908b050114
When I got my clock parenting slightly wrong I ended up with a crash
that looked like this:
Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000000
...
pc : clk_hw_get_rate+0x14/0x44
...
Call trace:
clk_hw_get_rate+0x14/0x44
_freq_tbl_determine_rate+0x94/0xfc
clk_rcg2_determine_rate+0x2c/0x38
clk_core_determine_round_nolock+0x4c/0x88
clk_core_round_rate_nolock+0x6c/0xa8
clk_core_round_rate_nolock+0x9c/0xa8
clk_core_set_rate_nolock+0x70/0x180
clk_set_rate+0x3c/0x6c
of_clk_set_defaults+0x254/0x360
platform_drv_probe+0x28/0xb0
really_probe+0x120/0x2dc
driver_probe_device+0x64/0xfc
device_driver_attach+0x4c/0x6c
__driver_attach+0xac/0xc0
bus_for_each_dev+0x84/0xcc
driver_attach+0x2c/0x38
bus_add_driver+0xfc/0x1d0
driver_register+0x64/0xf8
__platform_driver_register+0x4c/0x58
msm_drm_register+0x5c/0x60
...
It turned out that clk_hw_get_parent_by_index() was returning NULL and
we weren't checking. Let's check it so that we don't crash.
Fixes: ac269395cdd8 ("clk: qcom: Convert to clk_hw based provider APIs")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Link: https://lkml.kernel.org/r/20200203103049.v4.1.I7487325fe8e701a68a07d3be8a6a4b571eca9cfa@changeid
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.