[src/pgoyette-localcount]: src/sys Initial set of changes for subr_autoconf u...

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

details:   https://anonhg.NetBSD.org/src/rev/8f9255296e48
branches:  pgoyette-localcount
changeset: 852786:8f9255296e48
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Sat Jul 16 02:13:07 2016 +0000

description:
Initial set of changes for subr_autoconf usage of localcount mechanism.

Nothing actually uses this yet - all callers of device_lookup() need
conversion to device_lookup_acquire()/device_release().  This also
means that callers of device_lookup_private() need to be modified to
call device_release() when finished accessing the softc.

XXX Perhaps device_lookup_private() should be removed, and all callers
XXX modified to use device_lookup_acquire()/.../device_release()?

diffstat:

 sys/kern/subr_autoconf.c |  57 +++++++++++++++++++++++++++++++++++++++++------
 sys/sys/device.h         |   5 +++-
 2 files changed, 53 insertions(+), 9 deletions(-)

diffs (181 lines):

diff -r 0d5a69f8b3a2 -r 8f9255296e48 sys/kern/subr_autoconf.c
--- a/sys/kern/subr_autoconf.c  Fri Jul 15 02:29:19 2016 +0000
+++ b/sys/kern/subr_autoconf.c  Sat Jul 16 02:13:07 2016 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_autoconf.c,v 1.246 2016/07/15 01:17:47 pgoyette Exp $ */
+/* $NetBSD: subr_autoconf.c,v 1.246.2.1 2016/07/16 02:13:07 pgoyette Exp $ */
 
 /*
  * Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.246 2016/07/15 01:17:47 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.246.2.1 2016/07/16 02:13:07 pgoyette Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -107,6 +107,7 @@
 #include <sys/devmon.h>
 #include <sys/cpu.h>
 #include <sys/sysctl.h>
+#include <sys/localcount.h>
 
 #include <sys/disk.h>
 
@@ -227,6 +228,7 @@
 static int config_pending;             /* semaphore for mountroot */
 static kmutex_t config_misc_lock;
 static kcondvar_t config_misc_cv;
+static kcondvar_t config_drain_cv;
 
 static bool detachall = false;
 
@@ -345,6 +347,7 @@
 
        mutex_init(&config_misc_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&config_misc_cv, "cfgmisc");
+       cv_init(&config_drain_cv, "cfgdrain");
 
        callout_init(&config_twiddle_ch, CALLOUT_MPSAFE);
 
@@ -567,7 +570,6 @@
                if (STREQ(lcd->cd_name, cd->cd_name))
                        return EEXIST;
        }
-
        LIST_INIT(&cd->cd_attach);
        LIST_INSERT_HEAD(&allcfdrivers, cd, cd_list);
 
@@ -592,7 +594,6 @@
                }
        }
        config_alldevs_exit(&af);
-
        if (rc != 0)
                return rc;
 
@@ -1236,6 +1237,8 @@
 {
        int priv = (dev->dv_flags & DVF_PRIV_ALLOC);
 
+       if (dev->dv_localcnt != NULL)
+               localcount_fini(dev->dv_localcnt);
        if (dev->dv_cfattach->ca_devsize > 0)
                kmem_free(dev->dv_private, dev->dv_cfattach->ca_devsize);
        if (priv)
@@ -1254,6 +1257,9 @@
 
        KASSERT(mutex_owned(&alldevs_mtx));
 
+       localcount_drain(dev->dv_localcnt, &config_drain_cv,
+           &alldevs_mtx);
+
        /* Unlink from device list.  Link to garbage list. */
        TAILQ_REMOVE(&alldevs, dev, dv_list);
        TAILQ_INSERT_TAIL(garbage, dev, dv_list);
@@ -1392,8 +1398,8 @@
                printf("%s has not been converted to device_t\n", cd->cd_name);
 #endif
        }
-       if (dev == NULL)
-               panic("config_devalloc: memory allocation for device_t failed");
+       KASSERTMSG(dev, "%s: memory allocation for %s device_t failed",
+           __func__, cd->cd_name);
 
        dev->dv_class = cd->cd_class;
        dev->dv_cfdata = cf;
@@ -1403,6 +1409,10 @@
        dev->dv_activity_handlers = NULL;
        dev->dv_private = dev_private;
        dev->dv_flags = ca->ca_flags;   /* inherit flags from class */
+       dev->dv_localcnt = kmem_alloc(sizeof(*dev->dv_localcnt), KM_SLEEP);
+       KASSERTMSG(dev->dv_localcnt, "%s: unable to allocate localcnt for %s",
+           __func__, cd->cd_name);
+       localcount_init(dev->dv_localcnt);
 
        myunit = config_unit_alloc(dev, cd, cf);
        if (myunit == -1) {
@@ -2245,6 +2255,37 @@
 }
 
 /*
+ * device_lookup_accquire:
+ *
+ *     Look up a device instance for a given driver and
+ *     hold a reference to the device.
+ */
+device_t
+device_lookup_acquire(cfdriver_t cd, int unit)
+{
+       device_t dv;
+
+       dv = device_lookup(cd, unit);
+       if (dv != NULL)
+               localcount_acquire(dv->dv_localcnt);
+       return dv;
+}
+
+/*
+ * device_release:
+ *
+ *     Release the reference that was created by an earlier call to
+ *     device_lookup_acquire().
+ */
+void
+device_release(device_t dv)
+{
+
+       localcount_release(dv->dv_localcnt, &config_drain_cv,
+           &alldevs_mtx);
+}
+
+/*
  * device_lookup_private:
  *
  *     Look up a softc instance for a given driver.
@@ -2253,7 +2294,7 @@
 device_lookup_private(cfdriver_t cd, int unit)
 {
 
-       return device_private(device_lookup(cd, unit));
+       return device_private(device_lookup_acquire(cd, unit));
 }
 
 /*
@@ -2289,7 +2330,7 @@
 
        if ((cd = config_cfdriver_lookup(name)) == NULL)
                return NULL;
-       return device_lookup(cd, unit);
+       return device_lookup_acquire(cd, unit);
 }
 
 /*
diff -r 0d5a69f8b3a2 -r 8f9255296e48 sys/sys/device.h
--- a/sys/sys/device.h  Fri Jul 15 02:29:19 2016 +0000
+++ b/sys/sys/device.h  Sat Jul 16 02:13:07 2016 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: device.h,v 1.149 2016/06/19 09:35:06 bouyer Exp $ */
+/* $NetBSD: device.h,v 1.149.2.1 2016/07/16 02:13:08 pgoyette Exp $ */
 
 /*
  * Copyright (c) 1996, 2000 Christopher G. Demetriou
@@ -188,6 +188,7 @@
            *dv_driver_suspensors[DEVICE_SUSPENSORS_MAX],
            *dv_class_suspensors[DEVICE_SUSPENSORS_MAX];
        struct device_garbage dv_garbage;
+       struct localcount *dv_localcnt; /* reference counter */
 };
 
 /* dv_flags */
@@ -489,6 +490,8 @@
 void   null_childdetached(device_t, device_t);
 
 device_t       device_lookup(cfdriver_t, int);
+device_t       device_lookup_acquire(cfdriver_t, int);
+void           device_release(device_t);
 void           *device_lookup_private(cfdriver_t, int);
 void           device_register(device_t, void *);
 void           device_register_post_config(device_t, void *);