Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
On Tue, 2011-05-24 at 21:03 -0500, Jonathan Nieder wrote: [...] Thanks again. This and related problems should be fixed by - 8a317a87 ([media] cx88: protect per-device driver list with device lock) - 1fe70e96 ([media] cx88: fix locking of sub-driver operations) - 1d6213ab ([media] cx88: hold device lock during sub-driver initialization) - 344d6c6b ([media] cx88: protect cx8802_devlist with a mutex) - 579b2b45 ([media] cx88: gracefully reject attempts to use unregistered cx88-blackbird driver) - f4bd4be8 ([media] cx88: don't use atomic_t for core-mpeg_users) which are as of yesterday part of Linus's master branch fwiw. Now also in 2.6.39.1 and queued for 2.6.39-2, thanks. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse. signature.asc Description: This is a digitally signed message part
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
tags 619827 = upstream fixed-upstream quit Hi, Ben Hutchings wrote: On Sun, 2011-03-27 at 17:06 +0200, Huber Andreas wrote: Processes that try to open a cx88-blackbird driven MPEG device will hang up. [...] Could you test whether this patch fixes the problem? Thanks again. This and related problems should be fixed by - 8a317a87 ([media] cx88: protect per-device driver list with device lock) - 1fe70e96 ([media] cx88: fix locking of sub-driver operations) - 1d6213ab ([media] cx88: hold device lock during sub-driver initialization) - 344d6c6b ([media] cx88: protect cx8802_devlist with a mutex) - 579b2b45 ([media] cx88: gracefully reject attempts to use unregistered cx88-blackbird driver) - f4bd4be8 ([media] cx88: don't use atomic_t for core-mpeg_users) which are as of yesterday part of Linus's master branch fwiw. -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20110525020350.GA8870@elie
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
Jonathan has provided a new patch set. (RFC in progress.)
And while testing it today an unrelated issue occurred which needs
to be resolved ...
The driver's active_ref count may become negative which leads to unpredictable
behavior. (MPEG video device inaccessible, etc ...)
Here's a possible fix ...
diff -Nur a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c
--- a/drivers/media/video/cx88/cx88-mpeg.c 2011-04-02 14:34:21.456569849 +0200
+++ b/drivers/media/video/cx88/cx88-mpeg.c 2011-04-02 14:32:55.467038000 +0200
@@ -642,12 +642,16 @@
{
struct cx88_core *core = drv-core;
+ mpeg_dbg(1,"%s active driver references before release attempt: %d\n",core-name,core-active_ref);
+
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));
}
+
+ if(core-active_ref0) core-active_ref=0; // prevent us from getting negative ref counts!
return 0;
}
Tests done on amd64 hardware with 2 Hauppauge HVR1300 TV cards:
Both were independently able to tune channels and stream encoded video through
their MPEG encoder devices.
Andi.
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Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
On Sat, 2011-04-02 at 16:28 +0200, Andreas Huber wrote: Jonathan has provided a new patch set. (RFC in progress.) And while testing it today an unrelated issue occurred which needs to be resolved ... [...] I'm not going to spend more time looking at this in detail. Please let us know when a complete fix has been accepted upstream. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse. signature.asc Description: This is a digitally signed message part
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
On 02.04.2011 17:18, Ben Hutchings wrote:
[...]
I'm not going to spend more time looking at this in detail. Please let
us know when a complete fix has been accepted upstream.
Ben.
Just for clarification, what I think is going wrong in cx88-mpeg.c,
it's very simple, see the comments ...
static int cx8802_request_release(struct cx8802_driver *drv)
{
struct cx88_core *core = drv-core;
if (drv-advise_release --core-active_ref == 0) // REF COUNT MAY
BECOME NEGATIVE !!
