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c2a2f505e0
Given the existing code in iwl_dbg_tlv_update_drams(), the following can happen and cause firmware asserts, and even the device to become unusable: * We set the magic so the firmware will use the data; * we try to fill multiple allocation IDs, with at least one successful, but - crucially - one failing and thus not touching the data; * we don't clear the data since there was one success. This doesn't seem like much of a problem just yet, however, what happens now is that the allocation ID(s) that failed are not initialized. There are two additional things to know: * we never free these allocations across FW restart or interface down/up etc., in fact we never free them until the driver is unbound from the device (e.g. unloaded) * the firmware uses the DRAM info structure for real debug data when it has used it completely Given that, and the fact that we never initialize the data on restart, we can be unlucky and end up with an allocation that looks for the most part valid (valid ID, valid number of buffers, etc.) but has bad sizes - causing the firmware to throw an assert we can never recover from. Fixing the code to have the entire buffers cleared (which we should do so old debug data isn't sticking around) is a bit more complex, so as a first step make the actual code that fills the information more robust by clearing the structure first, and filling the magic values only if it actually succeeded for one, rather than doing it the other way around. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Gregory Greenman <gregory.greenman@intel.com> Link: https://lore.kernel.org/r/20230613155501.87cf5528f4bc.I26ac907a4162297808b33467fc7f5d8177474a34@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> |
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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.