@@ -1642,16 +1642,15 @@ static ssize_t linereq_read(struct file *file, char __user *buf,
return ret;
}
- ret = kfifo_out(&lr->events, &le, 1);
- }
- if (ret != 1) {
- /*
- * This should never happen - we were holding the
- * lock from the moment we learned the fifo is no
- * longer empty until now.
- */
- ret = -EIO;
- break;
+ if (kfifo_out(&lr->events, &le, 1) != 1) {
+ /*
+ * This should never happen - we hold the
+ * lock from the moment we learned the fifo
+ * is no longer empty until now.
+ */
+ WARN(1, "failed to read from non-empty kfifo");
+ return -EIO;
+ }
}
if (copy_to_user(buf + bytes_read, &le, sizeof(le)))
@@ -1995,16 +1994,15 @@ static ssize_t lineevent_read(struct file *file, char __user *buf,
return ret;
}
- ret = kfifo_out(&le->events, &ge, 1);
- }
- if (ret != 1) {
- /*
- * This should never happen - we were holding the lock
- * from the moment we learned the fifo is no longer
- * empty until now.
- */
- ret = -EIO;
- break;
+ if (kfifo_out(&le->events, &ge, 1) != 1) {
+ /*
+ * This should never happen - we hold the
+ * lock from the moment we learned the fifo
+ * is no longer empty until now.
+ */
+ WARN(1, "failed to read from non-empty kfifo");
+ return -EIO;
+ }
}
if (copy_to_user(buf + bytes_read, &ge, ge_size))
@@ -2707,12 +2705,15 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
if (count < event_size)
return -EINVAL;
#endif
- ret = kfifo_out(&cdev->events, &event, 1);
- }
- if (ret != 1) {
- ret = -EIO;
- break;
- /* We should never get here. See lineevent_read(). */
+ if (kfifo_out(&cdev->events, &event, 1) != 1) {
+ /*
+ * This should never happen - we hold the
+ * lock from the moment we learned the fifo
+ * is no longer empty until now.
+ */
+ WARN(1, "failed to read from non-empty kfifo");
+ return -EIO;
+ }
}
#ifdef CONFIG_GPIO_CDEV_V1
The handling of kfifo_out() errors in read functions obscures any error. The error condition should never occur but, while a ret is set to -EIO, it is subsequently ignored and the read functions instead return the number of bytes copied to that point, potentially masking the fact that any error occurred. Log a warning and return -EIO in the case of a kfifo_out() error to make it clear something very odd is going on here. Signed-off-by: Kent Gibson <warthog618@gmail.com> --- drivers/gpio/gpiolib-cdev.c | 53 +++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 26 deletions(-) -- 2.39.2