On Thu, Dec 06, 2012 at 10:09:55PM +0000, Al Viro wrote: > What we need to guarantee is > * restarts do not happen on signals caught in interrupts or exceptions > * restarts do not happen on signals caught in sigreturn() > * restart should happen only once, even if we get through do_signal() many > times. BTW, signal caught in sigreturn is *not* something requiring a narrow race. It's perfectly normal to have some signals blocked for the duration of signal handler - the signal itself is blocked by default unless you have set SA_NODEFER in sa_flags and there's sa_mask allowing to block an arbitrary set of signals. Upon return from signal handler we undo that and if any of the temporary blocked signals has arrived while we'd been in the handler (e.g. had been raised by the handler itself), it will be caught as soon as we unblock it, i.e. in sigreturn. Unfortunately, the testcases are somewhat architecture-dependent. See, for example, arm one in commit 653d48b22166db2d8b1515ebe6f9f0f7c95dfc86; there might be a way to arrange for asm-free equivalent if one played with -O0, but it's probably not worth the trouble. That one deals with sigreturn from signal caught in interrupt; sigreturn from signal caught in syscall is a bit trickier. TBH, I don't understand your syscall calling conventions well enough to cook one up; your restart logics looks really strange. You leave ->DX[0].U0 modified - fair enough, it doesn't seem to be used by syscall entry path - *and* you revert ->DX[0].U1 to the state you used to have on entry. The thing is, I don't see any place that would have changed it in between; why do you need that regs->REG_SYSCALL = orig_syscall; in there at all? BTW, could you (and other folks submitting ports) document the ABI? See e.g. Documentation/frv/kernel-ABI.txt for fairly decent example... -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
