Messages in this thread |  | | | Date | Wed, 28 Feb 2007 22:23:41 -0800 (PST) | | Subject | Re: Thread flags modified without set_thread_flag() (non atomically) | | From | David Miller <> |
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From: Andrew Morton <akpm@linux-foundation.org> Date: Wed, 28 Feb 2007 22:03:49 -0800
> On Mon, 26 Feb 2007 12:10:37 -0800 Mathieu Desnoyers <compudj@google.com> wrote: > > > Other examples : > > > > sparc64/kernel/ptrace.c: if > > ((task_thread_info(child)->flags & _TIF_32BIT) != 0) { > > sparc64/kernel/process.c: t->flags ^= (_TIF_ABI_PENDING | > > _TIF_32BIT); > > sparc64/kernel/process.c: t->flags &= ~_TIF_PERFCTR; > > > > sparc/kernel/process.c: current_thread_info()->flags &= > > ~_TIF_USEDFPU; > > sparc/kernel/process.c: current_thread_info()->flags &= > > ~_TIF_USEDFPU; > > sparc/kernel/process.c: current_thread_info()->flags &= > > ~_TIF_USEDFPU; > > sparc/kernel/process.c: current_thread_info()->flags &= > > ~(_TIF_USEDFPU); > > sparc/kernel/traps.c: current_thread_info()->flags |= _TIF_USEDFPU; > > sparc/kernel/traps.c: task_thread_info(fpt)->flags &= ~_TIF_USEDFPU; > > That all looks rather deliberate. > > > powerpc/kernel/process.c: t->flags ^= (_TIF_ABI_PENDING | > > _TIF_32BIT); > > > > ia64/kernel/mca.c: ti->flags = _TIF_MCA_INIT; > > > > avr32/kernel/ptrace.c: ti->flags |= _TIF_BREAKPOINT; > > No, I don't immediately see anything in the flush_old_exec() code path > which tells us that nobody else can look up this thread_info (or be holding > a ref to it) in this context.
Provide the counter example, what other threads of control can modify relevant flags while a thread is exec()'ing? It's essentially frozen outside of these code paths, otherwise we wouldn't be able to make all of these modifications to the task state.
I think these cases are very safe. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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