On Sun, 2011-03-27 at 17:06 +0200, Huber Andreas wrote: > Package: linux-source-2.6.38 > Version: 2.6.38-1 > Severity: important > Tags: upstream > > > [Symptom] > Processes that try to open a cx88-blackbird driven MPEG device will hang up. > > [Cause] > Nestet mutex_locks (which are not allowed) result in a deadlock.
Could you test whether this patch fixes the problem? Instructions for rebuilding the kernel package are at <http://kernel-handbook.alioth.debian.org/ch-common-tasks.html#s-common-official>. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse.
From 9b33bf237c5b0910efa7a20d3ebc45ba4f5cd2cf Mon Sep 17 00:00:00 2001
From: Ben Hutchings <b...@decadent.org.uk>
Date: Tue, 29 Mar 2011 03:25:15 +0100
Subject: [PATCH] cx88: Try to fix locking of sub-driver operations and device lists
The BKL conversion of this family of drivers seems to have gone
wrong. Opening cx88-blackbird will deadlock. Various other uses
of the sub-device and driver lists appear to be subject to race
conditions.
Add and use a mutex to protect the device list.
Note which driver functions require the device core lock, and make
the callers (many of which already need it) lock.
Compile-tested only.
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
drivers/media/video/cx88/cx88-blackbird.c | 4 +++-
drivers/media/video/cx88/cx88-dvb.c | 2 ++
drivers/media/video/cx88/cx88-mpeg.c | 25 ++++++++++++++++++-------
drivers/media/video/cx88/cx88.h | 4 ++++
4 files changed, 27 insertions(+), 8 deletions(-)
diff --git a/drivers/media/video/cx88/cx88-blackbird.c b/drivers/media/video/cx88/cx88-blackbird.c
index bca307e..201cdfc 100644
--- a/drivers/media/video/cx88/cx88-blackbird.c
+++ b/drivers/media/video/cx88/cx88-blackbird.c
@@ -1120,15 +1120,17 @@ static int mpeg_release(struct file *file)
videobuf_mmap_free(&fh->mpegq);
mutex_lock(&dev->core->lock);
+
file->private_data = NULL;
kfree(fh);
- mutex_unlock(&dev->core->lock);
/* Make sure we release the hardware */
drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD);
if (drv)
drv->request_release(drv);
+ mutex_unlock(&dev->core->lock);
+
atomic_dec(&dev->core->mpeg_users);
return 0;
diff --git a/drivers/media/video/cx88/cx88-dvb.c b/drivers/media/video/cx88/cx88-dvb.c
index 90717ee..5eccd02 100644
--- a/drivers/media/video/cx88/cx88-dvb.c
+++ b/drivers/media/video/cx88/cx88-dvb.c
@@ -132,6 +132,7 @@ static int cx88_dvb_bus_ctrl(struct dvb_frontend* fe, int acquire)
return -EINVAL;
}
+ mutex_lock(&dev->core->lock);
drv = cx8802_get_driver(dev, CX88_MPEG_DVB);
if (drv) {
if (acquire){
@@ -142,6 +143,7 @@ static int cx88_dvb_bus_ctrl(struct dvb_frontend* fe, int acquire)
dev->frontends.active_fe_id = 0;
}
}
+ mutex_unlock(&dev->core->lock);
return ret;
}
diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c
index addf954..57b08c6 100644
--- a/drivers/media/video/cx88/cx88-mpeg.c
+++ b/drivers/media/video/cx88/cx88-mpeg.c
@@ -78,6 +78,7 @@ static void flush_request_modules(struct cx8802_dev *dev)
static LIST_HEAD(cx8802_devlist);
+static DEFINE_MUTEX(cx8802_mutex);
/* ------------------------------------------------------------------ */
static int cx8802_start_dma(struct cx8802_dev *dev,
@@ -624,13 +625,11 @@ static int cx8802_request_acquire(struct cx8802_driver *drv)
if (drv->advise_acquire)
{
- mutex_lock(&drv->core->lock);
