[src/trunk]: src/sys/dev/usb fix uchcom(4) detach, like umodem(4) recently:

[mrg <mrg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/ab3af9affc14
branches:  trunk
changeset: 456207:ab3af9affc14
user:      mrg <mrg%NetBSD.org@localhost>
date:      Sat Apr 27 01:23:26 2019 +0000

description:
fix uchcom(4) detach, like umodem(4) recently:

- use static normally in umodem_common.c
- add sc_refcnt, sc_lock and sc_detach_cv to softc.  usage is:
  - sc_dying is protected by sc_lock
  - sc_detach_cv is matched with sc_lock for cv operations
  - sc_refcnt is increased in open and decreased in close, any time
    it is decreased, it is checked for less than zero, and a broadcast
    performed on sc_detach_cv.  detach waits for sc_refcnt
- uchcom_param() and uchcom_set() check for sc_dying

this fixes pullout out an open ucom@uchcom.

XXX: pullup

diffstat:

 sys/dev/usb/uchcom.c |  107 ++++++++++++++++++++++++++++++++++++--------------
 1 files changed, 76 insertions(+), 31 deletions(-)

diffs (255 lines):

diff -r c52d82c49736 -r ab3af9affc14 sys/dev/usb/uchcom.c
--- a/sys/dev/usb/uchcom.c      Sat Apr 27 00:56:19 2019 +0000
+++ b/sys/dev/usb/uchcom.c      Sat Apr 27 01:23:26 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: uchcom.c,v 1.28 2019/01/31 18:21:21 jakllsch Exp $     */
+/*     $NetBSD: uchcom.c,v 1.29 2019/04/27 01:23:26 mrg Exp $  */
 
 /*
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uchcom.c,v 1.28 2019/01/31 18:21:21 jakllsch Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uchcom.c,v 1.29 2019/04/27 01:23:26 mrg Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_usb.h"
@@ -127,7 +127,10 @@
        struct usbd_device *    sc_udev;
        device_t                sc_subdev;
        struct usbd_interface * sc_iface;
-       int                     sc_dying;
+       bool                    sc_dying;
+       kmutex_t                sc_lock;
+       kcondvar_t              sc_detach_cv;
+       int                     sc_refcnt;
        /* */
        int                     sc_intr_endpoint;
        int                     sc_intr_size;
@@ -170,12 +173,12 @@
 };
 #define uchcom_lookup(v, p)    usb_lookup(uchcom_devs, v, p)
 
-Static void    uchcom_get_status(void *, int, u_char *, u_char *);
-Static void    uchcom_set(void *, int, int, int);
-Static int     uchcom_param(void *, int, struct termios *);
-Static int     uchcom_open(void *, int);
-Static void    uchcom_close(void *, int);
-Static void    uchcom_intr(struct usbd_xfer *, void *,
+static void    uchcom_get_status(void *, int, u_char *, u_char *);
+static void    uchcom_set(void *, int, int, int);
+static int     uchcom_param(void *, int, struct termios *);
+static int     uchcom_open(void *, int);
+static void    uchcom_close(void *, int);
+static void    uchcom_intr(struct usbd_xfer *, void *,
                            usbd_status);
 
 static int     set_config(struct uchcom_softc *);
@@ -245,10 +248,14 @@
 
        sc->sc_dev = self;
         sc->sc_udev = dev;
-       sc->sc_dying = 0;
+       sc->sc_dying = false;
+       sc->sc_refcnt = 0;
        sc->sc_dtr = sc->sc_rts = -1;
        sc->sc_lsr = sc->sc_msr = 0;
 
+       mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_SOFTUSB);
+       cv_init(&sc->sc_detach_cv, "uchcomdet");
+
        DPRINTF(("\n\nuchcom attach: sc=%p\n", sc));
 
        if (set_config(sc))
@@ -285,7 +292,9 @@
        return;
 
 failed:
-       sc->sc_dying = 1;
+       mutex_enter(&sc->sc_lock);
+       sc->sc_dying = true;
+       mutex_exit(&sc->sc_lock);
        return;
 }
 
@@ -308,13 +317,24 @@
 
        close_intr_pipe(sc);
 
-       sc->sc_dying = 1;
+       mutex_enter(&sc->sc_lock);
+       sc->sc_dying = true;
+
+       sc->sc_refcnt--;
+       while (sc->sc_refcnt > 0) {
+               if (cv_timedwait(&sc->sc_detach_cv, &sc->sc_lock, hz * 60))
+                       aprint_error_dev(sc->sc_dev, ": didn't detach\n");
+       }
+       mutex_exit(&sc->sc_lock);
 
        if (sc->sc_subdev != NULL)
                rv = config_detach(sc->sc_subdev, flags);
 
        usbd_add_drv_event(USB_EVENT_DRIVER_DETACH, sc->sc_udev, sc->sc_dev);
 
