Return an error, rather than a flag value, from `nvdebug_reg32_read()`

This is used to back APIs like `num_gpcs`. Better to return an error
to the caller, rather than -1 (which may be confused for an actual
result).

1 files changed, 6 insertions, 2 deletions

diff --git a/device_info_procfs.c b/device_info_procfs.c
index ce5843f..0229eec 100644
--- a/device_info_procfs.c
+++ b/device_info_procfs.c
@@ -12,13 +12,17 @@
 static ssize_t nvdebug_reg32_read(struct file *f, char __user *buf, size_t size, loff_t *off) {
         char out[16];
         int chars_written;
+        uint32_t read;
         struct nvdebug_state *g = &g_nvdebug_state[file2parentgpuidx(f)];
         if (size < 16 || *off != 0)
                 return 0;
+
+        if ((read = nvdebug_readl(g, (uintptr_t)pde_data(file_inode(f)))) == -1)
+                return -EOPNOTSUPP;
         // 32 bit register will always take less than 16 characters to print
-        chars_written = scnprintf(out, 16, "%#0x\n", nvdebug_readl(g, (uintptr_t)pde_data(file_inode(f))));
+        chars_written = scnprintf(out, 16, "%#0x\n", nvdebug_readl(g, read));
         if (copy_to_user(buf, out, chars_written))
-                printk(KERN_WARNING "Unable to copy all data for %s\n", file_dentry(f)->d_name.name);
+                printk(KERN_WARNING "[nvdebug] %s: Unable to copy all data for %s\n", __func__, file_dentry(f)->d_name.name);
         *off += chars_written;
         return chars_written;
 }