core->active_ref++;
if (core->active_type_id == CX88_BOARD_NONE) {
core->active_type_id = drv->type_id;
drv->advise_acquire(drv);
}
- mutex_unlock(&drv->core->lock);
mpeg_dbg(1,"%s() Post acquire GPIO=%x\n", __func__, cx_read(MO_GP0_IO));
}
@@ -643,14 +642,12 @@ static int cx8802_request_release(struct cx8802_driver *drv)
{
struct cx88_core *core = drv->core;
- mutex_lock(&drv->core->lock);
if (drv->advise_release && --core->active_ref == 0)
{
drv->advise_release(drv);
core->active_type_id = CX88_BOARD_NONE;
mpeg_dbg(1,"%s() Post release GPIO=%x\n", __func__, cx_read(MO_GP0_IO));
}
- mutex_unlock(&drv->core->lock);
return 0;
}
@@ -693,6 +690,8 @@ int cx8802_register_driver(struct cx8802_driver *drv)
return err;
}
+ mutex_lock(&cx8802_mutex);
+
list_for_each_entry(dev, &cx8802_devlist, devlist) {
printk(KERN_INFO
"%s/2: subsystem: %04x:%04x, board: %s [card=%d]\n",
@@ -702,8 +701,10 @@ int cx8802_register_driver(struct cx8802_driver *drv)
/* Bring up a new struct for each driver instance */
driver = kzalloc(sizeof(*drv),GFP_KERNEL);
- if (driver == NULL)
- return -ENOMEM;
+ if (driver == NULL) {
+ err = -ENOMEM;
+ goto out;
+ }
/* Snapshot of the driver registration data */
drv->core = dev->core;
@@ -727,7 +728,10 @@ int cx8802_register_driver(struct cx8802_driver *drv)
}
- return i ? 0 : -ENODEV;
+ err = i ? 0 : -ENODEV;
+out:
+ mutex_unlock(&cx8802_mutex);
+ return err;
}
int cx8802_unregister_driver(struct cx8802_driver *drv)
@@ -741,6 +745,8 @@ int cx8802_unregister_driver(struct cx8802_driver *drv)
drv->type_id == CX88_MPEG_DVB ? "dvb" : "blackbird",
drv->hw_access == CX8802_DRVCTL_SHARED ? "shared" : "exclusive");
+ mutex_lock(&cx8802_mutex);
+
list_for_each_entry(dev, &cx8802_devlist, devlist) {
printk(KERN_INFO
"%s/2: subsystem: %04x:%04x, board: %s [card=%d]\n",
@@ -748,6 +754,8 @@ int cx8802_unregister_driver(struct cx8802_driver *drv)
dev->pci->subsystem_device, dev->core->board.name,
dev->core->boardnr);
+ mutex_lock(&dev->core->lock);
+
list_for_each_entry_safe(d, dtmp, &dev->drvlist, drvlist) {
/* only unregister the correct driver type */
if (d->type_id != drv->type_id)
@@ -764,8 +772,11 @@ int cx8802_unregister_driver(struct cx8802_driver *drv)
"failed (%d)\n", dev->core->name, err);
}
+ mutex_unlock(&dev->core->lock);
}
+ mutex_unlock(&cx8802_mutex);
+
return err;
}
diff --git a/drivers/media/video/cx88/cx88.h b/drivers/media/video/cx88/cx88.h
index c9981e7..74a3bad 100644
--- a/drivers/media/video/cx88/cx88.h
+++ b/drivers/media/video/cx88/cx88.h
@@ -499,6 +499,8 @@ struct cx8802_driver {
int (*probe)(struct cx8802_driver *drv);
int (*remove)(struct cx8802_driver *drv);
+ /* Callers to the following functions must hold core->lock */
+
/* MPEG 8802 -> mini driver - Access for hardware control */
int (*advise_acquire)(struct cx8802_driver *drv);
int (*advise_release)(struct cx8802_driver *drv);
@@ -675,6 +677,8 @@ int cx88_audio_thread(void *data);
int cx8802_register_driver(struct cx8802_driver *drv);
int cx8802_unregister_driver(struct cx8802_driver *drv);
+
+/* Caller must hold core->lock */
struct cx8802_driver * cx8802_get_driver(struct cx8802_dev *dev, enum cx88_board_type btype);
/* ----------------------------------------------------------- */
--
1.7.4.1
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