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Track Ref / DeRef and Hold / Unhold that da is doing to track down

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leaks. We assume each source can be taken / dropped only once and
don't recurse. These are only enabled via DA_TRACK_REFS or
INVARIANTS. There appreas to be a reference leak under extreme load,
and these should help us colaberatively work it out. It also documents
better the reference / holding protocol better.

Reviewed by: ken@, scottl@
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D14040
This commit is contained in:
Warner Losh 2018-01-25 21:38:30 +00:00
parent de64cba2c7
commit d047fd281d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=328415
2 changed files with 180 additions and 23 deletions
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200
sys/cam/scsi/scsi_da.c
View File

@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#ifdef _KERNEL
#include "opt_da.h"
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bio.h>
@ -51,6 +52,7 @@ __FBSDID("$FreeBSD$");
#include <sys/sbuf.h>
#include <geom/geom.h>
#include <geom/geom_disk.h>
#include <machine/atomic.h>
#endif /* _KERNEL */
#ifndef _KERNEL
@ -291,6 +293,18 @@ struct disk_params {
#define DA_WORK_TUR (1 << 16)
typedef enum {
DA_REF_OPEN = 1,
DA_REF_OPEN_HOLD,
DA_REF_CLOSE_HOLD,
DA_REF_PROBE_HOLD,
DA_REF_TUR,
DA_REF_GEOM,
DA_REF_SYSCTL,
DA_REF_REPROBE,
DA_REF_MAX /* KEEP LAST */
} da_ref_token;
struct da_softc {
struct cam_iosched_softc *cam_iosched;
struct bio_queue_head delete_run_queue;
@ -335,6 +349,7 @@ struct da_softc {
uint8_t unmap_buf[UNMAP_BUF_SIZE];
struct scsi_read_capacity_data_long rcaplong;
struct callout mediapoll_c;
int ref_flags[DA_REF_MAX];
#ifdef CAM_IO_STATS
struct sysctl_ctx_list sysctl_stats_ctx;
struct sysctl_oid *sysctl_stats_tree;
@ -1469,6 +1484,143 @@ PERIPHDRIVER_DECLARE(da, dadriver);
static MALLOC_DEFINE(M_SCSIDA, "scsi_da", "scsi_da buffers");
/*
* This driver takes out references / holds in well defined pairs, never
* recursively. These macros / inline functions enforce those rules. They
* are only enabled with DA_TRACK_REFS or INVARIANTS. If DA_TRACK_REFS is
* defined to be 2 or larger, the tracking also includes debug printfs.
*/
#if defined(DA_TRACK_REFS) || defined(INVARIANTS)
#ifndef DA_TRACK_REFS
#define DA_TRACK_REFS 1
#endif
#if DA_TRACK_REFS > 1
#define CAM_PERIPH_PRINT(p, msg, args...) \
printf("%s%d:" msg, (periph)->periph_name, (periph)->unit_number, ##args)
static const char *da_ref_text[] = {
"bogus",
"open",
"open hold",
"close hold",
"reprobe hold",
"Test Unit Ready",
"Geom",
"sysctl",
"reprobe",
"max -- also bogus"
};
#else
#define CAM_PERIPH_PRINT(p, msg, args...)
#endif
static inline void
token_sanity(da_ref_token token)
{
if ((unsigned)token >= DA_REF_MAX)
panic("Bad token value passed in %d\n", token);
}
static inline int
da_periph_hold(struct cam_periph *periph, int priority, da_ref_token token)
{
int err = cam_periph_hold(periph, priority);
token_sanity(token);
CAM_PERIPH_PRINT(periph, "Holding device %s (%d): %d\n",
da_ref_text[token], token, err);
if (err == 0) {
int cnt;
struct da_softc *softc = periph->softc;
cnt = atomic_fetchadd_int(&softc->ref_flags[token], 1);
if (cnt != 0)
panic("Re-holding for reason %d, cnt = %d", token, cnt);
}
return (err);
}
static inline void
da_periph_unhold(struct cam_periph *periph, da_ref_token token)
{
int cnt;
struct da_softc *softc = periph->softc;
token_sanity(token);
cam_periph_unhold(periph);
CAM_PERIPH_PRINT(periph, "Unholding device %s (%d)\n",
da_ref_text[token], token);
cnt = atomic_fetchadd_int(&softc->ref_flags[token], -1);
if (cnt != 1)
panic("Unholding %d with cnt = %d", token, cnt);
}
static inline int
da_periph_acquire(struct cam_periph *periph, da_ref_token token)
{
int err = cam_periph_acquire(periph);
token_sanity(token);
CAM_PERIPH_PRINT(periph, "acquiring device %s (%d): %d\n",
