Re: How is Code in do_sys_settimeofday() safe in case of SMP andNest Kernel Path?
From: Christoph Lameter
Date: Fri Sep 29 2006 - 12:06:34 EST
On Fri, 29 Sep 2006, Dong Feng wrote:
> For my understanding, an assignment between structs should be a
> bit-wise copy. Such operation is not atomic, so it can not be supposed
Byte or Machine word yes.
> SMP-safe. And the subsequent test-and-assign operation on firsttime is
> not atomic, either.
No its not atomic on its own. Correct.
> If the comments mean the subsequent code is SMP-safe and can prevent
> nest-kernel-path, how does it achieves that?
It relies on locking outside of do_sys_settimeofday(). Seems that this
indicates locking is to be performed by the arch before calling
do_sys_settimeofday. Looks suspicious to me. Check that this function is
always called with the same lock.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/