On 4/15/20 10:48 AM, Sowjanya Komatineni wrote:
On 4/15/20 10:47 AM, Sowjanya Komatineni wrote:
On 4/15/20 10:21 AM, Sowjanya Komatineni wrote:
On 4/15/20 9:54 AM, Sowjanya Komatineni wrote:
On 4/15/20 7:22 AM, Dmitry Osipenko wrote:
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15.04.2020 05:57, Sowjanya Komatineni пишет:
+static int tegra_csi_remove(struct platform_device *pdev)
+{
+ struct tegra_csi *csi = platform_get_drvdata(pdev);
+ int err;
+
+ err = host1x_client_unregister(&csi->client);
+ if (err < 0) {
+ dev_err(csi->dev,
+ "failed to unregister host1x client: %d\n",
err);
+ return err;
+ }
+
+ pm_runtime_disable(csi->dev);
+ kfree(csi);
IIRC, the driver removal is invoked on the unbinding. Hence, I'm not
sure how moving away from the resource-managed API helps here.
Could you
please explain in a more details?
Have you tried to test this driver under KASAN? I suspect that you
just
masked the problem, instead of fixing it.
Using devm_kzalloc for vi/csi structures based on prior feedback
request to switch to use kzalloc all over this driver.
Hi Hans,
video devices lifetime is till video device nodes are released. So,
v4l2 device release callback does the release of tegra channel
allocation which hold video device.
Below are the 3 possible cases of unbind/unload,
1. during tegra-video module unload, if v4l2 device refcnt is not 0
which is the case when any of video device node handle is kept
opened then unloading module will not happen and module refcnt is
also non-zero and unloading tegra-video module reports module in use.
v4l2 device is associated with host1x device where during
v4l2_device_register get_device causes refcnt of tegra video host1x
device to increase and prevents allowing module unload/load till v4l2
device release happens.
2. during tegra-video driver unbind, tegra-video driver removal
will do vi/csi clients exit ops which unregisters video device
allocated memory during release callback of v4l2 device. vi/csi
structure allocation remains same as vi/csi driver removal will not
happen in this case.
3. during direct host1x client drivers vi/csi unbind, both
host1x_clients vi/csi gets unregistered, deletes host1x logical
device which executes tegra-video driver removal() -> vi/csi exit()
before vi/csi memory gets freed in vi/csi driver remove().
So, any active streaming will stop and video devices are
unregistered during direct client driver unbind prior to freeing
vi/csi memory.
Also vi/csi driver remove does explicit free vi/csi as its
allocated with kzalloc. So not sure how using kzalloc is different
to devm_kzalloc for vi/csi structure in terms of when vi/csi memory
gets freed?
Except for channel allocation which holds video device and as video
device life time is beyond tegra-video module unbind->vi exit(),
looks like we can use devm_kzalloc for vi/csi.
Can you please comment if you still think we need to use kzalloc
rather than devm_kzalloc for vi/csi structure allocation?
Thanks
Sowjanya
One more case is when video device node is kept opened with v4l2-ctl
sleep (rather than streaming), where it will keep device node open
for specified time and if direct vi client driver unbind happens
then vi driver remove() will free vi memory before v4l2 device
release happens.
But I don't see any crash or errors with this case.
In the above case, channels allocated memory release may not happen in
this case as list head pointer will be gone when vi memory is freed
during direct client unbind and by the time v4l2 device release callback
gets executed vi channels list head is gone.
Also, freeing vi structure memory can't be done in v4l2 device release
callback either.
Also if we allow direct client driver unbind, then vi structure
memory lifetime should also be till v4l2 device release happens.
But we can free vi in v4l2 device release callback as in case when
device node is not kept opened, video device release happens
immediate and we cant free vi that early.
typo fix:
But we can't free vi structure memory allocation in v4l2 device
release callback as in case when device node is not kept opened,
device release happens immediate and we can't free vi structure
memory that early.
Hans/Thierry, Can you please comment on this case?
Thanks
Sowjanya
Also, Can you please help explain on cases where we do/need direct
host1x clients vi/csi drivers unbind?
