Implement ->proc_read_buf() so procfs copies what is read to userspace after it unpinned the entry, and take the data out of the fifo with kfifo_out() instead of kfifo_to_user(). A reader that passes a bad buffer loses what was taken out for it now, kfifo_to_user() left that in the fifo. The samples can be spliced now too, and a sendfile() from them into a target that fails or takes less than was read drops what was taken out in between, like for the rtas error log.
Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- samples/kfifo/bytestream-example.c | 9 +++------ samples/kfifo/inttype-example.c | 10 ++++------ samples/kfifo/record-example.c | 9 +++------ 3 files changed, 10 insertions(+), 18 deletions(-) diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c index 8c58fb46a2bf..214e46a64cc1 100644 --- a/samples/kfifo/bytestream-example.c +++ b/samples/kfifo/bytestream-example.c @@ -125,26 +125,23 @@ static ssize_t fifo_write(struct file *file, char *buf, return copied; } -static ssize_t fifo_read(struct file *file, char __user *buf, +static ssize_t fifo_read(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&read_access)) return -ERESTARTSYS; - ret = kfifo_to_user(&test, buf, count, &copied); + copied = kfifo_out(&test, buf, count); mutex_unlock(&read_access); - if (ret) - return ret; return copied; } static const struct proc_ops fifo_proc_ops = { - .proc_read = fifo_read, + .proc_read_buf = fifo_read, .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, }; diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c index c5d16b815e73..8384d7f8de6c 100644 --- a/samples/kfifo/inttype-example.c +++ b/samples/kfifo/inttype-example.c @@ -119,26 +119,24 @@ static ssize_t fifo_write(struct file *file, char *buf, return copied; } -static ssize_t fifo_read(struct file *file, char __user *buf, +static ssize_t fifo_read(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&read_access)) return -ERESTARTSYS; - ret = kfifo_to_user(&test, buf, count, &copied); + copied = kfifo_out(&test, (int *)buf, count / sizeof(int)) * + sizeof(int); mutex_unlock(&read_access); - if (ret) - return ret; return copied; } static const struct proc_ops fifo_proc_ops = { - .proc_read = fifo_read, + .proc_read_buf = fifo_read, .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, }; diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c index dcc749247c64..29d08e90a63d 100644 --- a/samples/kfifo/record-example.c +++ b/samples/kfifo/record-example.c @@ -132,26 +132,23 @@ static ssize_t fifo_write(struct file *file, char *buf, return copied; } -static ssize_t fifo_read(struct file *file, char __user *buf, +static ssize_t fifo_read(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&read_access)) return -ERESTARTSYS; - ret = kfifo_to_user(&test, buf, count, &copied); + copied = kfifo_out(&test, buf, count); mutex_unlock(&read_access); - if (ret) - return ret; return copied; } static const struct proc_ops fifo_proc_ops = { - .proc_read = fifo_read, + .proc_read_buf = fifo_read, .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, /* kfifo_from_user() cut a record to what its length byte holds */ -- 2.53.0