da_ref_text[token], token, err);
if (err == CAM_REQ_CMP) {
int cnt;
struct da_softc *softc = periph->softc;
cnt = atomic_fetchadd_int(&softc->ref_flags[token], 1);
if (cnt != 0)
panic("Re-refing for reason %d, cnt = %d", token, cnt);
}
return (err);
}
static inline void
da_periph_release(struct cam_periph *periph, da_ref_token token)
{
int cnt;
struct da_softc *softc = periph->softc;
token_sanity(token);
cam_periph_release(periph);
CAM_PERIPH_PRINT(periph, "releasing device %s (%d)\n",
da_ref_text[token], token);
cnt = atomic_fetchadd_int(&softc->ref_flags[token], -1);
if (cnt != 1)
panic("Unholding %d with cnt = %d", token, cnt);
}
static inline void
da_periph_release_locked(struct cam_periph *periph, da_ref_token token)
{
int cnt;
struct da_softc *softc = periph->softc;
token_sanity(token);
cam_periph_release_locked(periph);
CAM_PERIPH_PRINT(periph, "releasing device (locked) %s (%d)\n",
da_ref_text[token], token);
cnt = atomic_fetchadd_int(&softc->ref_flags[token], -1);
if (cnt != 1)
panic("Unholding %d with cnt = %d", token, cnt);
}
#define cam_periph_hold POISON
#define cam_periph_unhold POISON
#define cam_periph_acquire POISON
#define cam_periph_release POISON
#define cam_periph_release_locked POISON
#else
#define da_periph_hold(periph, prio, token) cam_periph_hold((periph), (prio))
#define da_periph_unhold(periph, token) cam_periph_unhold((periph))
#define da_periph_acquire(periph, token) cam_periph_acquire((periph))
#define da_periph_release(periph, token) cam_periph_release((periph))
#define da_periph_release_locked(periph, token) cam_periph_release_locked((periph))
#endif
static int
daopen(struct disk *dp)
{
@ -1477,14 +1629,14 @@ daopen(struct disk *dp)
int error;
periph = (struct cam_periph *)dp->d_drv1;
if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
if (da_periph_acquire(periph, DA_REF_OPEN) != CAM_REQ_CMP) {
return (ENXIO);
}
cam_periph_lock(periph);
if ((error = cam_periph_hold(periph, PRIBIO|PCATCH)) != 0) {
if ((error = da_periph_hold(periph, PRIBIO|PCATCH, DA_REF_OPEN_HOLD)) != 0) {
cam_periph_unlock(periph);
cam_periph_release(periph);
da_periph_release(periph, DA_REF_OPEN);
return (error);
}
@ -1512,11 +1664,11 @@ daopen(struct disk *dp)
softc->flags |= DA_FLAG_OPEN;
}
cam_periph_unhold(periph);
da_periph_unhold(periph, DA_REF_OPEN_HOLD);
cam_periph_unlock(periph);
if (error != 0)
cam_periph_release(periph);
da_periph_release(periph, DA_REF_OPEN);
return (error);
}
@ -1534,7 +1686,7 @@ daclose(struct disk *dp)
CAM_DEBUG(periph->path, CAM_DEBUG_TRACE | CAM_DEBUG_PERIPH,
("daclose\n"));
if (cam_periph_hold(periph, PRIBIO) == 0) {
if (da_periph_hold(periph, PRIBIO, DA_REF_CLOSE_HOLD) == 0) {
/* Flush disk cache. */
if ((softc->flags & DA_FLAG_DIRTY) != 0 &&
@ -1557,7 +1709,7 @@ daclose(struct disk *dp)
(softc->quirks & DA_Q_NO_PREVENT) == 0)
daprevent(periph, PR_ALLOW);
cam_periph_unhold(periph);
da_periph_unhold(periph, DA_REF_CLOSE_HOLD);
}
/*
@ -1572,7 +1724,7 @@ daclose(struct disk *dp)
while (softc->refcount != 0)
cam_periph_sleep(periph, &softc->refcount, PRIBIO, "daclose", 1);
cam_periph_unlock(periph);
cam_periph_release(periph);
da_periph_release(periph, DA_REF_OPEN);
return (0);
}
@ -1750,7 +1902,7 @@ dadiskgonecb(struct disk *dp)
struct cam_periph *periph;
periph = (struct cam_periph *)dp->d_drv1;
cam_periph_release(periph);
da_periph_release(periph, DA_REF_GEOM);
}
static void
@ -1910,7 +2062,7 @@ daasync(void *callback_arg, u_int32_t code,
case AC_SCSI_AEN:
softc = (struct da_softc *)periph->softc;
if (!cam_iosched_has_work_flags(softc->cam_iosched, DA_WORK_TUR)) {
if (cam_periph_acquire(periph) == CAM_REQ_CMP) {
if (da_periph_acquire(periph, DA_REF_TUR) == CAM_REQ_CMP) {
cam_iosched_set_work_flags(softc->cam_iosched, DA_WORK_TUR);
daschedule(periph);
}
@ -1955,7 +2107,7 @@ dasysctlinit(void *context, int pending)
* periph was held for us when this task was enqueued
*/
if (periph->flags & CAM_PERIPH_INVALID) {
