From 697b81e9c4b5ba90d31ec4e5fa1b792bfe43ca9c Mon Sep 17 00:00:00 2001 From: Zile Xiong Date: Fri, 20 Mar 2026 14:54:45 +0800 Subject: [PATCH] media: vb2: use ssize_t for vb2_read/vb2_write commit a562d6dc86bdfdd299e1b4734977a8d63e803583 upstream. vb2_read() and vb2_write() return size_t, but propagate negative errno values from __vb2_perform_fileio(). This relies on implicit signed/unsigned conversions in callers (e.g. vb2_fop_read()) to recover error codes: __vb2_perform_fileio() -> -EINVAL vb2_read() -> (size_t)-EINVAL vb2_fop_read() -> -EINVAL This relies on implicit conversions that are not obvious. These helpers are exported (EXPORT_SYMBOL_GPL) and part of the vb2 API, so changing their return type may affect existing users. However, they conceptually follow read/write semantics, where ssize_t is typically used to return either a byte count or a negative error code. Switch vb2_read() and vb2_write() to ssize_t, and update __vb2_perform_fileio() accordingly. Signed-off-by: Zile Xiong Acked-by: Marek Szyprowski Fixes: b25748fe6126 ("[media] v4l: videobuf2: add read() and write() emulator") Cc: stable@vger.kernel.org Signed-off-by: Hans Verkuil Signed-off-by: Greg Kroah-Hartman --- drivers/media/common/videobuf2/videobuf2-core.c | 12 ++++++------ include/media/videobuf2-core.h | 8 ++++---- 2 files changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c index 29bfc2bf796b..1abf6e08668a 100644 --- a/drivers/media/common/videobuf2/videobuf2-core.c +++ b/drivers/media/common/videobuf2/videobuf2-core.c @@ -2769,8 +2769,8 @@ static int __vb2_cleanup_fileio(struct vb2_queue *q) * @nonblock: mode selector (1 means blocking calls, 0 means nonblocking) * @read: access mode selector (1 means read, 0 means write) */ -static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_t count, - loff_t *ppos, int nonblock, int read) +static ssize_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_t count, + loff_t *ppos, int nonblock, int read) { struct vb2_fileio_data *fileio; struct vb2_fileio_buf *buf; @@ -2930,15 +2930,15 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_ return ret; } -size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, - loff_t *ppos, int nonblocking) +ssize_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, + loff_t *ppos, int nonblocking) { return __vb2_perform_fileio(q, data, count, ppos, nonblocking, 1); } EXPORT_SYMBOL_GPL(vb2_read); -size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count, - loff_t *ppos, int nonblocking) +ssize_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count, + loff_t *ppos, int nonblocking) { return __vb2_perform_fileio(q, (char __user *) data, count, ppos, nonblocking, 0); diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index 4b6a9d2ea372..bbdef1f63eab 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -1064,8 +1064,8 @@ __poll_t vb2_core_poll(struct vb2_queue *q, struct file *file, * @ppos: file handle position tracking pointer * @nonblock: mode selector (1 means blocking calls, 0 means nonblocking) */ -size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, - loff_t *ppos, int nonblock); +ssize_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, + loff_t *ppos, int nonblock); /** * vb2_write() - implements write() syscall logic. * @q: pointer to &struct vb2_queue with videobuf2 queue. @@ -1074,8 +1074,8 @@ size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count, * @ppos: file handle position tracking pointer * @nonblock: mode selector (1 means blocking calls, 0 means nonblocking) */ -size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count, - loff_t *ppos, int nonblock); +ssize_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count, + loff_t *ppos, int nonblock); /** * typedef vb2_thread_fnc - callback function for use with vb2_thread.