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-rw-r--r--sys/kern/subr_devstat.c541
1 files changed, 541 insertions, 0 deletions
diff --git a/sys/kern/subr_devstat.c b/sys/kern/subr_devstat.c
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+++ b/sys/kern/subr_devstat.c
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+/*
+ * Copyright (c) 1997, 1998, 1999 Kenneth D. Merry.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+#include <sys/bio.h>
+#include <sys/devicestat.h>
+#include <sys/sysctl.h>
+#include <sys/malloc.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/conf.h>
+#include <vm/vm.h>
+#include <vm/pmap.h>
+
+#include <machine/atomic.h>
+
+static int devstat_num_devs;
+static long devstat_generation;
+static int devstat_version = DEVSTAT_VERSION;
+static int devstat_current_devnumber;
+static struct mtx devstat_mutex;
+
+static struct devstatlist device_statq;
+static struct devstat *devstat_alloc(void);
+static void devstat_free(struct devstat *);
+static void devstat_add_entry(struct devstat *ds, const void *dev_name,
+ int unit_number, u_int32_t block_size,
+ devstat_support_flags flags,
+ devstat_type_flags device_type,
+ devstat_priority priority);
+
+/*
+ * Allocate a devstat and initialize it
+ */
+struct devstat *
+devstat_new_entry(const void *dev_name,
+ int unit_number, u_int32_t block_size,
+ devstat_support_flags flags,
+ devstat_type_flags device_type,
+ devstat_priority priority)
+{
+ struct devstat *ds;
+ static int once;
+
+ if (!once) {
+ STAILQ_INIT(&device_statq);
+ mtx_init(&devstat_mutex, "devstat", NULL, MTX_DEF);
+ once = 1;
+ }
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ ds = devstat_alloc();
+ mtx_lock(&devstat_mutex);
+ if (unit_number == -1) {
+ ds->id = dev_name;
+ binuptime(&ds->creation_time);
+ devstat_generation++;
+ } else {
+ devstat_add_entry(ds, dev_name, unit_number, block_size,
+ flags, device_type, priority);
+ }
+ mtx_unlock(&devstat_mutex);
+ return (ds);
+}
+
+/*
+ * Take a malloced and zeroed devstat structure given to us, fill it in
+ * and add it to the queue of devices.
+ */
+static void
+devstat_add_entry(struct devstat *ds, const void *dev_name,
+ int unit_number, u_int32_t block_size,
+ devstat_support_flags flags,
+ devstat_type_flags device_type,
+ devstat_priority priority)
+{
+ struct devstatlist *devstat_head;
+ struct devstat *ds_tmp;
+
+ mtx_assert(&devstat_mutex, MA_OWNED);
+ devstat_num_devs++;
+
+ devstat_head = &device_statq;
+
+ /*
+ * Priority sort. Each driver passes in its priority when it adds
+ * its devstat entry. Drivers are sorted first by priority, and
+ * then by probe order.
+ *
+ * For the first device, we just insert it, since the priority
+ * doesn't really matter yet. Subsequent devices are inserted into
+ * the list using the order outlined above.
+ */
+ if (devstat_num_devs == 1)
+ STAILQ_INSERT_TAIL(devstat_head, ds, dev_links);
+ else {
+ STAILQ_FOREACH(ds_tmp, devstat_head, dev_links) {
+ struct devstat *ds_next;
+
+ ds_next = STAILQ_NEXT(ds_tmp, dev_links);
+
+ /*
+ * If we find a break between higher and lower
+ * priority items, and if this item fits in the
+ * break, insert it. This also applies if the
+ * "lower priority item" is the end of the list.
+ */
+ if ((priority <= ds_tmp->priority)
+ && ((ds_next == NULL)
+ || (priority > ds_next->priority))) {
+ STAILQ_INSERT_AFTER(devstat_head, ds_tmp, ds,
+ dev_links);
+ break;
+ } else if (priority > ds_tmp->priority) {
+ /*
+ * If this is the case, we should be able
+ * to insert ourselves at the head of the
+ * list. If we can't, something is wrong.
