svn commit: r244014 - head/sys/cam/scsi
Kenneth D. Merry
ken at FreeBSD.org
Sat Dec 8 04:03:06 UTC 2012
Author: ken
Date: Sat Dec 8 04:03:04 2012
New Revision: 244014
URL: http://svnweb.freebsd.org/changeset/base/244014
Log:
Fix a device departure bug for the the pass(4), enc(4), sg(4) and ch(4)
drivers.
The bug occurrs when a userland process has the driver instance
open and the underlying device goes away. We get the devfs
callback that the device node has been destroyed, but not all of
the closes necessary to fully decrement the reference count on the
CAM peripheral.
The reason is that once devfs calls back and says the device has
been destroyed, it is moved off to deadfs, and devfs guarantees
that there will be no more open or close calls. So the solution
is to keep track of how many outstanding open calls there are on
the device, and just release that many references when we get the
callback from devfs.
scsi_pass.c,
scsi_enc.c,
scsi_enc_internal.h: Add an open count to the softc in these
drivers. Increment it on open and
decrement it on close.
When we get a devfs callback to say that
the device node has gone away, decrement
the peripheral reference count by the
number of still outstanding opens.
Make sure we don't access the peripheral
with cam_periph_unlock() after what might
be the final call to
cam_periph_release_locked(). The
peripheral might have been freed, and we
will be dereferencing freed memory.
scsi_ch.c,
scsi_sg.c: For the ch(4) and sg(4) drivers, add the
same changes described above, and in
addition, fix another bug that was
previously fixed in the pass(4) and enc(4)
drivers.
These drivers were calling destroy_dev()
from their cleanup routine, but that could
cause a deadlock because the cleanup
routine could be indirectly called from
the driver's close routine. This would
cause a deadlock, because the device node
is being held open by the active close
call, and can't be destroyed.
Sponsored by: Spectra Logic Corporation
MFC after: 1 week
Modified:
head/sys/cam/scsi/scsi_ch.c
head/sys/cam/scsi/scsi_enc.c
head/sys/cam/scsi/scsi_enc_internal.h
head/sys/cam/scsi/scsi_pass.c
head/sys/cam/scsi/scsi_sg.c
Modified: head/sys/cam/scsi/scsi_ch.c
==============================================================================
--- head/sys/cam/scsi/scsi_ch.c Sat Dec 8 02:37:18 2012 (r244013)
+++ head/sys/cam/scsi/scsi_ch.c Sat Dec 8 04:03:04 2012 (r244014)
@@ -144,7 +144,8 @@ struct ch_softc {
ch_quirks quirks;
union ccb saved_ccb;
struct devstat *device_stats;
- struct cdev *dev;
+ struct cdev *dev;
+ int open_count;
int sc_picker; /* current picker */
@@ -237,6 +238,48 @@ chinit(void)
}
static void
+chdevgonecb(void *arg)
+{
+ struct cam_sim *sim;
+ struct ch_softc *softc;
+ struct cam_periph *periph;
+ int i;
+
+ periph = (struct cam_periph *)arg;
+ sim = periph->sim;
+ softc = (struct ch_softc *)periph->softc;
+
+ KASSERT(softc->open_count >= 0, ("Negative open count %d",
+ softc->open_count));
+
+ mtx_lock(sim->mtx);
+
+ /*
+ * When we get this callback, we will get no more close calls from
+ * devfs. So if we have any dangling opens, we need to release the
+ * reference held for that particular context.
+ */
+ for (i = 0; i < softc->open_count; i++)
+ cam_periph_release_locked(periph);
+
+ softc->open_count = 0;
+
+ /*
+ * Release the reference held for the device node, it is gone now.
+ */
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the final call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ */
+ mtx_unlock(sim->mtx);
+}
+
+static void
choninvalidate(struct cam_periph *periph)
{
struct ch_softc *softc;
@@ -250,6 +293,12 @@ choninvalidate(struct cam_periph *periph
softc->flags |= CH_FLAG_INVALID;
+ /*
+ * Tell devfs this device has gone away, and ask for a callback
+ * when it has cleaned up its state.
