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    SubjectRe: [PATCH -v3 1/7] kexec jump: clean up #ifdef and comments
    Andrew Morton <> writes:

    > On Tue, 12 Aug 2008 11:14:21 +0800 Huang Ying <> wrote:
    >> xchg(&kexec_lock, 0);
    > kernel/kexec.c: In function 'kernel_kexec':
    > kernel/kexec.c:1501: warning: value computed is not used

    A good question is why we are warned.

    > Is there any reason why we cannot use the more conventional
    > test_and_set_bit() etc, rather than this peculiarity?
    > Or perhaps spin_trylock?

    Totally odd.

    Let me stop and take a look and see what has been changed. The original
    code used a xchg based read copy update scheme, which was extremely
    compatible with a lot of goals. The primary one being no blocking paths
    in a successful kexec, and minimal dependence on library functions.

    We need that minimal dependence to handle the kexec on panic case.

    That doesn't rule out something like test_and_set_bit.


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