mirror of
https://github.com/nelsbrock/fun-linux-patches.git
synced 2026-08-14 13:52:09 +02:00
97 lines
2.9 KiB
Diff
97 lines
2.9 KiB
Diff
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
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index 3c6670cf905f..ec176debb778 100644
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--- a/drivers/char/mem.c
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+++ b/drivers/char/mem.c
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@@ -30,6 +30,8 @@
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#include <linux/uio.h>
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#include <linux/uaccess.h>
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#include <linux/security.h>
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+#include <linux/minmax.h>
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+#include <linux/printk.h>
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#define DEVMEM_MINOR 1
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#define DEVPORT_MINOR 4
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@@ -428,7 +430,20 @@ static ssize_t write_port(struct file *file, const char __user *buf,
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static ssize_t read_null(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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- return 0;
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+ static const char content[] = "null\n";
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+ size_t content_length = sizeof(content);
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+
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+ if (*ppos >= content_length)
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+ return 0;
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+
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+ size_t copy_len = min(content_length - *ppos, count);
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+ if (copy_to_user(buf, content + *ppos, copy_len)) {
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+ pr_err("null: User copy failed\n");
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+ return -EFAULT;
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+ }
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+
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+ *ppos += copy_len;
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+ return copy_len;
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}
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static ssize_t write_null(struct file *file, const char __user *buf,
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@@ -437,33 +452,23 @@ static ssize_t write_null(struct file *file, const char __user *buf,
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return count;
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}
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-static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to)
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-{
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- return 0;
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-}
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-
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-static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from)
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+static ssize_t write_iter_zero(struct kiocb *iocb, struct iov_iter *from)
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{
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size_t count = iov_iter_count(from);
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iov_iter_advance(from, count);
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return count;
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}
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-static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
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+static int pipe_to_zero(struct pipe_inode_info *info, struct pipe_buffer *buf,
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struct splice_desc *sd)
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{
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return sd->len;
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}
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-static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
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+static ssize_t splice_write_zero(struct pipe_inode_info *pipe, struct file *out,
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loff_t *ppos, size_t len, unsigned int flags)
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{
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- return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
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-}
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-
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-static int uring_cmd_null(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
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-{
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- return 0;
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+ return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_zero);
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}
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static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
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@@ -627,8 +632,6 @@ static int open_port(struct inode *inode, struct file *filp)
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#define zero_lseek null_lseek
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#define full_lseek null_lseek
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#define write_zero write_null
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-#define write_iter_zero write_iter_null
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-#define splice_write_zero splice_write_null
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#define open_mem open_port
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static const struct file_operations __maybe_unused mem_fops = {
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@@ -644,13 +647,8 @@ static const struct file_operations __maybe_unused mem_fops = {
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};
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static const struct file_operations null_fops = {
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- .llseek = null_lseek,
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.read = read_null,
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.write = write_null,
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- .read_iter = read_iter_null,
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- .write_iter = write_iter_null,
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- .splice_write = splice_write_null,
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- .uring_cmd = uring_cmd_null,
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};
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static const struct file_operations __maybe_unused port_fops = {
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