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    SubjectRe: [patch] increase spinlock-debug looping timeouts from 1 sec to 1 min

    * Ingo Molnar <mingo@elte.hu> wrote:

    > no. Write-locks are unfair too, and there's no guarantee that writes
    > are listened to. That's why nested read_lock() is valid, while nested
    > down_read() is invalid.
    >
    > Take a look at arch/i386/kernel/semaphore.c, __write_lock_failed()
    > just adds back the RW_LOCK_BIAS and retries in a loop. There's no
    > difference to an open-coded write_trylock loop - unless i'm missing
    > something fundamental.

    did i ever mention that i find rwlocks evil, inefficient and bug-prone,
    and that we should get rid of them? :-)

    (Most rwlock users can be converted to straight spinlocks just fine, but
    there are a couple of places that rely on read-lock nesting. The
    hardest-to-fix offenders are nested rcu_read_locks() in the netfilter
    code. I gave up converting them to saner locking, PREEMPT_RCU works it
    around in the -rt tree, by not being rwlock based.)

    Ingo
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