+ */
+ destroy_dev_sched_cb(softc->dev, chdevgonecb, periph);
+
xpt_print(periph->path, "lost device\n");
}
@@ -262,10 +311,9 @@ chcleanup(struct cam_periph *periph)
softc = (struct ch_softc *)periph->softc;
xpt_print(periph->path, "removing device entry\n");
+
devstat_remove_entry(softc->device_stats);
- cam_periph_unlock(periph);
- destroy_dev(softc->dev);
- cam_periph_lock(periph);
+
free(softc, M_DEVBUF);
}
@@ -359,6 +407,19 @@ chregister(struct cam_periph *periph, vo
XPORT_DEVSTAT_TYPE(cpi.transport),
DEVSTAT_PRIORITY_OTHER);
+ /*
+ * Acquire a reference to the periph before we create the devfs
+ * instance for it. We'll release this reference once the devfs
+ * instance has been freed.
+ */
+ if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
+ xpt_print(periph->path, "%s: lost periph during "
+ "registration!\n", __func__);
+ cam_periph_lock(periph);
+ return (CAM_REQ_CMP_ERR);
+ }
+
+
/* Register the device */
softc->dev = make_dev(&ch_cdevsw, periph->unit_number, UID_ROOT,
GID_OPERATOR, 0600, "%s%d", periph->periph_name,
@@ -419,6 +480,9 @@ chopen(struct cdev *dev, int flags, int
}
cam_periph_unhold(periph);
+
+ softc->open_count++;
+
cam_periph_unlock(periph);
return(error);
@@ -427,13 +491,36 @@ chopen(struct cdev *dev, int flags, int
static int
chclose(struct cdev *dev, int flag, int fmt, struct thread *td)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct ch_softc *softc;
periph = (struct cam_periph *)dev->si_drv1;
if (periph == NULL)
return(ENXIO);
- cam_periph_release(periph);
+ sim = periph->sim;
+ softc = (struct ch_softc *)periph->softc;
+
+ mtx_lock(sim->mtx);
+
+ softc->open_count--;
+
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ *
+ * cam_periph_release() avoids this problem using the same method,
+ * but we're manually acquiring and dropping the lock here to
+ * protect the open count and avoid another lock acquisition and
+ * release.
+ */
+ mtx_unlock(sim->mtx);
return(0);
}
Modified: head/sys/cam/scsi/scsi_enc.c
==============================================================================
--- head/sys/cam/scsi/scsi_enc.c Sat Dec 8 02:37:18 2012 (r244013)
+++ head/sys/cam/scsi/scsi_enc.c Sat Dec 8 04:03:04 2012 (r244014)
@@ -111,11 +111,40 @@ enc_init(void)
static void
enc_devgonecb(void *arg)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct enc_softc *enc;
+ int i;
periph = (struct cam_periph *)arg;
+ sim = periph->sim;
+ enc = (struct enc_softc *)periph->softc;
+
+ mtx_lock(sim->mtx);
+
+ /*
+ * When we get this callback, we will get no more close calls from
+ * devfs. So if we have any dangling opens, we need to release the
+ * reference held for that particular context.
+ */
+ for (i = 0; i < enc->open_count; i++)
+ cam_periph_release_locked(periph);
- cam_periph_release(periph);
+ enc->open_count = 0;
+
+ /*
+ * Release the reference held for the device node, it is gone now.
+ */
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the final call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ */
+ mtx_unlock(sim->mtx);
}
static void
@@ -262,6 +291,8 @@ enc_open(struct cdev *dev, int flags, in
out:
if (error != 0)
cam_periph_release_locked(periph);
+ else
+ softc->open_count++;
cam_periph_unlock(periph);
@@ -271,13 +302,36 @@ out:
static int
enc_close(struct cdev *dev, int flag, int fmt, struct thread *td)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct enc_softc *enc;
periph = (struct cam_periph *)dev->si_drv1;
if (periph == NULL)
return (ENXIO);
- cam_periph_release(periph);
+ sim = periph->sim;
+ enc = periph->softc;
+
+ mtx_lock(sim->mtx);
+
+ enc->open_count--;
+
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ *
+ * cam_periph_release() avoids this problem using the same method,
+ * but we're manually acquiring and dropping the lock here to
+ * protect the open count and avoid another lock acquisition and
+ * release.
