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Thomas Gleixner authored
Commit ea431643 ("x86/mce: Fix CMCI preemption bugs") breaks RT by the completely unrelated conversion of the cmci_discover_lock to a regular (non raw) spinlock. This lock was annotated in commit 59d958d2 ("locking, x86: mce: Annotate cmci_discover_lock as raw") with a proper explanation why. The argument for converting the lock back to a regular spinlock was: - it does percpu ops without disabling preemption. Preemption is not disabled due to the mistaken use of a raw spinlock. Which is complete nonsense. The raw_spinlock is disabling preemption in the same way as a regular spinlock. In mainline spinlock maps to raw_spinlock, in RT spinlock becomes a "sleeping" lock. raw_spinlock has on RT exactly the same semantics as in mainline. And because this lock is taken in non preemptible context it must be raw on RT. Undo the locking brainfart. Reported-by:
Clark Williams <williams@redhat.com> Reported-by:
Steven Rostedt <rostedt@goodmis.org> Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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