Re: [PATCH] Linux Kernel Markers

Alan Cox
2006-09-20T10:08:32Z

Ar Mer, 2006-09-20 am 11:39 +0200, ysgrifennodd Helge Hafting:
> Yes, 5 bytes is not an atomic write except on 64-bit. So a race is possible.

Untrue as well. Pentium and later have CMPXCHG8.

> How about this workaround:
> 1. Overwrite the start of the function with a hlt, which is atomic.
> 2. Write that 5-byte jump after the hlt.
> 3. Overwrite the hlt with nop so things will work
> 4. interrupt any cpus that got stuck on the hlt - or just wait for the
> timer.

CPU errata time again. You have to synchronize.

Alan