+ */
+ mtx_unlock(sim->mtx);
return (0);
}
@@ -946,6 +1000,11 @@ enc_ctor(struct cam_periph *periph, void
}
}
+ /*
+ * Acquire a reference to the periph before we create the devfs
+ * instance for it. We'll release this reference once the devfs
+ * instance has been freed.
+ */
if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
xpt_print(periph->path, "%s: lost periph during "
"registration!\n", __func__);
Modified: head/sys/cam/scsi/scsi_enc_internal.h
==============================================================================
--- head/sys/cam/scsi/scsi_enc_internal.h Sat Dec 8 02:37:18 2012 (r244013)
+++ head/sys/cam/scsi/scsi_enc_internal.h Sat Dec 8 04:03:04 2012 (r244014)
@@ -148,6 +148,7 @@ struct enc_softc {
union ccb saved_ccb;
struct cdev *enc_dev;
struct cam_periph *periph;
+ int open_count;
/* Bitmap of pending operations. */
uint32_t pending_actions;
Modified: head/sys/cam/scsi/scsi_pass.c
==============================================================================
--- head/sys/cam/scsi/scsi_pass.c Sat Dec 8 02:37:18 2012 (r244013)
+++ head/sys/cam/scsi/scsi_pass.c Sat Dec 8 04:03:04 2012 (r244014)
@@ -76,6 +76,7 @@ struct pass_softc {
pass_flags flags;
u_int8_t pd_type;
union ccb saved_ccb;
+ int open_count;
struct devstat *device_stats;
struct cdev *dev;
struct cdev *alias_dev;
@@ -140,12 +141,43 @@ passinit(void)
static void
passdevgonecb(void *arg)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct pass_softc *softc;
+ int i;
periph = (struct cam_periph *)arg;
+ sim = periph->sim;
+ softc = (struct pass_softc *)periph->softc;
+
+ KASSERT(softc->open_count >= 0, ("Negative open count %d",
+ softc->open_count));
+
+ mtx_lock(sim->mtx);
+
+ /*
+ * When we get this callback, we will get no more close calls from
+ * devfs. So if we have any dangling opens, we need to release the
+ * reference held for that particular context.
+ */
+ for (i = 0; i < softc->open_count; i++)
+ cam_periph_release_locked(periph);
+
+ softc->open_count = 0;
+
+ /*
+ * Release the reference held for the device node, it is gone now.
+ */
+ cam_periph_release_locked(periph);
- xpt_print(periph->path, "%s: devfs entry is gone\n", __func__);
- cam_periph_release(periph);
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the final call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ */
+ mtx_unlock(sim->mtx);
}
static void
@@ -368,7 +400,7 @@ passregister(struct cam_periph *periph,
if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
xpt_print(periph->path, "%s: lost periph during "
"registration!\n", __func__);
- mtx_lock(periph->sim->mtx);
+ cam_periph_lock(periph);
return (CAM_REQ_CMP_ERR);
}
@@ -461,6 +493,8 @@ passopen(struct cdev *dev, int flags, in
return(EINVAL);
}
+ softc->open_count++;
+
cam_periph_unlock(periph);
return (error);
@@ -469,13 +503,36 @@ passopen(struct cdev *dev, int flags, in
static int
passclose(struct cdev *dev, int flag, int fmt, struct thread *td)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct pass_softc *softc;
periph = (struct cam_periph *)dev->si_drv1;
if (periph == NULL)
return (ENXIO);
- cam_periph_release(periph);
+ sim = periph->sim;
+ softc = periph->softc;
+
+ mtx_lock(sim->mtx);
+
+ softc->open_count--;
+
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ *
+ * cam_periph_release() avoids this problem using the same method,
+ * but we're manually acquiring and dropping the lock here to
+ * protect the open count and avoid another lock acquisition and
+ * release.
