[src/trunk]: src/sys/dev/gpio gpio(4) keeps track of child devices attached u...

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

details:   https://anonhg.NetBSD.org/src/rev/e3ad9f944683
branches:  trunk
changeset: 769086:e3ad9f944683
user:      mbalmer <mbalmer%NetBSD.org@localhost>
date:      Wed Aug 31 12:07:26 2011 +0000

description:
gpio(4) keeps track of child devices attached using the GPIOATTACH ioctl(),
so remove those references and free the memory in gpio_childdetached().
Protect access to the list of child devices with a kcondvar.

diffstat:

 sys/dev/gpio/gpio.c |  97 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 84 insertions(+), 13 deletions(-)

diffs (167 lines):

diff -r 843a6b1abb1a -r e3ad9f944683 sys/dev/gpio/gpio.c
--- a/sys/dev/gpio/gpio.c       Wed Aug 31 10:01:18 2011 +0000
+++ b/sys/dev/gpio/gpio.c       Wed Aug 31 12:07:26 2011 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: gpio.c,v 1.38 2011/08/30 07:22:11 mbalmer Exp $ */
+/* $NetBSD: gpio.c,v 1.39 2011/08/31 12:07:26 mbalmer Exp $ */
 /*     $OpenBSD: gpio.c,v 1.6 2006/01/14 12:33:49 grange Exp $ */
 
 /*
@@ -19,7 +19,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gpio.c,v 1.38 2011/08/30 07:22:11 mbalmer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gpio.c,v 1.39 2011/08/31 12:07:26 mbalmer Exp $");
 
 /*
  * General Purpose Input/Output framework.
@@ -63,6 +63,8 @@
        kmutex_t                 sc_mtx;
        kcondvar_t               sc_ioctl;      /* ioctl in progress */
        int                      sc_ioctl_busy; /* ioctl is busy */
+       kcondvar_t               sc_attach;     /* attach/detach in progress */
+       int                      sc_attach_busy;/* busy in attach/detach */
        LIST_HEAD(, gpio_dev)    sc_devs;       /* devices */
        LIST_HEAD(, gpio_name)   sc_names;      /* named pins */
 };
@@ -134,7 +136,40 @@
 static void
 gpio_childdetached(device_t self, device_t child)
 {
-       /* gpio(4) keeps no references to its children, so do nothing. */
+       struct gpio_dev *gdev;
+       struct gpio_softc *sc;
+       int error;
+
+       /*
+        * gpio_childetached is serialized because it can be entered in
+        * different ways concurrently, e.g. via the GPIODETACH ioctl and
+        * drvctl(8) or modunload(8).
+        */
+       sc = device_private(self);
+       error = 0;
+       mutex_enter(&sc->sc_mtx);
+       while (sc->sc_attach_busy) {
+               error = cv_wait_sig(&sc->sc_attach, &sc->sc_mtx);
+               if (error)
+                       break;
+       }
+       if (!error)
+               sc->sc_attach_busy = 1;
+       mutex_exit(&sc->sc_mtx);
+       if (error)
+               return;
+
+       LIST_FOREACH(gdev, &sc->sc_devs, sc_next)
+               if (gdev->sc_dev == child) {
+                       LIST_REMOVE(gdev, sc_next);
+                       kmem_free(gdev, sizeof(struct gpio_dev));
+                       break;
+               }
+
+       mutex_enter(&sc->sc_mtx);
+       sc->sc_attach_busy = 0;
+       cv_signal(&sc->sc_attach);
+       mutex_exit(&sc->sc_mtx);
 }
 
 static int
@@ -169,7 +204,7 @@
                aprint_error_dev(self, "couldn't establish power handler\n");
        mutex_init(&sc->sc_mtx, MUTEX_DEFAULT, IPL_VM);
        cv_init(&sc->sc_ioctl, "gpioctl");
-
+       cv_init(&sc->sc_attach, "gpioatch");
        /*
         * Attach all devices that can be connected to the GPIO pins
         * described in the kernel configuration file.
@@ -478,7 +513,7 @@
        cfdata_t cf;
        kauth_cred_t cred;
        int locs[GPIOCF_NLOCS];
-       int pin, value, flags, npins;
+       int error, pin, value, flags, npins;
 
        gc = sc->sc_gc;
 
@@ -642,6 +677,19 @@
                if (!gpio_pin_can_map(sc, attach->ga_offset, attach->ga_mask))
                        return EBUSY;
 
+               error = 0;
+               mutex_enter(&sc->sc_mtx);
+               while (sc->sc_attach_busy) {
+                       error = cv_wait_sig(&sc->sc_attach, &sc->sc_mtx);
+                       if (error)
+                               break;
+               }
+               if (!error)
+                       sc->sc_attach_busy = 1;
+               mutex_exit(&sc->sc_mtx);
+               if (error)
+                       return EBUSY;
+
                ga.ga_gpio = sc;
                ga.ga_dvname = attach->ga_dvname;
                ga.ga_offset = attach->ga_offset;
@@ -664,28 +712,51 @@
                                gdev->sc_dev = dv;
                                LIST_INSERT_HEAD(&sc->sc_devs, gdev, sc_next);
                        } else
-                               return EINVAL;
+                               error = EINVAL;
                } else
-                       return EINVAL;
-               return 0;
+                       error = EINVAL;
+               mutex_enter(&sc->sc_mtx);
+               sc->sc_attach_busy = 0;
+               cv_signal(&sc->sc_attach);
+               mutex_exit(&sc->sc_mtx);
+               return error;
        case GPIODETACH:
                if (kauth_authorize_device(cred, KAUTH_DEVICE_GPIO_PINSET,
                    NULL, NULL, NULL, NULL))
                        return EPERM;
 
+               mutex_enter(&sc->sc_mtx);
+               while (sc->sc_attach_busy) {
+                       error = cv_wait_sig(&sc->sc_attach, &sc->sc_mtx);
+                       if (error)
+                               break;
+               }
+               if (!error)
+                       sc->sc_attach_busy = 1;
+               mutex_exit(&sc->sc_mtx);
+               if (error)
+                       return EBUSY;
+
                attach = (struct gpio_attach *)data;
                LIST_FOREACH(gdev, &sc->sc_devs, sc_next) {
                        if (strcmp(device_xname(gdev->sc_dev),
                            attach->ga_dvname) == 0) {
-                               if (config_detach(gdev->sc_dev, 0) == 0) {
-                                       LIST_REMOVE(gdev, sc_next);
-                                       kmem_free(gdev,
-                                           sizeof(struct gpio_dev));
+                               mutex_enter(&sc->sc_mtx);
+                               sc->sc_attach_busy = 0;
+                               cv_signal(&sc->sc_attach);
+                               mutex_exit(&sc->sc_mtx);
+
+                               if (config_detach(gdev->sc_dev, 0) == 0)
                                        return 0;
-                               }
                                break;
                        }
                }
+               if (gdev == NULL) {
+                       mutex_enter(&sc->sc_mtx);
+                       sc->sc_attach_busy = 0;
+                       cv_signal(&sc->sc_attach);
+                       mutex_exit(&sc->sc_mtx);
+               }
                return EINVAL;
        case GPIOSET:
                if (kauth_authorize_device(cred, KAUTH_DEVICE_GPIO_PINSET,