From ed63bb1d1f8469586006a9ca63c42344401aa2ab Mon Sep 17 00:00:00 2001 From: Greg Hackmann Date: Thu, 13 Jun 2019 15:34:06 -0700 Subject: dma-buf: give each buffer a full-fledged inode By traversing /proc/*/fd and /proc/*/map_files, processes with CAP_ADMIN can get a lot of fine-grained data about how shmem buffers are shared among processes. stat(2) on each entry gives the caller a unique ID (st_ino), the buffer's size (st_size), and even the number of pages currently charged to the buffer (st_blocks / 512). In contrast, all dma-bufs share the same anonymous inode. So while we can count how many dma-buf fds or mappings a process has, we can't get the size of the backing buffers or tell if two entries point to the same dma-buf. On systems with debugfs, we can get a per-buffer breakdown of size and reference count, but can't tell which processes are actually holding the references to each buffer. Replace the singleton inode with full-fledged inodes allocated by alloc_anon_inode(). This involves creating and mounting a mini-pseudo-filesystem for dma-buf, following the example in fs/aio.c. Signed-off-by: Greg Hackmann Signed-off-by: Chenbo Feng Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/20190613223408.139221-2-fengc@google.com --- include/uapi/linux/magic.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index f8c00045d537..665e18627f78 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -91,5 +91,6 @@ #define UDF_SUPER_MAGIC 0x15013346 #define BALLOON_KVM_MAGIC 0x13661366 #define ZSMALLOC_MAGIC 0x58295829 +#define DMA_BUF_MAGIC 0x444d4142 /* "DMAB" */ #endif /* __LINUX_MAGIC_H__ */ -- cgit v1.2.3 From bb2bb903042517b8fb17b2bc21e00512f2dcac01 Mon Sep 17 00:00:00 2001 From: Greg Hackmann Date: Thu, 13 Jun 2019 15:34:07 -0700 Subject: dma-buf: add DMA_BUF_SET_NAME ioctls This patch adds complimentary DMA_BUF_SET_NAME ioctls, which lets userspace processes attach a free-form name to each buffer. This information can be extremely helpful for tracking and accounting shared buffers. For example, on Android, we know what each buffer will be used for at allocation time: GL, multimedia, camera, etc. The userspace allocator can use DMA_BUF_SET_NAME to associate that information with the buffer, so we can later give developers a breakdown of how much memory they're allocating for graphics, camera, etc. Signed-off-by: Greg Hackmann Signed-off-by: Chenbo Feng Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/20190613223408.139221-3-fengc@google.com --- include/uapi/linux/dma-buf.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h index d75df5210a4a..dbc7092e04b5 100644 --- a/include/uapi/linux/dma-buf.h +++ b/include/uapi/linux/dma-buf.h @@ -35,7 +35,10 @@ struct dma_buf_sync { #define DMA_BUF_SYNC_VALID_FLAGS_MASK \ (DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END) +#define DMA_BUF_NAME_LEN 32 + #define DMA_BUF_BASE 'b' #define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) +#define DMA_BUF_SET_NAME _IOW(DMA_BUF_BASE, 1, const char *) #endif -- cgit v1.2.3