procfs{2, 3}: Change to use offset parameter

To make sure the behavior of the read and write operations are correct
with offset, update it each time. Also, since it is using the offset,
modify the part of read for removing unnecessary variable.

diff --git a/examples/procfs2.c b/examples/procfs2.c
index bb2aa614a5cbba2129d2be00ae9c626927e74003..896a77703df24f02d71a827e3d6862e230fed51b 100644 (file)
--- a/examples/procfs2.c
+++ b/examples/procfs2.c
@@ -55,6 +55,7 @@ static ssize_t procfile_write(struct file *file, const char __user *buff,
         return -EFAULT;
 
     procfs_buffer[procfs_buffer_size & (PROCFS_MAX_SIZE - 1)] = '\0';
+    *off += procfs_buffer_size;
     pr_info("procfile write %s\n", procfs_buffer);
 
     return procfs_buffer_size;

diff --git a/examples/procfs3.c b/examples/procfs3.c
index bbf40ce41d71e47acb035fa0d3ab7892e4dd0fa0..6d414172fff425140c673ae9fb32cc9f4c59e177 100644 (file)
--- a/examples/procfs3.c
+++ b/examples/procfs3.c
@@ -8,12 +8,13 @@
 #include <linux/sched.h>
 #include <linux/uaccess.h>
 #include <linux/version.h>
+#include <linux/minmax.h>
 
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
 #define HAVE_PROC_OPS
 #endif
 
-#define PROCFS_MAX_SIZE 2048
+#define PROCFS_MAX_SIZE 2048UL
 #define PROCFS_ENTRY_FILENAME "buffer2k"
 
 static struct proc_dir_entry *our_proc_file;
@@ -23,17 +24,15 @@ static unsigned long procfs_buffer_size = 0;
 static ssize_t procfs_read(struct file *filp, char __user *buffer,
                            size_t length, loff_t *offset)
 {
-    static int finished = 0;
-
-    if (finished) {
+    if (*offset || procfs_buffer_size == 0) {
         pr_debug("procfs_read: END\n");
-        finished = 0;
+        *offset = 0;
         return 0;
     }
-    finished = 1;
-
+    procfs_buffer_size = min(procfs_buffer_size, length);
     if (copy_to_user(buffer, procfs_buffer, procfs_buffer_size))
         return -EFAULT;
+    *offset += procfs_buffer_size;
 
     pr_debug("procfs_read: read %lu bytes\n", procfs_buffer_size);
     return procfs_buffer_size;
@@ -41,12 +40,10 @@ static ssize_t procfs_read(struct file *filp, char __user *buffer,
 static ssize_t procfs_write(struct file *file, const char __user *buffer,
                             size_t len, loff_t *off)
 {
-    if (len > PROCFS_MAX_SIZE)
-        procfs_buffer_size = PROCFS_MAX_SIZE;
-    else
-        procfs_buffer_size = len;
+    procfs_buffer_size = min(PROCFS_MAX_SIZE, len);
     if (copy_from_user(procfs_buffer, buffer, procfs_buffer_size))
         return -EFAULT;
+    *off += procfs_buffer_size;
 
     pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size);
     return procfs_buffer_size;