Messages in this thread | | | Date | Fri, 10 Apr 2015 10:22:45 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] exit: Use read lock for do_notify_parent() instead of write lock |
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* Peter Zijlstra <peterz@infradead.org> wrote:
> On Thu, Apr 09, 2015 at 08:59:08PM +0300, Kirill Tkhai wrote: > > I've not really read your email yet, however: > > > Also, in the future we may think about new rwlock primitive, which atomically > > drops write lock and acquires read lock. Something like this for example: > > > > include/asm-generic/qrwlock.h: > > static inline void queue_reduce_locked_write_to_read(struct qrwlock *lock) > > { > > smp_mb__before_atomic(); > > atomic_add(_QR_BIAS - _QW_LOCKED, &lock->cnts); > > } > > we actually have that for the rwsems: downgrade_write(). So the > consistent naming would be: queue_downgrade_write().
and 'downgrade_write_lock()' on the rwlock side.
Thanks,
Ingo
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