+       mutex_destroy(&sc->sc_lock);
+       cv_destroy(&sc->sc_detach_cv);
+
        return rv;
 }
 
@@ -326,7 +346,9 @@
        switch (act) {
        case DVACT_DEACTIVATE:
                close_intr_pipe(sc);
-               sc->sc_dying = 1;
+               mutex_enter(&sc->sc_lock);
+               sc->sc_dying = true;
+               mutex_exit(&sc->sc_lock);
                return 0;
        default:
                return EOPNOTSUPP;
@@ -850,8 +872,10 @@
 {
        usbd_status err;
 
+       mutex_enter(&sc->sc_lock);
        if (sc->sc_dying)
                return;
+       mutex_exit(&sc->sc_lock);
 
        if (sc->sc_intr_pipe != NULL) {
                err = usbd_abort_pipe(sc->sc_intr_pipe);
@@ -873,25 +897,29 @@
 /* ----------------------------------------------------------------------
  * methods for ucom
  */
-void
+static void
 uchcom_get_status(void *arg, int portno, u_char *rlsr, u_char *rmsr)
 {
        struct uchcom_softc *sc = arg;
 
+       mutex_enter(&sc->sc_lock);
        if (sc->sc_dying)
                return;
+       mutex_exit(&sc->sc_lock);
 
        *rlsr = sc->sc_lsr;
        *rmsr = sc->sc_msr;
 }
 
-void
+static void
 uchcom_set(void *arg, int portno, int reg, int onoff)
 {
        struct uchcom_softc *sc = arg;
 
+       mutex_enter(&sc->sc_lock);
        if (sc->sc_dying)
                return;
+       mutex_exit(&sc->sc_lock);
 
        switch (reg) {
        case UCOM_SET_DTR:
@@ -908,14 +936,16 @@
        }
 }
 
-int
+static int
 uchcom_param(void *arg, int portno, struct termios *t)
 {
        struct uchcom_softc *sc = arg;
        int ret;
 
+       mutex_enter(&sc->sc_lock);
        if (sc->sc_dying)
                return 0;
+       mutex_exit(&sc->sc_lock);
 
        ret = set_line_control(sc, t->c_cflag);
        if (ret)
@@ -928,50 +958,65 @@
        return 0;
 }
 
-int
+static int
 uchcom_open(void *arg, int portno)
 {
        int ret;
        struct uchcom_softc *sc = arg;
 
-       if (sc->sc_dying)
+       mutex_enter(&sc->sc_lock);
+       if (sc->sc_dying) {
+               mutex_exit(&sc->sc_lock);
                return EIO;
+       }
+
+       sc->sc_refcnt++;
+       mutex_exit(&sc->sc_lock);
 
        ret = setup_intr_pipe(sc);
-       if (ret)
-               return ret;
+       if (ret == 0)
+               ret = setup_comm(sc);
 
-       ret = setup_comm(sc);
-       if (ret)
-               return ret;
-
-       return 0;
+       if (ret) {
+               mutex_enter(&sc->sc_lock);
+               if (--sc->sc_refcnt < 0)
+                       cv_broadcast(&sc->sc_detach_cv);
+               mutex_exit(&sc->sc_lock);
+       }
+       return ret;
 }
 
-void
+static void
 uchcom_close(void *arg, int portno)
 {
        struct uchcom_softc *sc = arg;
 
-       if (sc->sc_dying)
-               return;
-
-       close_intr_pipe(sc);
+       mutex_enter(&sc->sc_lock);
+       if (!sc->sc_dying) {
+               mutex_exit(&sc->sc_lock);
+               close_intr_pipe(sc);
+               mutex_enter(&sc->sc_lock);
+       }
+       if (--sc->sc_refcnt < 0)
+               cv_broadcast(&sc->sc_detach_cv);
+       mutex_exit(&sc->sc_lock);
 }
 
 
 /* ----------------------------------------------------------------------
  * callback when the modem status is changed.
  */
-void
+static void
 uchcom_intr(struct usbd_xfer *xfer, void * priv,
            usbd_status status)
 {
        struct uchcom_softc *sc = priv;
        u_char *buf = sc->sc_intr_buf;
 
+       mutex_enter(&sc->sc_lock);
        if (sc->sc_dying)
                return;
+       mutex_exit(&sc->sc_lock);
 
        if (status != USBD_NORMAL_COMPLETION) {
                if (status == USBD_NOT_STARTED || status == USBD_CANCELLED)