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authorAl Viro <viro@zeniv.linux.org.uk>2018-09-14 05:12:15 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2018-10-13 07:50:53 +0300
commitf0193d3ea73b966b5dbfa272c8228d743b8856ef (patch)
treec882a171c8706f274a7e09d8f7297c36ed750e34 /include/linux/tty_ldisc.h
parent7ee329655189f32f0c17e0bad60c23a69b003e9e (diff)
downloadlinux-f0193d3ea73b966b5dbfa272c8228d743b8856ef.tar.xz
change semantics of ldisc ->compat_ioctl()
First of all, make it return int. Returning long when native method had never allowed that is ridiculous and inconvenient. More importantly, change the caller; if ldisc ->compat_ioctl() is NULL or returns -ENOIOCTLCMD, tty_compat_ioctl() will try to feed cmd and compat_ptr(arg) to ldisc's native ->ioctl(). That simplifies ->compat_ioctl() instances quite a bit - they only need to deal with ioctls that are neither generic tty ones (those would get shunted off to tty_ioctl()) nor simple compat pointer ones. Note that something like TCFLSH won't reach ->compat_ioctl(), even if ldisc ->ioctl() does handle it - it will be recognized earlier and passed to tty_ioctl() (and ultimately - ldisc ->ioctl()). For many ldiscs it means that NULL ->compat_ioctl() does the right thing. Those where it won't serve (see e.g. n_r3964.c) are also easily dealt with - we need to handle the numeric-argument ioctls (calling the native instance) and, if such would exist, the ioctls that need layout conversion, etc. All in-tree ldiscs dealt with. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/tty_ldisc.h')
-rw-r--r--include/linux/tty_ldisc.h10
1 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/tty_ldisc.h b/include/linux/tty_ldisc.h
index 840894ca3fc0..b1e6043e9917 100644
--- a/include/linux/tty_ldisc.h
+++ b/include/linux/tty_ldisc.h
@@ -54,11 +54,17 @@
* low-level driver can "grab" an ioctl request before the line
* discpline has a chance to see it.
*
- * long (*compat_ioctl)(struct tty_struct * tty, struct file * file,
+ * int (*compat_ioctl)(struct tty_struct * tty, struct file * file,
* unsigned int cmd, unsigned long arg);
*
* Process ioctl calls from 32-bit process on 64-bit system
*
+ * NOTE: only ioctls that are neither "pointer to compatible
+ * structure" nor tty-generic. Something private that takes
+ * an integer or a pointer to wordsize-sensitive structure
+ * belongs here, but most of ldiscs will happily leave
+ * it NULL.
+ *
* void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
*
* This function notifies the line discpline that a change has
@@ -184,7 +190,7 @@ struct tty_ldisc_ops {
const unsigned char *buf, size_t nr);
int (*ioctl)(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg);
- long (*compat_ioctl)(struct tty_struct *tty, struct file *file,
+ int (*compat_ioctl)(struct tty_struct *tty, struct file *file,
unsigned int cmd, unsigned long arg);
void (*set_termios)(struct tty_struct *tty, struct ktermios *old);
__poll_t (*poll)(struct tty_struct *, struct file *,