{
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));
}
if(core-active_ref0) core-active_ref=0; // THIS IS A POSSIBLE FIX
!
return 0;
}
please review this simple fix!
regards
Andi
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Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
On Sat, Apr 02, 2011 at 08:01:15PM +0200, Andreas Huber wrote: please review this simple fix! Please let us know when a complete fix has been accepted upstream. Groeten Geert Stappers -- And is there a policy on top-posting vs. bottom-posting? Yes. signature.asc Description: Digital signature
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
Continuing Ben's work, I fixed all remaining issues. Patch was uploaded to https://bugzilla.kernel.org/show_bug.cgi?id=31962 Everything works fine for me now. regards Andi -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/4d957020.1040...@gmx.at
Re: Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
Continuing Ben's work, I fixed all remaining issues. Patch was uploaded to https://bugzilla.kernel.org/show_bug.cgi?id=31962 Everything works fine for me now. regards Andi -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/loom.20110401t082954...@post.gmane.org
Re: Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
Ben Hutchings ben at decadent.org.uk writes: 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. Hi Ben, this patch fixes the deadlock during opening of the MPEG device, thanks. But I did some testing and ran into another deadlock while unloading the (patched) driver ... rmmod cx88_blackbird ... cx88/2: unregistering cx8802 driver, type: blackbird access: shared cx88[0]/2: subsystem: 0070:9601, board: Hauppauge WinTV-HVR1300 DVB-T/Hybrid MPEG Encoder [card=56] cx88[1]/2: subsystem: 0070:9601, board: Hauppauge WinTV-HVR1300 DVB-T/Hybrid MPEG Encoder [card=56] INFO: task rmmod:11233 blocked for more than 120 seconds. ... rmmod D 88005e9086c0 0 11233 5297 0x ... Call Trace: [8131fae5] ? __mutex_lock_common.clone.5+0x12a/0x195 [810eb3d9] ? kfree+0xc1/0xda [8131f9a2] ? mutex_lock+0x1a/0x33 [a0b3a809] ? cx8802_blackbird_remove+0x27/0x3d [cx88_blackbird] [a08671f2] ? cx8802_unregister_driver+0xf1/0x1bd [cx8802] [810730a9] ? sys_delete_module+0x1df/0x251 [81009912] ? system_call_fastpath+0x16/0x1b ... And there seems to be a new problem: I have 2 identical WinTV-HVR1300 Cards ... [6.876614] cx88[0]/0: registered device video0 [v4l2] [6.889815] cx88[1]/0: registered device video1 [v4l2] [ 10.161998] cx88[0]/2: registered device video2 [mpeg] [ 13.286062] cx88[1]/2: registered device video3 [mpeg] Here's what I experienced so far: 1) booting kernel 2.6.36-trunk-amd64 from debian both cards are able to stream their mpeg encoded tv streams through the mpeg devices (in my case /dev/video2 and /dev/video3) 2) after reboot into kernel 2.6.38 /dev/video2 still works fine; tuning to different channels works! /dev/video3 is inaccessible (after doing exactly the same initialization as before) ... dd if=/dev/video3 of=/tmp/test.mpg dd: reading `/dev/video3': Input/output error 0+0 records in 0+0 records out 0 bytes (0 B) copied, 2.74267 s, 0.0 kB/s Do you think this behavior could be BKL conversion related? -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/loom.20110330t202348-...@post.gmane.org
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
Ok, thanks! On 30.03.2011 23:43, Ben Hutchings wrote: All mail regarding Debian bugs should be cc'd to the bug address (in this case, 619...@bugs.debian.org). I am not going to spend more time trying to fix this, as I don't know the media/DVB system well and do not have the hardware in question. I will forward your information to the upstream developers. Ben. -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/4d93a59b.2080...@gmx.at
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
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
Bug#619827: linux-source-2.6.38: [linux-dvb] cx88-blackbird broken (since 2.6.37)
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.
