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Re: [Xen-devel] rwlock and per-cpu rwlock recursive?


On 02/28/2018 11:18 AM, Jan Beulich wrote:
On 28.02.18 at 11:28, <julien.grall@xxxxxxx> wrote:
Looking at the implementation, I see recursion handling for
mm_write_lock but not for mm_read_lock. Can you confirm that only the
write lock can be taken recursively?

If by "write lock" you mean an arbitrary one, then the answer of
course is no. The mm write lock machinery adds recursiveness
around percpu_write_lock(). See e.g. _mm_write_lock().

By "write lock", I meant mm_write_lock(). Thank you for the confirmation, so mm_read_lock() is not recursive.


Julien Grall

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