git: 25c49c426c6b - main - Revert "Make device_busy/unbusy work w/o Giant held"
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Date: Tue, 30 Nov 2021 22:21:03 UTC
The branch main has been updated by imp:
URL: https://cgit.FreeBSD.org/src/commit/?id=25c49c426c6b6067f7374fae39fb38333cd11e0c
commit 25c49c426c6b6067f7374fae39fb38333cd11e0c
Author: Warner Losh <imp@FreeBSD.org>
AuthorDate: 2021-11-30 22:12:22 +0000
Commit: Warner Losh <imp@FreeBSD.org>
CommitDate: 2021-11-30 22:17:07 +0000
Revert "Make device_busy/unbusy work w/o Giant held"
This reverts commit 08e781915363f98f4318a864b3b5a52bd99424c6.
Commit message was for a very old version of the patch. Will re-commit
with the right one since it's so bad. There's no locked versions of
it...that code was reworked to use refcnt APIs.
Noticed by: jhb, jtrc27
Sponsored by: Netflix
---
sys/dev/drm2/drm_fops.c | 6 ++++++
sys/dev/gpio/gpiopps.c | 9 +++++++--
sys/dev/pccard/pccard.c | 2 +-
sys/kern/subr_bus.c | 41 ++++++++++++++++++++++++-----------------
sys/sys/bus.h | 1 +
5 files changed, 39 insertions(+), 20 deletions(-)
diff --git a/sys/dev/drm2/drm_fops.c b/sys/dev/drm2/drm_fops.c
index 0c8b71759292..3b3be06345e5 100644
--- a/sys/dev/drm2/drm_fops.c
+++ b/sys/dev/drm2/drm_fops.c
@@ -157,7 +157,9 @@ int drm_open(struct cdev *kdev, int flags, int fmt, DRM_STRUCTPROC *p)
return 0;
err_undo:
+ mtx_lock(&Giant); /* FIXME: Giant required? */
device_unbusy(dev->dev);
+ mtx_unlock(&Giant);
dev->open_count--;
sx_xunlock(&drm_global_mutex);
return -retcode;
@@ -271,7 +273,9 @@ static int drm_open_helper(struct cdev *kdev, int flags, int fmt,
list_add(&priv->lhead, &dev->filelist);
DRM_UNLOCK(dev);
+ mtx_lock(&Giant); /* FIXME: Giant required? */
device_busy(dev->dev);
+ mtx_unlock(&Giant);
ret = devfs_set_cdevpriv(priv, drm_release);
if (ret != 0)
@@ -449,7 +453,9 @@ void drm_release(void *data)
*/
atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
+ mtx_lock(&Giant);
device_unbusy(dev->dev);
+ mtx_unlock(&Giant);
if (!--dev->open_count) {
if (atomic_read(&dev->ioctl_count)) {
DRM_ERROR("Device busy: %d\n",
diff --git a/sys/dev/gpio/gpiopps.c b/sys/dev/gpio/gpiopps.c
index 741bfa4498a6..4700acf19bcd 100644
--- a/sys/dev/gpio/gpiopps.c
+++ b/sys/dev/gpio/gpiopps.c
@@ -73,7 +73,9 @@ gpiopps_open(struct cdev *dev, int flags, int fmt, struct thread *td)
/* We can't be unloaded while open, so mark ourselves BUSY. */
mtx_lock(&sc->pps_mtx);
- device_busy(sc->dev);
+ if (device_get_state(sc->dev) < DS_BUSY) {
+ device_busy(sc->dev);
+ }
mtx_unlock(&sc->pps_mtx);
return 0;
@@ -84,6 +86,10 @@ gpiopps_close(struct cdev *dev, int flags, int fmt, struct thread *td)
{
struct pps_softc *sc = dev->si_drv1;
+ /*
+ * Un-busy on last close. We rely on the vfs counting stuff to only call
+ * this routine on last-close, so we don't need any open-count logic.
