common/dtrace/lockstat.c

	lockstat.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/open.h>
#include <sys/file.h>
#include <sys/conf.h>
#include <sys/modctl.h>
#include <sys/cmn_err.h>
#include <sys/bitmap.h>
#include <sys/debug.h>
#include <sys/kmem.h>
#include <sys/errno.h>
#include <sys/sysmacros.h>
#include <sys/lockstat.h>
#include <sys/atomic.h>
#include <sys/dtrace.h>

#include <sys/ddi.h>
#include <sys/sunddi.h>

typedef struct lockstat_probe {
    const char  *lsp_func;
    const char  *lsp_name;
    int     lsp_probe;
    dtrace_id_t lsp_id;
} lockstat_probe_t;

lockstat_probe_t lockstat_probes[] =
{
    { LS_MUTEX_ENTER,   LSA_ACQUIRE,    LS_MUTEX_ENTER_ACQUIRE },
    { LS_MUTEX_ENTER,   LSA_BLOCK,  LS_MUTEX_ENTER_BLOCK },
    { LS_MUTEX_ENTER,   LSA_SPIN,   LS_MUTEX_ENTER_SPIN },
    { LS_MUTEX_EXIT,    LSA_RELEASE,    LS_MUTEX_EXIT_RELEASE },
    { LS_MUTEX_DESTROY, LSA_RELEASE,    LS_MUTEX_DESTROY_RELEASE },
    { LS_MUTEX_TRYENTER,    LSA_ACQUIRE,    LS_MUTEX_TRYENTER_ACQUIRE },
    { LS_LOCK_SET,      LSS_ACQUIRE,    LS_LOCK_SET_ACQUIRE },
    { LS_LOCK_SET,      LSS_SPIN,   LS_LOCK_SET_SPIN },
    { LS_LOCK_SET_SPL,  LSS_ACQUIRE,    LS_LOCK_SET_SPL_ACQUIRE },
    { LS_LOCK_SET_SPL,  LSS_SPIN,   LS_LOCK_SET_SPL_SPIN },
    { LS_LOCK_TRY,      LSS_ACQUIRE,    LS_LOCK_TRY_ACQUIRE },
    { LS_LOCK_CLEAR,    LSS_RELEASE,    LS_LOCK_CLEAR_RELEASE },
    { LS_LOCK_CLEAR_SPLX,   LSS_RELEASE,    LS_LOCK_CLEAR_SPLX_RELEASE },
    { LS_CLOCK_UNLOCK,  LSS_RELEASE,    LS_CLOCK_UNLOCK_RELEASE },
    { LS_RW_ENTER,      LSR_ACQUIRE,    LS_RW_ENTER_ACQUIRE },
    { LS_RW_ENTER,      LSR_BLOCK,  LS_RW_ENTER_BLOCK },
    { LS_RW_EXIT,       LSR_RELEASE,    LS_RW_EXIT_RELEASE },
    { LS_RW_TRYENTER,   LSR_ACQUIRE,    LS_RW_TRYENTER_ACQUIRE },
    { LS_RW_TRYUPGRADE, LSR_UPGRADE,    LS_RW_TRYUPGRADE_UPGRADE },
    { LS_RW_DOWNGRADE,  LSR_DOWNGRADE,  LS_RW_DOWNGRADE_DOWNGRADE },
    { LS_THREAD_LOCK,   LST_SPIN,   LS_THREAD_LOCK_SPIN },
    { LS_THREAD_LOCK_HIGH,  LST_SPIN,   LS_THREAD_LOCK_HIGH_SPIN },
    { NULL }
};

static dev_info_t   *lockstat_devi; /* saved in xxattach() for xxinfo() */
static kmutex_t     lockstat_test;  /* for testing purposes only */
static dtrace_provider_id_t lockstat_id;

/*ARGSUSED*/
static void
lockstat_enable(void *arg, dtrace_id_t id, void *parg)
{
    lockstat_probe_t *probe = parg;

    ASSERT(!lockstat_probemap[probe->lsp_probe]);

    lockstat_probemap[probe->lsp_probe] = id;
    membar_producer();

    lockstat_probe = dtrace_probe;
    membar_producer();

    lockstat_hot_patch();
    membar_producer();

    /*
     * Immediately generate a record for the lockstat_test mutex
     * to verify that the mutex hot-patch code worked as expected.
     */
    mutex_enter(&lockstat_test);
    mutex_exit(&lockstat_test);
}

/*ARGSUSED*/
static void
lockstat_disable(void *arg, dtrace_id_t id, void *parg)
{
    lockstat_probe_t *probe = parg;
    int i;

    ASSERT(lockstat_probemap[probe->lsp_probe]);

    lockstat_probemap[probe->lsp_probe] = 0;
    lockstat_hot_patch();
    membar_producer();

    /*
     * See if we have any probes left enabled.
     */
    for (i = 0; i < LS_NPROBES; i++) {
        if (lockstat_probemap[i]) {
            /*
             * This probe is still enabled.  We don't need to deal
             * with waiting for all threads to be out of the
             * lockstat critical sections; just return.
             */
            return;
        }
    }

