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ANDROID: fixup dma_buf struct to avoid ABI breakage

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Wrap dma_buf into dma_buf_ext object containing additional num_unique_refs
field required for dmabuf PSS accounting.

Bug: 424648392
Change-Id: I3929ec2cf7cda2626452b5c80949aecefec900e6
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan
2025-07-03 22:25:54 +00:00
parent 59af12872d
commit e9f7ac1c25
3 changed files with 28 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/dma-buf/dma-buf.c
View File

@@ -93,6 +93,7 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
static void dma_buf_release(struct dentry *dentry)
{
struct dma_buf_ext *dmabuf_ext;
struct dma_buf *dmabuf;
dmabuf = dentry->d_fsdata;
@@ -115,13 +116,13 @@ static void dma_buf_release(struct dentry *dentry)
if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
dma_resv_fini(dmabuf->resv);
if (atomic64_read(&dmabuf->num_unique_refs))
dmabuf_ext = get_dmabuf_ext(dmabuf);
if (atomic64_read(&dmabuf_ext->num_unique_refs))
pr_err("destroying dmabuf with non-zero task refs\n");
WARN_ON(!list_empty(&dmabuf->attachments));
module_put(dmabuf->owner);
kfree(dmabuf->name);
kfree(dmabuf);
kfree(dmabuf_ext);
}
static int dma_buf_file_release(struct inode *inode, struct file *file)
@@ -221,8 +222,7 @@ static int new_task_dmabuf_record(struct task_struct *task, struct dma_buf *dmab
rec->dmabuf = dmabuf;
rec->refcnt = 1;
list_add(&rec->node, &dmabuf_info->dmabufs);
atomic64_inc(&dmabuf->num_unique_refs);
atomic64_inc(&get_dmabuf_ext(dmabuf)->num_unique_refs);
return 0;
}
@@ -312,7 +312,7 @@ void dma_buf_unaccount_task(struct dma_buf *dmabuf, struct task_struct *task)
list_del(&rec->node);
kfree(rec);
dmabuf_info->rss -= dmabuf->size;
atomic64_dec(&dmabuf->num_unique_refs);
atomic64_dec(&get_dmabuf_ext(dmabuf)->num_unique_refs);
}
err:
spin_unlock(&dmabuf_info->lock);
@@ -831,10 +831,11 @@ err_alloc_file:
*/
struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
{
struct dma_buf_ext *dmabuf_ext;
struct dma_buf *dmabuf;
struct dma_resv *resv = exp_info->resv;
struct file *file;
size_t alloc_size = sizeof(struct dma_buf);
size_t alloc_size = sizeof(struct dma_buf_ext);
int ret;
if (WARN_ON(!exp_info->priv || !exp_info->ops
@@ -864,12 +865,13 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
else
/* prevent &dma_buf[1] == dma_buf->resv */
alloc_size += 1;
dmabuf = kzalloc(alloc_size, GFP_KERNEL);
if (!dmabuf) {
dmabuf_ext = kzalloc(alloc_size, GFP_KERNEL);
if (!dmabuf_ext) {
ret = -ENOMEM;
goto err_file;
}
dmabuf = &dmabuf_ext->dmabuf;
dmabuf->priv = exp_info->priv;
dmabuf->ops = exp_info->ops;
dmabuf->size = exp_info->size;
@@ -888,7 +890,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
dmabuf->resv = resv;
}
atomic64_set(&dmabuf->num_unique_refs, 0);
atomic64_set(&dmabuf_ext->num_unique_refs, 0);
file->private_data = dmabuf;
file->f_path.dentry->d_fsdata = dmabuf;

2
fs/proc/base.c
View File

@@ -3437,7 +3437,7 @@ static int proc_dmabuf_pss_show(struct seq_file *m, struct pid_namespace *ns,
spin_lock(&dmabuf_info->lock);
list_for_each_entry(rec, &dmabuf_info->dmabufs, node) {
s64 refs = atomic64_read(&rec->dmabuf->num_unique_refs);
s64 refs = atomic64_read(&get_dmabuf_ext(rec->dmabuf)->num_unique_refs);
if (refs <= 0) {
pr_err("dmabuf has <= refs %lld\n", refs);

17
include/linux/dma-buf.h
View File

@@ -535,6 +535,11 @@ struct dma_buf {
} *sysfs_entry;
#endif
ANDROID_KABI_RESERVE(1);
ANDROID_KABI_RESERVE(2);
};
struct dma_buf_ext {
/**
* @num_unique_refs:
*
@@ -542,10 +547,18 @@ struct dma_buf {
*/
atomic64_t num_unique_refs;
ANDROID_KABI_RESERVE(1);
ANDROID_KABI_RESERVE(2);
/*
* dma_buf can have a reservation object after it, so keep this member
* at the end of this structure.
*/
struct dma_buf dmabuf;
};
static inline struct dma_buf_ext *get_dmabuf_ext(struct dma_buf *dmabuf)
{
return container_of(dmabuf, struct dma_buf_ext, dmabuf);
}
/**
* struct dma_buf_attach_ops - importer operations for an attachment
*