+ */
mtx_lock(&sc->pps_mtx);
device_unbusy(sc->dev);
mtx_unlock(&sc->pps_mtx);
@@ -107,7 +113,6 @@ gpiopps_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thre
static struct cdevsw pps_cdevsw = {
.d_version = D_VERSION,
- .d_flags = D_TRACKCLOSE,
.d_open = gpiopps_open,
.d_close = gpiopps_close,
.d_ioctl = gpiopps_ioctl,
diff --git a/sys/dev/pccard/pccard.c b/sys/dev/pccard/pccard.c
index 48d2e6973a38..8f19eb84725c 100644
--- a/sys/dev/pccard/pccard.c
+++ b/sys/dev/pccard/pccard.c
@@ -342,7 +342,7 @@ pccard_detach_card(device_t dev)
if (pf->dev == NULL)
continue;
state = device_get_state(pf->dev);
- if (state == DS_ATTACHED)
+ if (state == DS_ATTACHED || state == DS_BUSY)
device_detach(pf->dev);
if (pf->cfe != NULL)
pccard_function_disable(pf);
diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index ab7de881d57d..09072e1a23de 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -51,7 +51,6 @@ __FBSDID("$FreeBSD$");
#include <sys/queue.h>
#include <machine/bus.h>
#include <sys/random.h>
-#include <sys/refcount.h>
#include <sys/rman.h>
#include <sys/sbuf.h>
#include <sys/selinfo.h>
@@ -141,7 +140,7 @@ struct _device {
int unit; /**< current unit number */
char* nameunit; /**< name+unit e.g. foodev0 */
char* desc; /**< driver specific description */
- u_int busy; /**< count of calls to device_busy() */
+ int busy; /**< count of calls to device_busy() */
device_state_t state; /**< current device state */
uint32_t devflags; /**< api level flags for device_get_flags() */
u_int flags; /**< internal device flags */
@@ -2635,13 +2634,13 @@ device_disable(device_t dev)
void
device_busy(device_t dev)
{
-
- /*
- * Mark the device as busy, recursively up the tree if this busy count
- * goes 0->1.
- */
- if (refcount_acquire(&dev->busy) == 0 && dev->parent != NULL)
+ if (dev->state < DS_ATTACHING)
+ panic("device_busy: called for unattached device");
+ if (dev->busy == 0 && dev->parent)
device_busy(dev->parent);
+ dev->busy++;
+ if (dev->state == DS_ATTACHED)
+ dev->state = DS_BUSY;
}
/**
@@ -2650,12 +2649,17 @@ device_busy(device_t dev)
void
device_unbusy(device_t dev)
{
-
- /*
- * Mark the device as unbsy, recursively if this is the last busy count.
- */
- if (refcount_release(&dev->busy) && dev->parent != NULL)
- device_unbusy(dev->parent);
+ if (dev->busy != 0 && dev->state != DS_BUSY &&
+ dev->state != DS_ATTACHING)
+ panic("device_unbusy: called for non-busy device %s",
+ device_get_nameunit(dev));
+ dev->busy--;
+ if (dev->busy == 0) {
+ if (dev->parent)
+ device_unbusy(dev->parent);
+ if (dev->state == DS_BUSY)
+ dev->state = DS_ATTACHED;
+ }
}
/**
@@ -3000,7 +3004,10 @@ device_attach(device_t dev)
attachentropy = (uint16_t)(get_cyclecount() - attachtime);
random_harvest_direct(&attachentropy, sizeof(attachentropy), RANDOM_ATTACH);
device_sysctl_update(dev);
- dev->state = DS_ATTACHED;
+ if (dev->busy)
+ dev->state = DS_BUSY;
+ else
+ dev->state = DS_ATTACHED;
dev->flags &= ~DF_DONENOMATCH;
EVENTHANDLER_DIRECT_INVOKE(device_attach, dev);
devadded(dev);
@@ -3031,7 +3038,7 @@ device_detach(device_t dev)
GIANT_REQUIRED;
PDEBUG(("%s", DEVICENAME(dev)));
- if (dev->busy > 0)
+ if (dev->state == DS_BUSY)
return (EBUSY);
if (dev->state == DS_ATTACHING) {
device_printf(dev, "device in attaching state! Deferring detach.\n");
@@ -3083,7 +3090,7 @@ int
device_quiesce(device_t dev)
{
PDEBUG(("%s", DEVICENAME(dev)));
- if (dev->busy > 0)
+ if (dev->state == DS_BUSY)
return (EBUSY);
if (dev->state != DS_ATTACHED)
return (0);
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index 4a1afa864c2f..0942b7246ae4 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -58,6 +58,7 @@ typedef enum device_state {
DS_ALIVE = 20, /**< @brief probe succeeded */
DS_ATTACHING = 25, /**< @brief currently attaching */
DS_ATTACHED = 30, /**< @brief attach method called */
+ DS_BUSY = 40 /**< @brief device is open */
} device_state_t;
/**