This is a note to let you know that I've just added the patch titled
media: v4l2-async: Don't use dynamic static allocation
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-v4l2-async-don-t-use-dynamic-static-allocation.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 24e9a47e14f0a97ee97abc3dd86b2ef254448a17 Mon Sep 17 00:00:00 2001
From: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Date: Sat, 2 Nov 2013 06:20:16 -0300
Subject: media: v4l2-async: Don't use dynamic static allocation
From: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
commit 24e9a47e14f0a97ee97abc3dd86b2ef254448a17 upstream.
Dynamic static allocation is evil, as Kernel stack is too low, and
compilation complains about it on some archs:
drivers/media/v4l2-core/v4l2-async.c:238:1: warning: 'v4l2_async_notifier_unregister' uses dynamic stack allocation [enabled by default]
Instead, let's enforce a limit for the buffer.
In this specific case, there's a hard limit imposed by V4L2_MAX_SUBDEVS,
with is currently 128. That means that the buffer size can be up to
128x8 = 1024 bytes (on a 64bits kernel), with is too big for stack.
Worse than that, someone could increase it and cause real troubles.
So, let's use dynamically allocated data, instead.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Reviewed-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-async.c | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -189,30 +189,53 @@ void v4l2_async_notifier_unregister(stru
struct v4l2_subdev *sd, *tmp;
unsigned int notif_n_subdev = notifier->num_subdevs;
unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
- struct device *dev[n_subdev];
+ struct device **dev;
int i = 0;
if (!notifier->v4l2_dev)
return;
+ dev = kmalloc(n_subdev * sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ dev_err(notifier->v4l2_dev->dev,
+ "Failed to allocate device cache!\n");
+ }
+
mutex_lock(&list_lock);
list_del(¬ifier->list);
list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
- dev[i] = get_device(sd->dev);
+ struct device *d;
+
+ d = get_device(sd->dev);
v4l2_async_cleanup(sd);
/* If we handled USB devices, we'd have to lock the parent too */
- device_release_driver(dev[i++]);
+ device_release_driver(d);
if (notifier->unbind)
notifier->unbind(notifier, sd, sd->asd);
+
+ /*
+ * Store device at the device cache, in order to call
+ * put_device() on the final step
+ */
+ if (dev)
+ dev[i++] = d;
+ else
+ put_device(d);
}
mutex_unlock(&list_lock);
+ /*
+ * Call device_attach() to reprobe devices
+ *
+ * NOTE: If dev allocation fails, i is 0, and the whole loop won't be
+ * executed.
+ */
while (i--) {
struct device *d = dev[i];
@@ -228,6 +251,7 @@ void v4l2_async_notifier_unregister(stru
}
put_device(d);
}
+ kfree(dev);
notifier->v4l2_dev = NULL;
Patches currently in stable-queue which might be from m.chehab@xxxxxxxxxxx are
queue-3.12/media-af9015-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-dw2102-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-af9035-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-stb0899_drv-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-dibusb-common-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-cx18-struct-i2c_client-is-too-big-for-stack.patch
queue-3.12/media-tuner-xc2028-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-cimax2-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-tuners-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-v4l2-async-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-dvb-frontends-again-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-dvb-frontends-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-stv090x-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-s5h1420-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-av7110_hw-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-stv0367-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-lirc_zilog-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-cxusb-don-t-use-dynamic-static-allocation.patch
queue-3.12/media-mxl111sf-don-t-use-dynamic-static-allocation.patch
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