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authorEric W. Biederman <ebiederm@xmission.com>2005-07-29 14:03:29 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-07-29 15:01:13 -0700
commit3d483f47579461a4715db33c68ef8752e5a97a2d (patch)
tree6a4c9022074426d3551ff1b47c95f2bfe3f41828 /drivers
parent94d2ac66c12397e2ca7988dbf59f24a966d275cb (diff)
[PATCH] Fix sync_tsc hang
sync_tsc was using smp_call_function to ask the boot processor to report it's tsc value. smp_call_function performs an IPI_send_allbutself which is a broadcast ipi. There is a window during processor startup during which the target cpu has started and before it has initialized it's interrupt vectors so it can properly process an interrupt. Receveing an interrupt during that window will triple fault the cpu and do other nasty things. Why cli does not protect us from that is beyond me. The simple fix is to match ia64 and provide a smp_call_function_single. Which avoids the broadcast and is more efficient. This certainly fixes the problem of getting stuck on boot which was very easy to trigger on my SMP Hyperthreaded Xeon, and I think it fixes it for the right reasons. Minor changes by AK Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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