[PATCH] x86: Fix boot hang due to nmi watchdog init code
2.6.19 stopped booting (or booted based on build/config) on our x86_64 systems due to a bug introduced in 2.6.19. check_nmi_watchdog schedules an IPI on all cpus to busy wait on a flag, but fails to set the busywait flag if NMI functionality is disabled. This causes the secondary cpus to spin in an endless loop, causing the kernel bootup to hang. Depending upon the build, the busywait flag got overwritten (stack variable) and caused the kernel to bootup on certain builds. Following patch fixes the bug by setting the busywait flag before returning from check_nmi_watchdog. I guess using a stack variable is not good here as the calling function could potentially return while the busy wait loop is still spinning on the flag. AK: I redid the patch significantly to be cleaner Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Shai Fultheim <shai@scalex86.org> Signed-off-by: Andi Kleen <ak@suse.de>
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