+ */
+ if (ds_tmp == STAILQ_FIRST(devstat_head)) {
+ STAILQ_INSERT_HEAD(devstat_head,
+ ds, dev_links);
+ break;
+ } else {
+ STAILQ_INSERT_TAIL(devstat_head,
+ ds, dev_links);
+ printf("devstat_add_entry: HELP! "
+ "sorting problem detected "
+ "for name %p unit %d\n",
+ dev_name, unit_number);
+ break;
+ }
+ }
+ }
+ }
+
+ ds->device_number = devstat_current_devnumber++;
+ ds->unit_number = unit_number;
+ strlcpy(ds->device_name, dev_name, DEVSTAT_NAME_LEN);
+ ds->block_size = block_size;
+ ds->flags = flags;
+ ds->device_type = device_type;
+ ds->priority = priority;
+ binuptime(&ds->creation_time);
+ devstat_generation++;
+}
+
+/*
+ * Remove a devstat structure from the list of devices.
+ */
+void
+devstat_remove_entry(struct devstat *ds)
+{
+ struct devstatlist *devstat_head;
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+ if (ds == NULL)
+ return;
+
+ mtx_lock(&devstat_mutex);
+
+ devstat_head = &device_statq;
+
+ /* Remove this entry from the devstat queue */
+ atomic_add_acq_int(&ds->sequence1, 1);
+ if (ds->id == NULL) {
+ devstat_num_devs--;
+ STAILQ_REMOVE(devstat_head, ds, devstat, dev_links);
+ }
+ devstat_free(ds);
+ devstat_generation++;
+ mtx_unlock(&devstat_mutex);
+}
+
+/*
+ * Record a transaction start.
+ *
+ * See comments for devstat_end_transaction(). Ordering is very important
+ * here.
+ */
+void
+devstat_start_transaction(struct devstat *ds, struct bintime *now)
+{
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ /* sanity check */
+ if (ds == NULL)
+ return;
+
+ atomic_add_acq_int(&ds->sequence1, 1);
+ /*
+ * We only want to set the start time when we are going from idle
+ * to busy. The start time is really the start of the latest busy
+ * period.
+ */
+ if (ds->start_count == ds->end_count) {
+ if (now != NULL)
+ ds->busy_from = *now;
+ else
+ binuptime(&ds->busy_from);
+ }
+ ds->start_count++;
+ atomic_add_rel_int(&ds->sequence0, 1);
+}
+
+void
+devstat_start_transaction_bio(struct devstat *ds, struct bio *bp)
+{
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ /* sanity check */
+ if (ds == NULL)
+ return;
+
+ binuptime(&bp->bio_t0);
+ devstat_start_transaction(ds, &bp->bio_t0);
+}
+
+/*
+ * Record the ending of a transaction, and incrment the various counters.
+ *
+ * Ordering in this function, and in devstat_start_transaction() is VERY
+ * important. The idea here is to run without locks, so we are very
+ * careful to only modify some fields on the way "down" (i.e. at
+ * transaction start) and some fields on the way "up" (i.e. at transaction
+ * completion). One exception is busy_from, which we only modify in
+ * devstat_start_transaction() when there are no outstanding transactions,
+ * and thus it can't be modified in devstat_end_transaction()
+ * simultaneously.
+ *
+ * The sequence0 and sequence1 fields are provided to enable an application
+ * spying on the structures with mmap(2) to tell when a structure is in a
+ * consistent state or not.
+ *
+ * For this to work 100% reliably, it is important that the two fields
+ * are at opposite ends of the structure and that they are incremented
+ * in the opposite order of how a memcpy(3) in userland would copy them.
+ * We assume that the copying happens front to back, but there is actually
+ * no way short of writing your own memcpy(3) replacement to guarantee
+ * this will be the case.
+ *
+ * In addition to this, being a kind of locks, they must be updated with
+ * atomic instructions using appropriate memory barriers.
+ */
+void
+devstat_end_transaction(struct devstat *ds, u_int32_t bytes,
+ devstat_tag_type tag_type, devstat_trans_flags flags,
+ struct bintime *now, struct bintime *then)
+{
+ struct bintime dt, lnow;
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ /* sanity check */
+ if (ds == NULL)
+ return;
+
+ if (now == NULL) {
+ now = &lnow;
+ binuptime(now);
+ }
+
+ atomic_add_acq_int(&ds->sequence1, 1);
+ /* Update byte and operations counts */
+ ds->bytes[flags] += bytes;
+ ds->operations[flags]++;
+
+ /*
+ * Keep a count of the various tag types sent.