[Details]
There has been resent work on removing BKL (BigKernelLock) calls from kernel
code. (see http://kernelnewbies.org/BigKernelLock) This was not properly done
for the cx88-blackbird driver:
Source-File: drivers/media/video/cx88/cx88-blackbird.c
Function: int mpeg_open(struct file *file)
Problem: the calls to drv-request_acquire(drv); and
drv-request_release(drv); will hang because they try to lock a mutex that has
already been locked by a previouse call to mutex_lock(dev-core-lock) ...
1050 static int mpeg_open(struct file *file)
1051 {
[...]
1060 mutex_lock(dev-core-lock); // MUTEX LOCKED
1061
1062 /* Make sure we can acquire the hardware */
1063 drv = cx8802_get_driver(dev, CX88_MPEG_BLACKBIRD);
1064 if (drv) {
1065 err = drv-request_acquire(drv); // HANGS
!!!
1066 if(err != 0) {
1067 dprintk(1,%s: Unable to acquire hardware, %d\n,
__func__, err);
1068 mutex_unlock(dev-core-lock);;
1069 return err;
1070 }
1071 }
[...]
Here's the relevant kernel log extract (Linux version 2.6.38-1-amd64 (Debian
2.6.38-1)) ...
Mar 24 21:25:10 xen kernel: [ 241.472067] INFO: task v4l_id:1000 blocked for
more than 120 seconds.
Mar 24 21:25:10 xen kernel: [ 241.478845] echo 0
/proc/sys/kernel/hung_task_timeout_secs disables this message.
Mar 24 21:25:10 xen kernel: [ 241.482412] v4l_id D 88006bcb6540
0 1000 1 0x
Mar 24 21:25:10 xen kernel: [ 241.486031] 88006bcb6540 0086
8801 88006981c380
Mar 24 21:25:10 xen kernel: [ 241.489694] 00013700 88006be5bfd8
88006be5bfd8 00013700
Mar 24 21:25:10 xen kernel: [ 241.493301] 88006bcb6540 88006be5a010
88006bcb6540 00016be5a000
Mar 24 21:25:10 xen kernel: [ 241.496766] Call Trace:
Mar 24 21:25:10 xen kernel: [ 241.500145] [81321c4a] ?
__mutex_lock_common+0x127/0x193
Mar 24 21:25:10 xen kernel: [ 241.503630] [81321d82] ?
mutex_lock+0x1a/0x33
Mar 24 21:25:10 xen kernel: [ 241.507145] [a09dd155] ?
cx8802_request_acquire+0x66/0xc6 [cx8802]
Mar 24 21:25:10 xen kernel: [ 241.510699] [a0aab7f2] ?
mpeg_open+0x7a/0x1fc [cx88_blackbird]
Mar 24 21:25:10 xen kernel: [ 241.514279] [8123bfb6] ?
kobj_lookup+0x139/0x173
Mar 24 21:25:10 xen kernel: [ 241.517856] [a062d5fd] ?
v4l2_open+0xb3/0xdf [videodev]
regards
Andi Huber
-- System Information:
Debian Release: wheezy/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.36-trunk-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.ISO-8859-15, LC_CTYPE=en_US.ISO-8859-15 (charmap=ISO-8859-15)
Shell: /bin/sh linked to /bin/dash
Versions of packages linux-source-2.6.38 depends on:
ii binutils 2.20.1-16 The GNU assembler, linker and bina
ii bzip2 1.0.5-6high-quality block-sorting file co
Versions of packages linux-source-2.6.38 recommends:
ii gcc 4:4.4.5-1 The GNU C compiler
ii libc6-dev [libc-dev] 2.11.2-10 Embedded GNU C Library: Developmen
ii make 3.81-8 An utility for Directing compilati
Versions of packages linux-source-2.6.38 suggests:
pn kernel-packagenone (no description available)
ii libncurses5-dev [ncurses- 5.8+20110307-1 developer's libraries for ncurses
pn libqt3-mt-dev none (no description available)
-- no debconf information
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