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ANDROID: Add ashmem ioctl to return a unique file identifier

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This will allow a client program to avoid redundant actions on ashmem
buffers which it has already seen.

Bug: 244233389
Change-Id: Ica57a8842ff163eae5f9eca8141b439091ec0940
Signed-off-by: Mark Fasheh <mfasheh@google.com>
This commit is contained in:
Mark Fasheh
2022-10-27 23:48:03 +00:00
parent 3a049b038e
commit 4bc79ed42f
2 changed files with 19 additions and 0 deletions
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18
drivers/staging/android/ashmem.c
View File

@@ -817,6 +817,7 @@ out_unlock:
static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct ashmem_area *asma = file->private_data;
unsigned long ino;
long ret = -ENOTTY;
switch (cmd) {
@@ -860,6 +861,23 @@ static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
ashmem_shrink_scan(&ashmem_shrinker, &sc);
}
break;
case ASHMEM_GET_FILE_ID:
/* Lock around our check to avoid racing with ashmem_mmap(). */
mutex_lock(&ashmem_mutex);
if (!asma || !asma->file) {
mutex_unlock(&ashmem_mutex);
ret = -EINVAL;
break;
}
ino = file_inode(asma->file)->i_ino;
mutex_unlock(&ashmem_mutex);
if (copy_to_user((void __user *)arg, &ino, sizeof(ino))) {
ret = -EFAULT;
break;
}
ret = 0;
break;
}
return ret;

1
drivers/staging/android/uapi/ashmem.h
View File

@@ -39,5 +39,6 @@ struct ashmem_pin {
#define ASHMEM_UNPIN _IOW(__ASHMEMIOC, 8, struct ashmem_pin)
#define ASHMEM_GET_PIN_STATUS _IO(__ASHMEMIOC, 9)
#define ASHMEM_PURGE_ALL_CACHES _IO(__ASHMEMIOC, 10)
#define ASHMEM_GET_FILE_ID _IOR(__ASHMEMIOC, 11, unsigned long)
#endif /* _UAPI_LINUX_ASHMEM_H */