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    SubjectRe: [PATCH]IPC locks breaking down with RCU
    Dipankar Sarma wrote:
    >
    > I took a quick look at the original ipc code and I don't understand
    > something - it seems to me the ipc_ids structs are protected by the semaphore
    > inside for all operations, so why do we need the spinlock in the
    > first place ? Am I missing something here ?

    The semaphore is used to protect the fields in ipc_ids structure, while
    the spinlock is used to protect IPC ids. For the current implementation,
    there is one spinlock for all IPC ids of the same type(i.e. for all
    messages queues). The patch is intend to breaks down the global
    spinlock and have a lock per IPC id.
    -
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