+ */
+ if ((ds->flags & DEVSTAT_NO_ORDERED_TAGS) == 0 &&
+ tag_type != DEVSTAT_TAG_NONE)
+ ds->tag_types[tag_type]++;
+
+ if (then != NULL) {
+ /* Update duration of operations */
+ dt = *now;
+ bintime_sub(&dt, then);
+ bintime_add(&ds->duration[flags], &dt);
+ }
+
+ /* Accumulate busy time */
+ dt = *now;
+ bintime_sub(&dt, &ds->busy_from);
+ bintime_add(&ds->busy_time, &dt);
+ ds->busy_from = *now;
+
+ ds->end_count++;
+ atomic_add_rel_int(&ds->sequence0, 1);
+}
+
+void
+devstat_end_transaction_bio(struct devstat *ds, struct bio *bp)
+{
+ devstat_trans_flags flg;
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ /* sanity check */
+ if (ds == NULL)
+ return;
+
+ if (bp->bio_cmd == BIO_DELETE)
+ flg = DEVSTAT_FREE;
+ else if (bp->bio_cmd == BIO_READ)
+ flg = DEVSTAT_READ;
+ else if (bp->bio_cmd == BIO_WRITE)
+ flg = DEVSTAT_WRITE;
+ else
+ flg = DEVSTAT_NO_DATA;
+
+ devstat_end_transaction(ds, bp->bio_bcount - bp->bio_resid,
+ DEVSTAT_TAG_SIMPLE, flg, NULL, &bp->bio_t0);
+}
+
+/*
+ * This is the sysctl handler for the devstat package. The data pushed out
+ * on the kern.devstat.all sysctl variable consists of the current devstat
+ * generation number, and then an array of devstat structures, one for each
+ * device in the system.
+ *
+ * This is more cryptic that obvious, but basically we neither can nor
+ * want to hold the devstat_mutex for any amount of time, so we grab it
+ * only when we need to and keep an eye on devstat_generation all the time.
+ */
+static int
+sysctl_devstat(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+ long mygen;
+ struct devstat *nds;
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+
+ if (devstat_num_devs == 0)
+ return(EINVAL);
+
+ /*
+ * XXX devstat_generation should really be "volatile" but that
+ * XXX freaks out the sysctl macro below. The places where we
+ * XXX change it and inspect it are bracketed in the mutex which
+ * XXX guarantees us proper write barriers. I don't belive the
+ * XXX compiler is allowed to optimize mygen away across calls
+ * XXX to other functions, so the following is belived to be safe.
+ */
+ mygen = devstat_generation;
+
+ error = SYSCTL_OUT(req, &mygen, sizeof(mygen));
+
+ if (error != 0)
+ return (error);
+
+ mtx_lock(&devstat_mutex);
+ nds = STAILQ_FIRST(&device_statq);
+ if (mygen != devstat_generation)
+ error = EBUSY;
+ mtx_unlock(&devstat_mutex);
+
+ if (error != 0)
+ return (error);
+
+ for (;nds != NULL;) {
+ error = SYSCTL_OUT(req, nds, sizeof(struct devstat));
+ if (error != 0)
+ return (error);
+ mtx_lock(&devstat_mutex);
+ if (mygen != devstat_generation)
+ error = EBUSY;
+ else
+ nds = STAILQ_NEXT(nds, dev_links);
+ mtx_unlock(&devstat_mutex);
+ if (error != 0)
+ return (error);
+ }
+ return(error);
+}
+
+/*
+ * Sysctl entries for devstat. The first one is a node that all the rest
+ * hang off of.
+ */
+SYSCTL_NODE(_kern, OID_AUTO, devstat, CTLFLAG_RD, 0, "Device Statistics");
+
+SYSCTL_PROC(_kern_devstat, OID_AUTO, all, CTLFLAG_RD|CTLTYPE_OPAQUE,
+ 0, 0, sysctl_devstat, "S,devstat", "All devices in the devstat list");
+/*
+ * Export the number of devices in the system so that userland utilities
+ * can determine how much memory to allocate to hold all the devices.
