Re: [PATCH -mm] PM: Prevent frozen user mode helpers from failingthe freezing of tasks (rev. 2)

[Benjamin Herrenschmidt]

> Actually, spinlock_t is not suitable. Because spin_unlcok() does NOT imply
> mb(). The subsequent wait_event_timeout()->atomic_read() may leak into the
> critical section.
> 
> We can use set_mb(), if we don't want to play with smp_mb() by hand :)

spin_unlock implies a smp_wmb() but yeah, not a full mb(), though having
a read leak into a critical section is generally not an issue.

Ben.


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