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Commit:a8a217c221("locking/core: Remove {read,spin,write}_can_lock()") removed the definition of raw_spin_can_lock(), causing the GENERIC_LOCKBREAK spin_lock() routines to poll the ->break_lock field when waiting on a lock. This has been reported to cause a deadlock during boot on s390, because the ->break_lock field is also set by the waiters, and can potentially remain set indefinitely if no other CPUs come in to take the lock after it has been released. This patch removes the explicit spinning on ->break_lock from the waiters, instead relying on the outer trylock() operation to determine when the lock is available. Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:a8a217c221("locking/core: Remove {read,spin,write}_can_lock()") Link: http://lkml.kernel.org/r/1511894539-7988-2-git-send-email-will.deacon@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.