+ */
+SYSCTL_INT(_kern_devstat, OID_AUTO, numdevs, CTLFLAG_RD,
+ &devstat_num_devs, 0, "Number of devices in the devstat list");
+SYSCTL_LONG(_kern_devstat, OID_AUTO, generation, CTLFLAG_RD,
+ &devstat_generation, 0, "Devstat list generation");
+SYSCTL_INT(_kern_devstat, OID_AUTO, version, CTLFLAG_RD,
+ &devstat_version, 0, "Devstat list version number");
+
+/*
+ * Allocator for struct devstat structures. We sub-allocate these from pages
+ * which we get from malloc. These pages are exported for mmap(2)'ing through
+ * a miniature device driver
+ */
+
+#define statsperpage (PAGE_SIZE / sizeof(struct devstat))
+
+static d_mmap_t devstat_mmap;
+
+static struct cdevsw devstat_cdevsw = {
+ .d_open = nullopen,
+ .d_close = nullclose,
+ .d_mmap = devstat_mmap,
+ .d_name = "devstat",
+};
+
+struct statspage {
+ TAILQ_ENTRY(statspage) list;
+ struct devstat *stat;
+ u_int nfree;
+};
+
+static TAILQ_HEAD(, statspage) pagelist = TAILQ_HEAD_INITIALIZER(pagelist);
+static MALLOC_DEFINE(M_DEVSTAT, "devstat", "Device statistics");
+
+static int
+devstat_mmap(dev_t dev, vm_offset_t offset, vm_paddr_t *paddr, int nprot)
+{
+ struct statspage *spp;
+
+ if (nprot != VM_PROT_READ)
+ return (-1);
+ TAILQ_FOREACH(spp, &pagelist, list) {
+ if (offset == 0) {
+ *paddr = vtophys(spp->stat);
+ return (0);
+ }
+ offset -= PAGE_SIZE;
+ }
+ return (-1);
+}
+
+static struct devstat *
+devstat_alloc(void)
+{
+ struct devstat *dsp;
+ struct statspage *spp;
+ u_int u;
+ static int once;
+
+ mtx_assert(&devstat_mutex, MA_NOTOWNED);
+ if (!once) {
+ make_dev(&devstat_cdevsw, 0,
+ UID_ROOT, GID_WHEEL, 0400, DEVSTAT_DEVICE_NAME);
+ once = 1;
+ }
+ mtx_lock(&devstat_mutex);
+ for (;;) {
+ TAILQ_FOREACH(spp, &pagelist, list) {
+ if (spp->nfree > 0)
+ break;
+ }
+ if (spp != NULL)
+ break;
+ /*
+ * We had no free slot in any of our pages, drop the mutex
+ * and get another page. In theory we could have more than
+ * one process doing this at the same time and consequently
+ * we may allocate more pages than we will need. That is
+ * Just Too Bad[tm], we can live with that.
+ */
+ mtx_unlock(&devstat_mutex);
+ spp = malloc(sizeof *spp, M_DEVSTAT, M_ZERO | M_WAITOK);
+ spp->stat = malloc(PAGE_SIZE, M_DEVSTAT, M_ZERO | M_WAITOK);
+ spp->nfree = statsperpage;
+ mtx_lock(&devstat_mutex);
+ /*
+ * It would make more sense to add the new page at the head
+ * but the order on the list determine the sequence of the
+ * mapping so we can't do that.
+ */
+ TAILQ_INSERT_TAIL(&pagelist, spp, list);
+ }
+ dsp = spp->stat;
+ for (u = 0; u < statsperpage; u++) {
+ if (dsp->allocated == 0)
+ break;
+ dsp++;
+ }
+ spp->nfree--;
+ dsp->allocated = 1;
+ mtx_unlock(&devstat_mutex);
+ return (dsp);
+}
+
+static void
+devstat_free(struct devstat *dsp)
+{
+ struct statspage *spp;
+
+ mtx_assert(&devstat_mutex, MA_OWNED);
+ bzero(dsp, sizeof *dsp);
+ TAILQ_FOREACH(spp, &pagelist, list) {
+ if (dsp >= spp->stat && dsp < (spp->stat + statsperpage)) {
+ spp->nfree++;
+ return;
+ }
+ }
+}
+
+SYSCTL_INT(_debug_sizeof, OID_AUTO, devstat, CTLFLAG_RD,
+ 0, sizeof(struct devstat), "sizeof(struct devstat)");
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