    /*
     * The delay() here isn't as cheesy as you might think.  We don't
     * want to busy-loop in the kernel, so we have to give up the
     * CPU between calls to lockstat_active_threads(); that much is
     * obvious.  But the reason it's a do..while loop rather than a
     * while loop is subtle.  The memory barrier above guarantees that
     * no threads will enter the lockstat code from this point forward.
     * However, another thread could already be executing lockstat code
     * without our knowledge if the update to its t_lockstat field hasn't
     * cleared its CPU's store buffer.  Delaying for one clock tick
     * guarantees that either (1) the thread will have *ample* time to
     * complete its work, or (2) the thread will be preempted, in which
     * case it will have to grab and release a dispatcher lock, which
     * will flush that CPU's store buffer.  Either way we're covered.
     */
    do {
        delay(1);
    } while (lockstat_active_threads());
}

/*ARGSUSED*/
static int
lockstat_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
{
    return (0);
}

/* ARGSUSED */
static int
lockstat_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
    int error;

    switch (infocmd) {
    case DDI_INFO_DEVT2DEVINFO:
        *result = (void *) lockstat_devi;
        error = DDI_SUCCESS;
        break;
    case DDI_INFO_DEVT2INSTANCE:
        *result = (void *)0;
        error = DDI_SUCCESS;
        break;
    default:
        error = DDI_FAILURE;
    }
    return (error);
}

/*ARGSUSED*/
static void
lockstat_provide(void *arg, const dtrace_probedesc_t *desc)
{
    int i = 0;

    for (i = 0; lockstat_probes[i].lsp_func != NULL; i++) {
        lockstat_probe_t *probe = &lockstat_probes[i];

        if (dtrace_probe_lookup(lockstat_id, "genunix",
            probe->lsp_func, probe->lsp_name) != 0)
            continue;

        ASSERT(!probe->lsp_id);
        probe->lsp_id = dtrace_probe_create(lockstat_id,
            "genunix", probe->lsp_func, probe->lsp_name,
            1, probe);
    }
}

/*ARGSUSED*/
static void
lockstat_destroy(void *arg, dtrace_id_t id, void *parg)
{
    lockstat_probe_t *probe = parg;

    ASSERT(!lockstat_probemap[probe->lsp_probe]);
    probe->lsp_id = 0;
}

static dtrace_pattr_t lockstat_attr = {
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
};

static dtrace_pops_t lockstat_pops = {
    lockstat_provide,
    NULL,
    lockstat_enable,
    lockstat_disable,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    lockstat_destroy
};

static int
lockstat_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
    switch (cmd) {
    case DDI_ATTACH:
        break;
    case DDI_RESUME:
        return (DDI_SUCCESS);
    default:
        return (DDI_FAILURE);
    }

    if (ddi_create_minor_node(devi, "lockstat", S_IFCHR, 0,
        DDI_PSEUDO, 0) == DDI_FAILURE ||
        dtrace_register("lockstat", &lockstat_attr, DTRACE_PRIV_KERNEL, 0,
        &lockstat_pops, NULL, &lockstat_id) != 0) {
        ddi_remove_minor_node(devi, NULL);
        return (DDI_FAILURE);
    }

    ddi_report_dev(devi);
    lockstat_devi = devi;
    return (DDI_SUCCESS);
}

static int
lockstat_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
{
    switch (cmd) {
    case DDI_DETACH:
        break;
    case DDI_SUSPEND:
        return (DDI_SUCCESS);
    default:
        return (DDI_FAILURE);
    }

    if (dtrace_unregister(lockstat_id) != 0)
        return (DDI_FAILURE);

    ddi_remove_minor_node(devi, NULL);
    return (DDI_SUCCESS);
}

/*
 * Configuration data structures
 */
static struct cb_ops lockstat_cb_ops = {
    lockstat_open,      /* open */
    nodev,          /* close */
    nulldev,        /* strategy */
    nulldev,        /* print */
    nodev,          /* dump */
    nodev,          /* read */
    nodev,          /* write */
    nodev,          /* ioctl */
    nodev,          /* devmap */
    nodev,          /* mmap */
    nodev,          /* segmap */
    nochpoll,       /* poll */
    ddi_prop_op,        /* cb_prop_op */
    0,          /* streamtab */
    D_MP | D_NEW        /* Driver compatibility flag */
};

static struct dev_ops lockstat_ops = {
    DEVO_REV,       /* devo_rev, */
    0,          /* refcnt */
    lockstat_info,      /* getinfo */
    nulldev,        /* identify */
    nulldev,        /* probe */
    lockstat_attach,    /* attach */
    lockstat_detach,    /* detach */
    nulldev,        /* reset */
    &lockstat_cb_ops,   /* cb_ops */
    NULL,           /* bus_ops */
};

static struct modldrv modldrv = {
    &mod_driverops,     /* Type of module.  This one is a driver */
    "Lock Statistics %I%",  /* name of module */
    &lockstat_ops,      /* driver ops */
};

static struct modlinkage modlinkage = {
    MODREV_1, (void *)&modldrv, NULL
};

int
_init(void)
{
    return (mod_install(&modlinkage));
}

int
_fini(void)
{
    return (mod_remove(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
    return (mod_info(&modlinkage, modinfop));
}