cam_periph_release(periph);
da_periph_release(periph, DA_REF_SYSCTL);
return;
}
@ -1970,7 +2122,7 @@ dasysctlinit(void *context, int pending)
CTLFLAG_RD, 0, tmpstr, "device_index");
if (softc->sysctl_tree == NULL) {
printf("dasysctlinit: unable to allocate sysctl tree\n");
cam_periph_release(periph);
da_periph_release(periph, DA_REF_SYSCTL);
return;
}
@ -2052,7 +2204,7 @@ dasysctlinit(void *context, int pending)
xpt_action((union ccb *)&cts);
cam_periph_unlock(periph);
if (cts.ccb_h.status != CAM_REQ_CMP) {
cam_periph_release(periph);
da_periph_release(periph, DA_REF_SYSCTL);
return;
}
if (cts.protocol == PROTO_SCSI && cts.transport == XPORT_FC) {
@ -2103,7 +2255,7 @@ dasysctlinit(void *context, int pending)
cam_iosched_sysctl_init(softc->cam_iosched, &softc->sysctl_ctx,
softc->sysctl_tree);
cam_periph_release(periph);
da_periph_release(periph, DA_REF_SYSCTL);
}
static int
@ -2269,9 +2421,9 @@ daprobedone(struct cam_periph *periph, union ccb *ccb)
wakeup(&softc->disk->d_mediasize);
if ((softc->flags & DA_FLAG_ANNOUNCED) == 0) {
softc->flags |= DA_FLAG_ANNOUNCED;
cam_periph_unhold(periph);
da_periph_unhold(periph, DA_REF_PROBE_HOLD);
} else
cam_periph_release_locked(periph);
da_periph_release_locked(periph, DA_REF_REPROBE);
}
static void
@ -2484,8 +2636,10 @@ daregister(struct cam_periph *periph, void *arg)
* Take an exclusive refcount on the periph while dastart is called
* to finish the probe. The reference will be dropped in dadone at
* the end of probe.
*
* XXX if cam_periph_hold returns an error, we don't hold a refcount.
*/
(void)cam_periph_hold(periph, PRIBIO);
(void)da_periph_hold(periph, PRIBIO, DA_REF_PROBE_HOLD);
/*
* Schedule a periodic event to occasionally send an
@ -2579,7 +2733,7 @@ daregister(struct cam_periph *periph, void *arg)
* We'll release this reference once GEOM calls us back (via
* dadiskgonecb()) telling us that our provider has been freed.
*/
if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
if (da_periph_acquire(periph, DA_REF_GEOM) != CAM_REQ_CMP) {
xpt_print(periph->path, "%s: lost periph during "
"registration!\n", __func__);
cam_periph_lock(periph);
@ -2965,7 +3119,7 @@ dastart(struct cam_periph *periph, union ccb *start_ccb)
if (cam_iosched_has_work_flags(softc->cam_iosched, DA_WORK_TUR)) {
cam_iosched_clr_work_flags(softc->cam_iosched, DA_WORK_TUR);
cam_periph_release_locked(periph);
da_periph_release_locked(periph, DA_REF_TUR);
}
if ((bp->bio_flags & BIO_ORDERED) != 0 ||
@ -4547,7 +4701,7 @@ dadone(struct cam_periph *periph, union ccb *done_ccb)
* we have successfully attached.
*/
/* increase the refcount */
if (cam_periph_acquire(periph) == CAM_REQ_CMP) {
if (da_periph_acquire(periph, DA_REF_SYSCTL) == CAM_REQ_CMP) {
taskqueue_enqueue(taskqueue_thread,
&softc->sysctl_task);
@ -5392,7 +5546,7 @@ dadone(struct cam_periph *periph, union ccb *done_ccb)
/*getcount_only*/0);
}
xpt_release_ccb(done_ccb);
cam_periph_release_locked(periph);
da_periph_release_locked(periph, DA_REF_TUR);
return;
}
default:
@ -5413,7 +5567,7 @@ dareprobe(struct cam_periph *periph)
if (softc->state != DA_STATE_NORMAL)
return;
status = cam_periph_acquire(periph);
status = da_periph_acquire(periph, DA_REF_REPROBE);
KASSERT(status == CAM_REQ_CMP,
("dareprobe: cam_periph_acquire failed"));
@ -5513,7 +5667,7 @@ damediapoll(void *arg)
if (!cam_iosched_has_work_flags(softc->cam_iosched, DA_WORK_TUR) &&
LIST_EMPTY(&softc->pending_ccbs)) {
if (cam_periph_acquire(periph) == CAM_REQ_CMP) {
if (da_periph_acquire(periph, DA_REF_TUR) == CAM_REQ_CMP) {
cam_iosched_set_work_flags(softc->cam_iosched, DA_WORK_TUR);
daschedule(periph);
}

3
sys/conf/options
View File

@ -345,6 +345,9 @@ ATA_STATIC_ID opt_ada.h
CHANGER_MIN_BUSY_SECONDS opt_cd.h
CHANGER_MAX_BUSY_SECONDS opt_cd.h
# Options used only in cam/scsi/scsi_da.c
DA_TRACK_REFS opt_da.h
# Options used only in cam/scsi/scsi_sa.c.
SA_IO_TIMEOUT opt_sa.h
SA_SPACE_TIMEOUT opt_sa.h