3cfd6625a6
In the x86 implementation of switch_mm_irqs_off(), we do not use the "prev" argument passed in by the caller, we use exclusively use "real_prev", which is cpu_tlbstate.loaded_mm. This is not obvious at the first sight. Furthermore, a comment describes a condition that happens when called with prev == next, but this should not affect the function in any way since prev is unused. Apparently, the comment is intended to clarify why we don't rely on prev == next to decide whether we need to update CR3, but again, it is not obvious. The comment also references the fact that leave_mm() calls with prev == NULL and tsk == NULL, but this also shouldn't matter because prev is unused and tsk is only used in one function which has a NULL check. Clarify things by renaming (prev -> unused) and (real_prev -> prev), also move and rewrite the comment as an explanation for why we don't rely on "prev" supplied by the caller in x86 code and use our own. Hopefully this makes reading the code easier. Link: https://lkml.kernel.org/r/20240126080644.1714297-2-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.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.