinate objects like the file and the sysfs kernel objects
> > were initializing and wiring itself up with the object in the
> > wrong order resulting not only in complicating and partially
> > incorrect error handling, but also in publishing only halve
> > initialized DMA-buf objects.
> >
> > Clean this up thoughtfully by allocating the file independent
> > of the DMA-buf object. Then allocate and initialize the DMA-buf
> > object itself, before publishing it through sysfs. If everything
> > works as expected the file is then connected with the DMA-buf
> > object and publish it through debugfs.
> >
> > Also adds the missing dma_resv_fini() into the error handling.
> >
> > v2: add some missing changes to dma_bug_getfile() and a missing NULL
> > check in dma_buf_file_release()
> >
> > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
>
> Thank you for this nice cleanup.
> Acked-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
For reasons that aren't clear to me this ended up in drm-misc-fixes, but
doesn't have a Fixes: or cc: stable tag, and because it missed the merge
window it now wont go into any stable releases.
So either this isn't a fix and should have landed in drm-misc-next or so,
or it was, and then it should have had Fixes: line (and cc: stable most
likely too).
I spotted this becaue it caused a conflict in drm-tip that was left behind
unresovled. I fixed it up.
Tsk :-)
-Daniel
>
> Best,
> Sumit.
> > ---
> > drivers/dma-buf/dma-buf-sysfs-stats.c | 7 +--
> > drivers/dma-buf/dma-buf-sysfs-stats.h | 4 +-
> > drivers/dma-buf/dma-buf.c | 84 +++++++++++++--------------
> > 3 files changed, 43 insertions(+), 52 deletions(-)
> >
> > diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.c b/drivers/dma-buf/dma-buf-sysfs-stats.c
> > index 2bba0babcb62..4b680e10c15a 100644
> > --- a/drivers/dma-buf/dma-buf-sysfs-stats.c
> > +++ b/drivers/dma-buf/dma-buf-sysfs-stats.c
> > @@ -168,14 +168,11 @@ void dma_buf_uninit_sysfs_statistics(void)
> > kset_unregister(dma_buf_stats_kset);
> > }
> >
> > -int dma_buf_stats_setup(struct dma_buf *dmabuf)
> > +int dma_buf_stats_setup(struct dma_buf *dmabuf, struct file *file)
> > {
> > struct dma_buf_sysfs_entry *sysfs_entry;
> > int ret;
> >
> > - if (!dmabuf || !dmabuf->file)
> > - return -EINVAL;
> > -
> > if (!dmabuf->exp_name) {
> > pr_err("exporter name must not be empty if stats needed\n");
> > return -EINVAL;
> > @@ -192,7 +189,7 @@ int dma_buf_stats_setup(struct dma_buf *dmabuf)
> >
> > /* create the directory for buffer stats */
> > ret = kobject_init_and_add(&sysfs_entry->kobj, &dma_buf_ktype, NULL,
> > - "%lu", file_inode(dmabuf->file)->i_ino);
> > + "%lu", file_inode(file)->i_ino);
> > if (ret)
> > goto err_sysfs_dmabuf;
> >
> > diff --git a/drivers/dma-buf/dma-buf-sysfs-stats.h b/drivers/dma-buf/dma-buf-sysfs-stats.h
> > index a49c6e2650cc..7a8a995b75ba 100644
> > --- a/drivers/dma-buf/dma-buf-sysfs-stats.h
> > +++ b/drivers/dma-buf/dma-buf-sysfs-stats.h
> > @@ -13,7 +13,7 @@
> > 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_stats_setup(struct dma_buf *dmabuf, struct file *file);
> >
> > void dma_buf_stats_teardown(struct dma_buf *dmabuf);
> > #else
> > @@ -25,7 +25,7 @@ static inline int dma_buf_init_sysfs_statistics(void)
> >
> > static inline void dma_buf_uninit_sysfs_statistics(void) {}
> >
> > -static inline int dma_buf_stats_setup(struct dma_buf *dmabuf)
> > +static inline int dma_buf_stats_setup(struct dma_buf *dmabuf, struct file *file)
> > {
> > return 0;
> > }
> > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> > index e6f36c014c4c..eb6b59363c4f 100644
> > --- a/drivers/dma-buf/dma-buf.c
> > +++ b/drivers/dma-buf/dma-buf.c
> > @@ -95,10 +95,11 @@ static int dma_buf_file_release(struct inode *inode, struct file *file)
> > return -EINVAL;
> >
> > dmabuf = file->private_data;
> > -
> > - mutex_lock(&db_list.lock);
> > - list_del(&dmabuf->list_node);
> > - mutex_unlock(&db_list.lock);
> > + if (dmabuf) {
> > + mutex_lock(&db_list.lock);
> > + list_del(&dmabuf->list_node);
> > + mutex_unlock(&db_list.lock);
> > + }
> >
> > return 0;
> > }
> > @@ -523,17 +524,17 @@ static inline int is_dma_buf_file(struct file *file)
> > return file->f_op == &dma_buf_fops;
