Implement ->proc_write_buf() so procfs copies in what is written before it pins the entry, and put that copy into the fifo with kfifo_in() instead of kfifo_from_user(). Writes larger than PAGE_SIZE - 1 bytes fail with -EINVAL now. kfifo_from_user() cut a record to 255 bytes, what the one byte that holds its length can say, so the record sample keeps doing that with PROC_ENTRY_SHORT_WRITES.
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 | 12 ++++++------ 3 files changed, 13 insertions(+), 18 deletions(-) diff --git a/samples/kfifo/bytestream-example.c b/samples/kfifo/bytestream-example.c index 4ae29a12cc8a..8c58fb46a2bf 100644 --- a/samples/kfifo/bytestream-example.c +++ b/samples/kfifo/bytestream-example.c @@ -110,20 +110,17 @@ static int __init testfunc(void) return 0; } -static ssize_t fifo_write(struct file *file, const char __user *buf, +static ssize_t fifo_write(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&write_access)) return -ERESTARTSYS; - ret = kfifo_from_user(&test, buf, count, &copied); + copied = kfifo_in(&test, buf, count); mutex_unlock(&write_access); - if (ret) - return ret; return copied; } @@ -148,7 +145,7 @@ static ssize_t fifo_read(struct file *file, char __user *buf, static const struct proc_ops fifo_proc_ops = { .proc_read = fifo_read, - .proc_write = fifo_write, + .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, }; diff --git a/samples/kfifo/inttype-example.c b/samples/kfifo/inttype-example.c index e4f93317c5d0..c5d16b815e73 100644 --- a/samples/kfifo/inttype-example.c +++ b/samples/kfifo/inttype-example.c @@ -103,20 +103,18 @@ static int __init testfunc(void) return 0; } -static ssize_t fifo_write(struct file *file, const char __user *buf, +static ssize_t fifo_write(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&write_access)) return -ERESTARTSYS; - ret = kfifo_from_user(&test, buf, count, &copied); + copied = kfifo_in(&test, (const int *)buf, count / sizeof(int)) * + sizeof(int); mutex_unlock(&write_access); - if (ret) - return ret; return copied; } @@ -141,7 +139,7 @@ static ssize_t fifo_read(struct file *file, char __user *buf, static const struct proc_ops fifo_proc_ops = { .proc_read = fifo_read, - .proc_write = fifo_write, + .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, }; diff --git a/samples/kfifo/record-example.c b/samples/kfifo/record-example.c index e4d1a2d7983c..dcc749247c64 100644 --- a/samples/kfifo/record-example.c +++ b/samples/kfifo/record-example.c @@ -117,20 +117,17 @@ static int __init testfunc(void) return 0; } -static ssize_t fifo_write(struct file *file, const char __user *buf, +static ssize_t fifo_write(struct file *file, char *buf, size_t count, loff_t *ppos) { - int ret; unsigned int copied; if (mutex_lock_interruptible(&write_access)) return -ERESTARTSYS; - ret = kfifo_from_user(&test, buf, count, &copied); + copied = kfifo_in(&test, buf, count); mutex_unlock(&write_access); - if (ret) - return ret; return copied; } @@ -155,8 +152,11 @@ static ssize_t fifo_read(struct file *file, char __user *buf, static const struct proc_ops fifo_proc_ops = { .proc_read = fifo_read, - .proc_write = fifo_write, + .proc_write_buf = fifo_write, .proc_lseek = noop_llseek, + /* kfifo_from_user() cut a record to what its length byte holds */ + .proc_flags = PROC_ENTRY_SHORT_WRITES, + .proc_write_size = U8_MAX, }; static int __init example_init(void) -- 2.53.0