+ */
+ mtx_unlock(sim->mtx);
return (0);
}
Modified: head/sys/cam/scsi/scsi_sg.c
==============================================================================
--- head/sys/cam/scsi/scsi_sg.c Sat Dec 8 02:37:18 2012 (r244013)
+++ head/sys/cam/scsi/scsi_sg.c Sat Dec 8 04:03:04 2012 (r244014)
@@ -99,6 +99,7 @@ struct sg_rdwr {
struct sg_softc {
sg_state state;
sg_flags flags;
+ int open_count;
struct devstat *device_stats;
TAILQ_HEAD(, sg_rdwr) rdwr_done;
struct cdev *dev;
@@ -169,6 +170,49 @@ sginit(void)
}
static void
+sgdevgonecb(void *arg)
+{
+ struct cam_sim *sim;
+ struct cam_periph *periph;
+ struct sg_softc *softc;
+ int i;
+
+ periph = (struct cam_periph *)arg;
+ sim = periph->sim;
+ softc = (struct sg_softc *)periph->softc;
+
+ KASSERT(softc->open_count >= 0, ("Negative open count %d",
+ softc->open_count));
+
+ mtx_lock(sim->mtx);
+
+ /*
+ * When we get this callback, we will get no more close calls from
+ * devfs. So if we have any dangling opens, we need to release the
+ * reference held for that particular context.
+ */
+ for (i = 0; i < softc->open_count; i++)
+ cam_periph_release_locked(periph);
+
+ softc->open_count = 0;
+
+ /*
+ * Release the reference held for the device node, it is gone now.
+ */
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the final call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ */
+ mtx_unlock(sim->mtx);
+}
+
+
+static void
sgoninvalidate(struct cam_periph *periph)
{
struct sg_softc *softc;
@@ -183,6 +227,12 @@ sgoninvalidate(struct cam_periph *periph
softc->flags |= SG_FLAG_INVALID;
/*
+ * Tell devfs this device has gone away, and ask for a callback
+ * when it has cleaned up its state.
+ */
+ destroy_dev_sched_cb(softc->dev, sgdevgonecb, periph);
+
+ /*
* XXX Return all queued I/O with ENXIO.
* XXX Handle any transactions queued to the card
* with XPT_ABORT_CCB.
@@ -201,10 +251,9 @@ sgcleanup(struct cam_periph *periph)
softc = (struct sg_softc *)periph->softc;
if (bootverbose)
xpt_print(periph->path, "removing device entry\n");
+
devstat_remove_entry(softc->device_stats);
- cam_periph_unlock(periph);
- destroy_dev(softc->dev);
- cam_periph_lock(periph);
+
free(softc, M_DEVBUF);
}
@@ -299,6 +348,18 @@ sgregister(struct cam_periph *periph, vo
DEVSTAT_TYPE_PASS,
DEVSTAT_PRIORITY_PASS);
+ /*
+ * Acquire a reference to the periph before we create the devfs
+ * instance for it. We'll release this reference once the devfs
+ * instance has been freed.
+ */
+ if (cam_periph_acquire(periph) != CAM_REQ_CMP) {
+ xpt_print(periph->path, "%s: lost periph during "
+ "registration!\n", __func__);
+ cam_periph_lock(periph);
+ return (CAM_REQ_CMP_ERR);
+ }
+
/* Register the device */
softc->dev = make_dev(&sg_cdevsw, periph->unit_number,
UID_ROOT, GID_OPERATOR, 0600, "%s%d",
@@ -414,6 +475,8 @@ sgopen(struct cdev *dev, int flags, int
return (ENXIO);
}
+ softc->open_count++;
+
cam_periph_unlock(periph);
return (error);
@@ -422,13 +485,36 @@ sgopen(struct cdev *dev, int flags, int
static int
sgclose(struct cdev *dev, int flag, int fmt, struct thread *td)
{
+ struct cam_sim *sim;
struct cam_periph *periph;
+ struct sg_softc *softc;
periph = (struct cam_periph *)dev->si_drv1;
if (periph == NULL)
return (ENXIO);
- cam_periph_release(periph);
+ sim = periph->sim;
+ softc = periph->softc;
+
+ mtx_lock(sim->mtx);
+
+ softc->open_count--;
+
+ cam_periph_release_locked(periph);
+
+ /*
+ * We reference the SIM lock directly here, instead of using
+ * cam_periph_unlock(). The reason is that the call to
+ * cam_periph_release_locked() above could result in the periph
+ * getting freed. If that is the case, dereferencing the periph
+ * with a cam_periph_unlock() call would cause a page fault.
+ *
+ * cam_periph_release() avoids this problem using the same method,
+ * but we're manually acquiring and dropping the lock here to
+ * protect the open count and avoid another lock acquisition and
+ * release.
+ */
+ mtx_unlock(sim->mtx);
return (0);
}
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