> > }
> >
> > -static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
> > +static struct file *dma_buf_getfile(size_t size, int flags)
> > {
> > static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
> > - struct file *file;
> > struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
> > + struct file *file;
> >
> > if (IS_ERR(inode))
> > return ERR_CAST(inode);
> >
> > - inode->i_size = dmabuf->size;
> > - inode_set_bytes(inode, dmabuf->size);
> > + inode->i_size = size;
> > + inode_set_bytes(inode, size);
> >
> > /*
> > * The ->i_ino acquired from get_next_ino() is not unique thus
> > @@ -547,8 +548,6 @@ static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags)
> > flags, &dma_buf_fops);
> > if (IS_ERR(file))
> > goto err_alloc_file;
> > - file->private_data = dmabuf;
> > - file->f_path.dentry->d_fsdata = dmabuf;
> >
> > return file;
> >
> > @@ -614,19 +613,11 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
> > size_t alloc_size = sizeof(struct dma_buf);
> > int ret;
> >
> > - if (!exp_info->resv)
> > - alloc_size += sizeof(struct dma_resv);
> > - else
> > - /* prevent &dma_buf[1] == dma_buf->resv */
> > - alloc_size += 1;
> > -
> > - if (WARN_ON(!exp_info->priv
> > - || !exp_info->ops
> > - || !exp_info->ops->map_dma_buf
> > - || !exp_info->ops->unmap_dma_buf
> > - || !exp_info->ops->release)) {
> > + if (WARN_ON(!exp_info->priv || !exp_info->ops
> > + || !exp_info->ops->map_dma_buf
> > + || !exp_info->ops->unmap_dma_buf
> > + || !exp_info->ops->release))
> > return ERR_PTR(-EINVAL);
> > - }
> >
> > if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
> > (exp_info->ops->pin || exp_info->ops->unpin)))
> > @@ -638,10 +629,21 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
> > if (!try_module_get(exp_info->owner))
> > return ERR_PTR(-ENOENT);
> >
> > + file = dma_buf_getfile(exp_info->size, exp_info->flags);
> > + if (IS_ERR(file)) {
> > + ret = PTR_ERR(file);
> > + goto err_module;
> > + }
> > +
> > + if (!exp_info->resv)
> > + alloc_size += sizeof(struct dma_resv);
> > + else
> > + /* prevent &dma_buf[1] == dma_buf->resv */
> > + alloc_size += 1;
> > dmabuf = kzalloc(alloc_size, GFP_KERNEL);
> > if (!dmabuf) {
> > ret = -ENOMEM;
> > - goto err_module;
> > + goto err_file;
> > }
> >
> > dmabuf->priv = exp_info->priv;
> > @@ -653,44 +655,36 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
> > init_waitqueue_head(&dmabuf->poll);
> > dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
> > dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
> > + mutex_init(&dmabuf->lock);
> > + INIT_LIST_HEAD(&dmabuf->attachments);
> >
> > if (!resv) {
> > - resv = (struct dma_resv *)&dmabuf[1];
> > - dma_resv_init(resv);
> > + dmabuf->resv = (struct dma_resv *)&dmabuf[1];
> > + dma_resv_init(dmabuf->resv);
> > + } else {
> > + dmabuf->resv = resv;
> > }
> > - dmabuf->resv = resv;
> >
> > - file = dma_buf_getfile(dmabuf, exp_info->flags);
> > - if (IS_ERR(file)) {
> > - ret = PTR_ERR(file);
> > + ret = dma_buf_stats_setup(dmabuf, file);
> > + if (ret)
> > goto err_dmabuf;
> > - }
> >
> > + file->private_data = dmabuf;
> > + file->f_path.dentry->d_fsdata = dmabuf;
> > dmabuf->file = file;
> >
> > - mutex_init(&dmabuf->lock);
> > - INIT_LIST_HEAD(&dmabuf->attachments);
> > -
> > mutex_lock(&db_list.lock);
> > list_add(&dmabuf->list_node, &db_list.head);
> > mutex_unlock(&db_list.lock);
> >
> > - ret = dma_buf_stats_setup(dmabuf);
> > - if (ret)
> > - goto err_sysfs;
> > -
> > return dmabuf;
> >
> > -err_sysfs:
> > - /*
> > - * Set file->f_path.dentry->d_fsdata to NULL so that when
> > - * dma_buf_release() gets invoked by dentry_ops, it exits
> > - * early before calling the release() dma_buf op.
> > - */
> > - file->f_path.dentry->d_fsdata = NULL;
> > - fput(file);
> > err_dmabuf:
> > + if (!resv)
> > + dma_resv_fini(dmabuf->resv);
> > kfree(dmabuf);
> > +err_file:
> > + fput(file);
> > err_module:
> > module_put(exp_info->owner);
> > return ERR_PTR(ret);
> > --
> > 2.34.1
> >
>
>
> --
> Thanks and regards,
>
> Sumit Semwal (he / him)
> Tech Lead - LCG, Vertical Technologies
> Linaro.org │ Open source software for ARM SoCs
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
