some questions about kernel source

[loody]

Dear all:
I have some questions about kernel source code:
1. in kernel/trace, I always see "__read_mostly" at the end of
parameter is that a compiler optimization parameter?
2. what are below __releases and __acquires used for?
ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
__releases(ehci->lock)
__acquires(ehci->lock)
these 2 cmds are not in the {}, so I guess it will not compile out
machine. If so, why we add them after function prototype?


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Regards,